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MECHANICAL LAB Text - Physics and Astronomy

1. Item Number Description Extended Description 10221 814 00 Sys VLM3 3 3 635nm 2 5mW E CW VLM3 635nm 2 5mW Elliptical Beam 4 6 x 1 3 mm 9 53 mm dia 25 46x13 02x0 7 914 none 10221 534 00 Sys VLM2 3 5 635nm 4 2mW E CW VLM2 635nm 4 2mW Elliptical Beam 5 8 x 1 7mm 14 7 mm dia 42 58x17 02x06 914 none 10221 895 01 Sys VLM2 3 11 635nm 10mW E CW IVLM2 635nm 10 5mW Elliptical Beam 5 8 x 1 7mm 14 7 mm dia 105 58x1 7 02x06 914 none 1051904 Sys VLM2 3 21 635nm 21mW E CW VLM2 635nm 21mW Elliptical Beam 5 8 x 1 7mm 14 7 mm dia 21 5 8 x1 7 02x06 914 none 31 0607 000 Sys VLM3 5 4 650nm 4mW E CW VLM3 650nm 4mW CW Elliptical 4 x 1 mm beam with phono connector 9 53 mm dia 4 4x11 0 3x 1 0 990 Wees VLM3 650nm 0 9mW Elliptical Beam Internal 3 3 volt regulator for protection and 580 Sys VLM3 5 1 650nm 1mW E Rt 0222 580 01 ys nm 1ml eg stability Case at 3 3Volts Operates at 4 5 6 VDC 9 53 mm dia 0 95 1x37 0 3x 1 0 914 none 0222 764 00 Sys VLM2 6 25L 660nm 25mW E CW IVLM2 660nm 25mW Elliptical Beam 0 5 x 1 3mm Laser Case at Ground Potential 14 7 mm dia 25 0 5x1 3 17x07 914 none 10221 023 00 Sys VLM2 1 670nm 1mW Ellip VLM2 670nm 0 9mW Elliptical Beam 3 3 x 1mm 14 7 mm dia 0 95 3 3x1 0 3x 1 0 914 none 10220 970 00 Sys VLM3 1 670nm 1mW Ellip VLM3 670nm 0 9mW Elliptical Beam 4 6 x 1 3mm 9 53 mm dia 0 95 46x13 0 2x0 7 914 none l0221 202 00 Sys VLM2
2. Recon eege Settings Reset All Variables To Defaults esee Strip aere Strip Background Load Spectrum sese Strip Background Load Background teniente ence Strip Background Show Spectrum eret road eti trend Strip Background Show Background eee Strip Background Overlay Spectrum Strip Background Strip Background from Spectrum Keel E EE Spectrum Techniques UCS 30 Gw ww nws sO FqKT awas 111 1 sje E 49 eebe Eege 50 Show u ci disi ire ARM 50 Show Data Report lC HO PNN 50 Pap V Vb ST aiara 50 hus RM E EE 50 p mc aT 50 Spectrum Window SIZIng nn ute ML det o Lb E teeta uedn a 50 KE EE c 51 KE E 51 SEENEN 52 LE EE 52 veri M T 53 Spectrum Techniques Contact pM nn nnsnssnanaa 53 Spectrum Techniques UCS 30 Introduction Hardware The Universal Computer Spectrometer offers a unique solution for nuclear spectrometry using the PC platform A 4K ADC optional combined with 8K of data memory and multi channel scaling is ideally suited to scintil
3. LAB 2 Experiments in Nuclear Physics John A J Matthews Michael P Hasselbeck and Paul R Schwoebel Purpose Introduce the student to some of the basic techniques and approaches used in nuclear and particle physics Reading Assignment Reading required as per references in text of experiment Preface This laboratory is divided into two sections The first section is an introduction to gamma ray spectroscopy y ray spectroscopy is of both fundamental and applied interest The techniques introduced in y ray spectroscopy will be expanded upon and used in the second section to measure the mean life of the muon The mean life of the muon is directly related to the fundamental strength of the Weak Nuclear Force one of the four fundamental forces in nature Part 1 Gamma Ray Spectroscopy Introduction The decay of many radionuclides involves the emission of y rays Processes that leave the daughter in an excited state can lead to gamma emission Alpha emission and beta emission precede gamma decay in the natural radionuclides For example there can be a large difference between the nuclear spin of the ground states of the parent and the daughter Then the beta transition directly to the ground state of the daughter is forbidden and therefore most of the transitions leave the daughter in an excited state Decay schemes for some radionuclides are shown below Co 5 26yr 1370s 30yr 57Co p 0 31 MeV p 0 51 MeV Electron Capture
4. 10 11 10 12 EADCI Im 10 13 10 14 300 400 500 600 80 1000 1200 SUPPLY VOLTAGE V Data shown here which is given from a relation among supply voltage anode sensitivity and dark current serves as a good reference in order to determine the most suitable supply voltage or its range Figure 7 Typical Temperature Characteristics of Dark Count for R1527P TPMSBO0030EA 10 103 T Q 9 Lo 102 z 2 e o ZS 10 lt a 100 10 1 20 0 20 40 60 TEMPERATURE C PHOTOMULTIPLIER TUBES R1527 R1527P For Photon Counting Figure 8 Dimensional Outline and Basing Diagram Unit mm 28 541 5 8MIN PHOTOCATHODE 24MIN 49 0425 Wf PIN BASE JEDEC No B11 88 Figure 10 Socket E678 11A Optional 33 DY1 I K i DIRECTION OF LIGHT BOTTOM VIEW BASING DIAGRAM hd TPMSA0001EA Figure 9 D Type Socket Assembly E717 21 Optional 33 0 0 3 38 0 0 3 49 0 0 3 4 8 in S H x HOUSING INSULATOR E POTTING NCOMPOUND 8 X Hamamatsu also provides C4900 series compact high voltage power sup plies and C6270 series DP type socket assemblies which incorporate a DC
5. Swee X Trace E RBW VBW ST AS lt SA 3 lt Se lt Ki hc EN um S 8 vw k K M He i A A E i O1O O O O OI O O VC 1 1 1 1 Input Status Trigger Entry P Figure 1 Layout of the HP 3585A Spectrum Analyzer front panel 5 8 The Eight Panel Groups 1 INPUT Proper settings and connections of the INPUT group are required to obtain a trace and to prevent overloading For low frequency applications the IMPEDANCE should be set to 1 MQ the 50 Q and 75 Q inputs need to be used only when investigating frequencies of gt 10 MHz and when the source is capable of driving such an impedance The signal source must be connected to the input jack corresponding to the active IMPEDANCE setting When AUTORANGE is on the input amplifier RANGE will be adjusted to suit the input signal with REF LEV TRACK on the power level corresponding to the top of the display grid will follow any adjustments of the RANGE whether this is due to AUTORANGE or to any manual STEP KEY or numerical entry 2 ENTRY This group is the most important of the eight In particular the REFERENCE LEVEL dB DIV START FREQ STOP FREQ and or CENTER FREQUENCY FREQUENCY SPAn may be set using the STEP numerical and unit keys To change the value of any of these parameters press the corresponding key The corresponding CRT entry will then be highlighted and the value may be changed either incrementally using
6. 22 Transit Time Spread TTS K 1 2 Anode Current Stability Current Hysteresis 0 1 Voltage Hysteresis 1 0 NOTES A Averaged over any interval of 30 seconds maximum B The light source is a tungsten filament lamp operated at a distribution tem perature of 2856K Supply voltage is 150 volts between the cathode and all other electrodes connected together as anode C The value is cathode output current when a blue filter Corning CS 5 58 polished to 1 2 stock thickness is interposed between the light source and the tube under the same condition as Note B D Measured with the same light source as Note B and with the anode to cathode supply voltage and voltage distribution ratio shown in Table 1 be low E Measured with the same supply voltage and voltage distribution ratio as Note D after removal of light F Measured at the voltage producing the gain of 1x 106 G ENI is an indication of the photon limited signal to noise ratio It refers to the amount of light in watts to produce a signal to noise ratio of unity in the output of a photomultiplier tube ENI V 2q ldb G f S where q Electronic charge 1 60 X 10 19 coulomb Idb Anode dark current after 30 minute storage in amperes G Gain f Bandwidth of the system in hertz 1 hertz is used S Anode radiant sensitivity in amperes per watt at the wave length of peak response H The rise time is the time for the output pulse to rise from 10 to 90 of the pe
7. Displays a splash screen with the Application name and version number About UCS30 Tool Bar ss File Edit Mo Go allows the user to start the acquire mode of a spectrum This can also be accomplished by clicking on the green Start Icon on the display screen Optionally pressing A while pressing and holding Ctrl and Shift keys will start acquisition Spectrum Techniques UCS 30 Stop allows the user to stop the acquire mode of a spectrum This can also be accomplished by clicking on the red Stop Icon on the display Optionally pressing S while pressing and holding the Ctrl and Shift keys will stop acquisition 49 ra Erase A Erase allows the user to erase the spectrum when in stop mode This can also be accomplished by clicking on the Eraser Icon on the display screen Optionally pressing E while pressing and holding the Ctrl and Shift keys will initiate an erase request Caution If Settings Confirm Spectrum Erasure is unchecked erasure is immediate and final Show Peak Report If regions of interest ROIs have been set around peaks in a spectrum the Peak Report provides a convenient method of displaying peak information in tabular form Readout will be in energy units if the energy calibration is active Show Data Report Data Report includes all hardware setting counting parameters and spectrum data ROI data is reported by lower and upper channels set gross net
8. E 0 122 MeV E 1 17 MeV E 0 66 MeV E 0 014 MeV 57Fe stable 137Ba stable E 1 33 MeV DN stable Often the half life of the parent is very long relative to the half life of the daughter In this case gamma decay is in transient equilibrium with the decay of the parent and the y ray intensity falls off with the half life of the parent This is the reason it is customary to name the parent as the y ray source 2 1 y ray spectroscopy has a number of important uses in the applied sciences For example it can be used to identifying much of the elemental composition of an unknown sample To do this the unknown sample is irradiated with neutrons which makes the sample radio active This is so called neutron activation One can then measure the y rays and p rays and sample half life to determine the constituents and their relative concentrations This technique is used in the petroleum industry and areas of geology medicine and criminology to name a few To learn about y ray spectroscopy and standard instrumentation used in nuclear physics you will 1 Observe y ray energy spectra 2 Identify the processes taking place gt 3 Complete an energy calibration of the apparatus 4 Determine the identity of an unknown isotope 5 Determine the attenuation coefficients of y rays as a function of y ray energy II Procedure A radioactive y ray source is placed near a Nal TI scintillatio
9. Setup Temperature Compensation Setup The setup menu provides the UCS 30 with the length of time it should monitor temperature variations to calculate the temperature coefficient The interval which must be set to 5 60 minutes is how often the UCS 30 measures the temperature and cesium peak The time which must be set to 4 24 hours is how long the UCS 30 will stay in calibration mode Parameters Temperature Correction The fine high voltage factor measured in channels step and temperature coefficient measured in channels degree celsius can be entered in the parameters menu Also temperature compensation may be enabled in this dialog box by clicking the enable checkbox The parameters are automatically changed and temperature compensation is enabled after calibrating for temperature compensation 27 ine FI Selecting calibrate will initiate an acquisition sequence that attempts to determine the compensation parameters First it attempts to AutoCalibrate the system Once energy calibrated the UCS 30 will attempt to find the temperature compensation parameters by finding the cesium peak at the specified interval over the specified time Isotope Matching Temperature Calibration in Progress ED wm Since the calibration will take several hours an information dialog box is displayed which advises to wait for completion and provides an opportunity to cancel the calibration Pressing of the C
10. Smooth Data Click Smooth Data to perform a 3 point averaging of the data currently being displayed The function uses the following algorithm to average data in each channel where n is the channel number n 1 n n1 3 Menu Bar Many advanced functions are possible via the pulldown menus This section describes each operation in the sequence they appear Black letters indicate the function is operational gray indicates not operational highlighted indicates the function to be activated File Edit Mode Display Settings Strip Background View Help File File Open Ctrl O Save Ctrl S Load Setup Save Setup Load Isotope Library Save Isotope Library Print Ctrl P Print Preview Print Setup Exit Spectrum Techniques UCS 30 34 File Open File Open allows the user to open data files A new instance of the UCS 30 application in the File Mode is generated File Save The spectrum data and the associated setup and experiment data are saved to a spu file File Load Setup Used if power has been turned off to the USC30 Load Setup loads a previously saved setup file and quickly restores the analyzer to its previous operating condition High Voltage must be turned on after loading setup File Save Setup Once the UCS 30 has been setup and calibrated Save Setup stores all operating parameters as a disk file for subsequent retrieval See Load Setup description above for this procedu
11. ment 3 1 to measure the photopeak energies of an unknown gamma emitter and to identify the unknown isotope Procedure 1 Erase the Co spectrum from the MCA but do not change any of the gain calibration settings of the system Event Energy MeV Channel No Photopeak 1 33 560 Photopeak 1 17 496 Photopeak 0 662 280 Energy MeV 8147 200 300 400 500 600 Channel Number Fig 3 4 Energy Calibration Curve for Nal TI Detector 2 Obtain an unknown gamma source from the instructor Accumulate a spectrum for the unknown source for a period of time long enough to clearly identify the photopeak s of the source From the calibration curve determine the energy for each photopeak EXERCISE Use refs 7 and 8 to identify the unknown isotope 17 EXPERIMENT 3 Jp EG G ORTEC EXPERIMENT 3 3 Spectrum Analysis of Co and Cs Purpose The purpose of this experiment is to explain some of the features other than the photopeaks that are usually present in a pulse height spectrum These are the Compton edge and the backscatter peak The Compton interaction is a pure kinematic collision be tween a gamma photon and what might be termed a free electron in the Nal TI crystal By this process the incident gamma gives up only part of its energy to the electron The amount given to the recoil electron and the intensity of the light flash depends on whether the collision is head on or glancing For a head on col
12. 10 mV to 1 Volt 15 turn screwdriver ad justment better than O 296 C stability front panel test point provides a DC voltage ten 10 times the actual threshold setting Fast Veto One LEMO connector input common to all eight 8 channels accepts normal NIM level pulse 500 mV 50 ohms direct coupled must precede the negative edge of input pulse by 5 nSEC 5 nSEC minimum input width Bin Gate Rear panel slide switch enables or disables slow bin gate in accordance with TID 20893 GENERAL PERFORMANCE Continuous Repetition Rate OUTPUT CHARACTERISTIC General Three LEMO connector outputs per channel One negative bridged pair and one comple mentary output The bridged outputs deliver 32mA into a single 50 ohm load 1 6 volts or l mA 800mV when both outputs 50 ohm terminated The complement is quiescently l6mA BO0mV and goes to OmA during output The output rise and fall times are less than 1 5 nSEC from 1096 to 9096 levels Width Control One controi per channel 15 turn screwdriver adjustment outputs continuously variable from 6 nSEC to 150 nSEC non updating x 296 C stability Summed Output One LEMO connector output common to all eight B channels 1 mA output pulse 50 mV into 50 ohms for each channel fired Output duration is equal to the out put width setting of the respective channel Output rise and fall times less than 2 5 nSEC into 50 ohms Up to 16 channe
13. Amplifier Coarse CAT aere Eeer 19 Amplifier Fme Crain mm 19 ADC Conversion E 20 Lower and Upper Level Discriminators iie rout eon d viride eie Pusat 20 Voltage Polarity ua uuu 21 Ipput Pol rity E 21 Peake Time EN 22 Eeer 23 Pr s t TIME E 23 Preset Integral ua sosirii siis eiei ea AARE EEA E A 24 G Slop and E 24 Regions OF eege 24 latns M dee 25 Energy CAHDFR800B ER 25 Temperature e EE 27 IE reise Site Me T 28 Strip sr e e MT m 31 Load Sp Ctr m u 32 BR DE 32 Show E EE 32 Show Background 32 Overlay SC CU rica E 33 Strip Background from EE 33 IR 34 Eeer 34 lu 34 Spectrum Techniques UCS 30 La ai Fil BE File Save EN Pile Load Library EEN File Save Ee EE ah E Pile Print Preview MN Fil PrInt SetD irssi chduce das ecasachacesasdaaoeese tena anaE r ES ial EE ERSE File E jo ei ge Edit ISO I otc bia e HP steele Display Peak Report ee ER Re Display Calibratt it iioc Eege Display TECH Display Iso M at h al aaa Qaqaqa qa eegene Display Feel Zeene SeN EE Settings E Settings Energy Calibrate reese ege Settings PLE SEL EE Settings Amp FIV ADC u a yas sansapa E a e Settings EE Settings Confirm Spectrum Erasutre
14. Mono 0220 56 00 Sys Indust LG 85Deg 635nm 9mW Industrial Laser Diode Module Line Generator 635nm 9 2mW 85 Degree Fan Angle 19 22 mmdiax142mm 92 1 e 304 none mrad x Phono 31 0268 000 Sys LabLaser 85 Deg 635nm 6mW LabLaser 635nm 6mW Line Generator 85 Degree Fan Angle CW Phono Plug Connector 19 22 mm dia x142 mm 6 1 85deg 990 Stereo 0220 971 00 Sys LG2 3 85Deg 635nm 2mW VLM2 Line Generator 635nm 2 5mW 85 Degree Fan Angle 9 5 mm 25 1 den 914 none 0220 86 00 Sys LG2 85deg 670nm 2mW VLM2 Line Generator 670nm 2 5mW 85 Degree Fan Angle 9 5 mm 25 1 Ee 914 none 0223 062 00 Sys LG3 3 85deg 635nm 3mW EPX VLM3 Line Generator 635nm 3mW 85 Degree Fan Angle Epoxy Wire Strain Relief 9 5 mm 3 1 past 914 none mrad X Phono 31 0615 000 Sys LG3 5 85deg 650nm 3 7mW VLM3 Line Generator 650nm 3 7mW 85 Degree Fan Angle with Phono Connector 9 5 mm 3 1 85deg 990 Mono 0221 153 00 Sys LG3 85D 670nm 3 8mW 85deg VLM3 Line Generator 670nm 3 8mW 85 Degree Fan Angle 9 5 mm 38 1 Hos 914 none 0222 337 00 Sys LG3 X Line 635nm 2mW Cross VLM3 Line Generator Diffractive Cross Hair 635nm 2mW 25deg Fan Angle 9 5 mm 2 1 25deg 914 none ond Sys LG2 X Line 635nm 1mW Adj VLM2 Line Generator Diffractive Cross Hair 635nm 1mW Adjustable Focus Line Width 25 Ar wen di 098 i 25deg x Sp Se Degree Fan Angle Adjustable lizzo ood oU Sys LG2 X Line 635nm 2mW Adj VLM2 Line Generator Diffractive Cross Hair 635nm 2mW Adjustable Focus Line Width 25 11
15. The scattered light may be viewed from the side as shown in Fig 2 A lens L is used to collect the scattered light and focus it onto the detector PD As before the detector signal is sent to the spectrum analyzer The signal frequency of interest may be discerned by blocking either of the interfering beams it should disappear Position the wheel transversely to maximize the scattering frequency i e so that the scattering comes from the foremost point on the wheel Adjust the spectrum analyzer to fully resolve the signal frequency and measure its value Also measure the diameter of the wheel and estimate its rotation rate observing the detector signal on an oscilloscope though it may be quite noisy it should be periodic over one rotation 5 4 PD Figure 2 Experimental setup for the transverse speed measurements Most labeled parts are as in Fig 1 except that L is a collecting lens optional M is a flat mirror and XYZ is a PC to which the spectra can be transferred Report the measured frequency and its bandwidth Calculate and L and the rotation rate How does this compare with the oscilloscope estimate Which would you expect to be more accurate and why What are the major sources of error in this experiment and in particular what is the effect of the bandwidth of the measured scattering frequency Velocity profile of flowing water This is probably the most difficult part of the experiment It is d
16. This mode requires the use of an external amplifier The signal must connect to the MCS INPUT BNC connector The Mossbauer External mode has variable dwell time ranging from 100 uSec to 6 Sec A Preset number of passes can be set to the desired number or left at zero 0 for infinite passes The following is the Mossbauer spectrum of a Co 57 source with an enriched Fe 57 absorber showing nuclear Zeeman splitting Spectrum Techniques UCS 30 15 Operation instrument and is used only to view and Live Mode manipulate files that have been saved to disk JA Spectrum Techniques UCS30 Live Mode File Mode The software starts up in the Live Mode This A Spectrum Techniques UCS30 File Mode icsdemo spe mode uses the USB to communicate with the instrument File Mode is accessible from the live mode by going to the File Menu and clicking on Open If you access the File Menu and click on Select the file you want to view Some Open a new window appears which looks like functions which have no use when viewing the current window except that the title bar files are disabled in the Menus and the shows File Mode instead of Live Mode Toolbar File mode does not communicate with the Amp HV ADC Click the Amp HV ADC Button on the toolbar H ge l Or use the settings menu and click on Amp HV ADC Spectrum Techniques UCS 30 16 ew RR C The Amp HV ADC dialog box will appear Amp H
17. cos ast A cos o t A cos w t 2 2 Typically in particular if we work with light the frequencies o cannot be resolved directly and the detection system averages the terms 1 2 and 4 in Eq 2 2 The time dependence of the signal the 3 term in 2 2 is then characterized by a frequency DVpeat c This modulation is also referred to as a beat frequency or a beat note after the analogous acoustic phenomenon When two nearly identical tones are played together the result is a waa waa waa variation of the loudness with a periodicity equal to the inverse of the frequency difference of the two tones So the heterodyne technique eliminates problem 1 above as long as the Doppler shift is not too large But what of problem 2 The stability of a small He Ne laser over a time span of a few seconds is certainly no better than a several MHz Thus you should not be able to measure speeds lt 2 m s 10 km hr right Wrong as can be seen by comparing the coherence time of such a laser tens of ns the time delay between the signal and reference beams for the experimental arrangements used here lt 1 ns and the Schawlow Townes linewidth of a laser Hertz Qualitatively what would be the limit of such a measurement Note It is worth devoting a few lines to this in your report The theory of the Doppler effect is covered in most basic physics texts and will not be discussed here The ar
18. take sufficient spectra to measure u at several energies and for at least two absorber materials How do your results compare with tabulated values for u Part 2 Measurement of the Mean Life of the Muon 2 4 Introduction The muon is an elementary particle indistinguishable from the electron except that its mass is 200 times greater Muons are produced primarily from the decays of charged pions z which are themselves produced copiously in extensive air showers caused by cosmic rays Primary cosmic rays cover the spectrum from protons to intermediate mass nuclei lt iron The primary cosmic rays interact with nuclei in the atmosphere creating large numbers of charged and neutral z mesons These subsequently interact or decay Depending on the energy of the initial cosmic ray millions or billions of secondary particles can be produced This is called an extensive air shower Generally the neutral mesons z decay before interacting Depending on their energy the charged pions may interact with nuclei in the atmosphere or may decay a w v to charged muons and neutrinos To understand this behavior look up the lifetimes t and masses m of charged and neutral pions The average distance they travel before decaying depends on their energy E and is given by Distance E m c c t where c is the speed of light What are typical distances if E 10 eV or if E 10 eV If this distance is large then it is like
19. 5 670nm 4 2mW E MVP VLM2 670nm 4 2mW Elliptical Beam 4 x 1 2mm Modulation and Variable Power Contr 14 7 mm dia 42 4x12 03x08 914 ione on third lead Recommend 6VDC 0220 986 00 Sys VLM2 5 670nm 4 2mW Ellip VLM2 670nm 4 2mW Elliptical Beam 1 x 3mm 14 7 mm dia 42 3x1 0 3x1 0 914 none 10220 968 00 Sys VLM3 3 670nm 2 5mW E VLM3 670nm 2 5mW Elliptical Beam 1 x 4mm 9 53 mm dia 42 4x1 0 2x 0 7 914 none 10223 038 00 Sys VLM2 8 670nm 7 5mW SPC VLM2 670nm 7 5mW Elliptical Beam 1 x 3mm Shielded Cable 14 7 mm dia 75 34x13 03x08 305 none 10222 929 00 Sys VLM2 785nm 15mW Ellip VLM2 785nm 15mW Elliptical Beam 2 7 x 1 2mm CW 14 7 mm dia 15 27x12 04x09 914 none VLM2 785nm 40mW Adjustable Power with back panel potentiometer special foc 45x1 5 1006427 Sys VLM2 785nm 40mW ADJ Power 4 5mm X 1 5mm at 965mm distance Third wire for laser current sense with 10mV equals 14 7 mm dia 40 e Special 267 none 1ma of laser drive 965mm Item Number Description Extended Description 31 0458 000 Sys FVLM2 635nm 1mW C CW Adj VLM2 635nm 0 95mW Adjustable Focus Circular Beam 3mm Phono Plug Connector 8 14 7 mm dia xmax 51 0 95 3 04 990 Mono 0220 862 00 Sys FVLM2 670nm 1mW C Adj VLM2 670nm 0 9mW Adjustable Focus Circular Beam 3mm 8 14 7 mm dia xmax 51 0 95 3 04 914 none 0222 57 01 Sys FVLMS GSonmm 4mW C Adj OEM vine G650nm TmW Circular Beam 3 mm Adjustable Focus Mi
20. 8 The Linear Gate in Gamma Ray Spectroscopy Purpose The purpose of this experiment is to show how a linear gate can be used with an MCA in gamma ray spectroscopy The linear gate will limit the analysis of input pulse amplitudes to those that will be included within the photopeak The measurement of the mass absorption coefficient in Experiment 3 7 required the accumulation of several com plete spectra although the data of interest were included within only a fraction of the total number of channels that were used The normal time for completing Experiment 3 7 is approximately 45 min By using a linear gate the same information can be obtained in about 1 3 of the time An equivalent saving of time can also be made in Experiments 3 5 and 3 6 Source Activity Determinations Since the pro cedures are about the same as for Experiment 3 7 the student should repeat these experiments with the linear gate to see how much time will be saved See equipment list at beginning of Experiment 3 for addi tional equipment required for Experiment 3 8 Connect the system components as shown in Fig 3 7 Con nect the bipolar output of the 575A Amplifier to both the 427A Delay and the 551 Timing Single Channel Analyzer Con nect the Delay output to the linear Input of the 426 Linear Gate and connect the gate output to the analyzer input Connect the SCA output to both the 875 Counter input and the Enable input of the Linear Gate The Linear Gate
21. Beam 1 3mm 19 22 mm dia x142 mm 5 13 08 990 o 31 0227 000 Sys LabLaser 635nm 7mW C CW LabLaser 635nm 7mW Circular Beam 1 3mm CW Phono Plug Connector 19 22 mm dia x142 mm 7 13 08 990 elen baus 000 Sys LabLaser 635nm 7mW C MVP LabLaser 635nm 7mW Circular Beam 1 3mm Modulation and Variable Power Control Phono 55 mm dia x142 mm 7 13 08 990 Prono Plug Connector Stereo 31 0326 000 Sys LabLaser 635nm 10mW C CW LabLaser 635nm 10 5mW Circular Beam 1 3mm CW Phono Plug Connector 19 22 mmdiaxi42mm 10 5 13 08 990 Weien Peer Sys LabLaser 635nm 10mW C MVP LabLaser 635nm 10 5mW Circular Beam 1 3mm Modulation and Variable Power Control 19 22 mmdiaxi 2mm 105 13 08 en Phono Phono Plug Connector Stereo Item Number Description Extended Description 0221 437 00 Sys AM 2 Adj Mount VLM2 15mm Mount Laser Diode Module Adjustable for VLM2 Modules 14 8mm 37 5 x 12 5 x 48 3mm 0221 448 00 Sys AM 3 Adj Mount VLM3 9mm Mount Laser Diode Module Adjustable for VLM3 9 5mm 37 5 x 12 5 x 48 3mm ee Sys AMET Adj Mount Lab dana emt Gase Diode Module Adjustable for LabLaser or Industrial Modules 19mm 37 5 x 12 5 x R Mount Laser Diode Module LabLaser 4 axis fine adjust 2deg angle adj 3 5mm X Y 31 1605 000 Mount 4 Axis Lablaser 53 4939 adjustment universal Recommend also buy 53 1962 Adaptor maai Mount amar AD A mobic fescioss Mewt Laser pde M
22. FWHM centroid all channels and corresponding counts Amp HV ADC Spectrum Techniques UCS 30 Allows the user to select the Amp HV ADC Dialog box Presets g A gt Allows the user to select the Presets Dialog box ROI Allows the user to set an ROI Spectrum Window Sizing These buttons allow the user to set the size of the X and Y axes If a button is grayed its function is not available for use Scroll bars will appear when a spectrum is zoomed in or when it is being viewed in linear mode to provide further control Y axis Log Y loq Clicking the Y axis Log button sets the Y axis to a logarithmic scale with a maximum range of 16 million counts 50 X axis expand X axis contract Clicking the X axis expand button increases Clicking the X axis contract button decreases the span of the X axis up to the maximum set the span of the X axis by the Conversion Gain Status Bar Ready HV 7500N LT9 DIR D Volt Polarity Pos The status bar at the bottom of the window displays a context sensitive help message on the left side the high voltage live time real time the selected device high voltage and input polarities on the right side Spectrum Techniques UCS 30 51 m o nnn Specifications Hardware Physical Single instrument includes preamplifier amplifier detector high voltage 4096 channel maximum multichannel analyzer with data memory LLD and ULD Fully compati
23. Filtrol 6801 Cochran Rd Solon Ohio report FWHM Ey 7 9 at 662 KeV for Nal TI detectors 13 W R Leo Ch 4 Statistics and Error Analysis 14 F Halzen and A D Martin Quarks and Leptons an Introductory Course in Modern Particle Physics Wiley New York 1984 15 Particle Data Group Phys Rev D 54 1 1996 2 12 APPENDIX 1 Time to Amplitude Converters Bill Miller and Paul Schwoebel A Time to Amplitude Converter TAC is a device that accepts a start pulse and waits for a stop pulse Circuitry inside the TAC determines how much time has elapsed between the two pulses The TAC produces a voltage pulse with an amplitude that is proportional to the elapsed time To use the TAC 1 Check if there are any special power requirements like 6 V This can usually be found on the front panel Some units have a rear panel switch that allows for either 12 V of 6 V Make sure that your NIM bin has correct voltages available 2 Check to see what logic family the unit uses NIM logic a V looking character or TTL a representation of a positive going pulse Some units can be switched between the logics 3 Set up the TAC for the proper time scale If you set it up for a 1 us scale and give it a signal with 2 us between start and stop you will not get an output from the TAC Similarly If you select 1 us and deliver only 1 ns the TAC will provide no output 4 There can be a number of extra functions on the front panel For C
24. Gamma Emitter Relative Method Purpose In Experiments 3 1 and 3 3 procedures were given for deter mining the energy of an unknown gamma source Another EXPERIMENT 3 SOURCE m fi ESCAPE OF x ONEKXRAY S BETA ABSORBER gt x COMPTON D SCATTERING PHOTON DEE UV PHOTONS Produced from Local Excited States Following lonization Pb SHIELDING DYNODE Secondary Electron Emission k MMMM A ANODE 5 B NI A ANNIHILATION d RADIATION ANNIHILATION RADIATION REFLECTOR e Pb SHIELDING PHOTOCATHODE Pb X RAY vA PHOTOMULTIPLIER PE D x BR EMSSTRAHLUNG p x PHOTOELECTRON Emitted from Cathode Fig 3 5 Various Events in the Vicinity of a Typical Source Crystal Detector Shield Configuration unknown associated with the gamma source is the activity of the source which is usually measured in curies Ci 1 Ci 37 x 10 disintegrations s Most of the sources that are used in nuclear laboratory experiments have activities of the order of microcuries uCi The purpose of this experi ment is to outline one procedure by which the activity of a source can be determined called the relative method in using the relative method it is assumed that the unknown source has already been identified from its gamma energies For this example assume that the source has been found to be Cs Then all that is necessary is to compare the activity of the unknown sou
25. MeV gamma to the ground state In Experi ment 19 we will show that these two events are in coincidence and have an angular correlation that deviates from an iso tropic distribution by only 1696 For the purposes of this experiment we can assume that each of these gammas are isotropically distributed In other words if y goes in a par ticular direction y can go in any of the 47 steradians that it wishes There is a certain probability that it will go in the same direction as y If this occurs within the resolving time of the detector yi and y will be summed and hence a sum peak will show up in the spectrum From the definitions in Experiment 3 6 the number of counts X under the yi peak is given by gt i GfitA 11 where A is the activity of the sample and t is the time In a similar calculation the sum X for 2 is given by X eGf A 12 From Eqs 11 and 12 the number of counts in the sum peak X is given by X eefif G2At W 0 13 where W 0 is a term that accounts for the angular correla tion function For the case of Co Eq 13 is quite simple X becomes X eeG At 14 since W 0 1 0 In this experiment we will show that the sum peak for Co has an energy of 2 507 MeV and that its sum is given by Eq 14 006 5 26 y B 99 at L 2507 MeV EON D 7x Ve 1 3325 MeV 1 2 o 0 SONI Fig 3 9 The Decay Scheme of Co Procedure 1 Set up the electronics
26. Strip Background View Help Load Spectrum Load Background v Show spectrum Show Background Overlay Spectrum and Background Strip Background from Spectrum Click Show Spectrum to view spectrum Show Background Strip Background View Help Load Spectrum Load Background Show spectrum Show Background Overlay Spectrum and Background Strip Background from Spectrum Click Show Background to view background 32 Overlay Spectra Click Overlay Spectra to view the spectrum and the background at the same time A Spectrum Techniques UCS20 File Mode TEST1 spu m m F4 2 Hmm ElEj PN AVE Z EG EE HE I 255 Channel 511 Energy Gross FWHM Counts 5 et Centroid Strip Background from Spectrum Strip Background View Hep Load Spectrum Load Background Show spectrum Show Background Overlay Spectrum and Background Strip Background from Spectrum Click Strip Background from Spectrum to subtract the two spectra where the background is corrected for the difference in the data collection time to give a correct proportion As an example if the background count time is 10 minutes and the sample count time is 60 minutes then the Strip Background from Spectrum function will subtract 1 6 10 minutes background count time 60 minutes sample count time of the background counts from the sample spectrum Spectrum Techniques UCS 30 33 Data Smoothing Experiment Iso Match
27. THE EXTERNAL HV CONNECTOR WHEN THE UNIT IS OPERATING NEVER REMOVE OR CONNECT CABLES WITH THE INSTRUMENT RUNNING SERVICE BY AUTHORIZED PERSONNEL ONLY PREAMP POWER WARNING POS NEG DANGEROUS VOL TAGES DAK HOSE TENNESSEE S Ra TECHNIQUES 37830 ON HV CONNECTORS MADE IN USA sown E O Re _ Seel AG HIGH VOLTAGE MSB ROI GATE MCS TICOMP USB OUT OUT IN N INPUT T OOOO O DANGEROUS VOLTAGES INSIDE SERVICE BY AUTHORIZED PERSONNEL ONLY Rear Panel Spectrum Techniques UCS 30 CAUTION Be sure to use the correct high voltage polarity for your device to prevent possible damage to equipment POS HIGH VOLTAGE MHV or optional SHV connector supplies positive 0 2048 volt mA maximum current to power scintillation detectors High voltage is fully regulated and computer controlled in 2 volt increments NEG HIGH VOLTAGE Negative High Voltage is an Option If this option is added the UCS30 can also supply negative 0 2048 volt 1mA maximum current to power scintillation detector through an MHV or optional SHV connector High voltage is fully regulated and computer controlled in 2 volt increments Either the POS HIGH VOLTAGE or NEG HIGH VOLTAGE may be selected for use Go to the Settings menu then choose the Amp HV ADC Settings sub menu to gain access to the polarity selection WARNING HIGH VOLTAGE must be OFF before switching between POS HIGH VOLTAGE or NEG HIGH VOLTAGE Failure to comply with this WARNIN
28. VMB2 3 5 635nm 4 2mW C CW VLM2 635nm 4 2mW Circular Beam 1mm 14 7 mm dia 42 12 07 914 none 0221 70 01 Sys VHK2 3 5 635nm 5mW C CW VLM2 635nm 5mW Circular Beam 1 1mm 14 7 mm dia 5 14 07 914 none 0222 021 01 Sys VMB2 3 11 635nm 10mW C CW VLM2 635nm 10 5mW Circular Beam 1mm 14 7 mm dia 10 5 1 3 07 914 none VLM3 650nm 1 6mW Circular Beam 1 3mm Kapton Tape on body for electric 0222 002 01 Sys VLM3 5 2 650nm 1 6mW C SPC isolation Epoxy Back Strain Relief Internal 3 3 volt regulator for protection and stability 9 53 mm dia 17 13 08 914 none Operates at 4 5 6 VDC 0220 99 00 Sys VLM2 1 670nm 1mW 3mm C VLM2 670nm 1mW Circular 3mm Beam 14 7 mm dia 0 95 3 04 914 none pep Beete WW ami C MVP VLM2 670nm 0 95mW Circular Beam 3mm Modulation and Variable Power Control on jay mida Se d m ef ona third lead Recommend 6VDC Operatio 31 0425 000 Sys VLM2 1 670nm 1mW 3mm C Pig VLM2 670nm 0 9mW Circular Beam 3mm with Phono Plug Connector 14 7 mm dia 0 95 3 04 990 pus Molex 0222 81 00 Sys VLM3 1 670nm 1mW C Conn VLM3 670nm 0 9mW Circular Beam 1mm 3 leads with connector Molex 39 01 3029 9 53 mm dia 095 1 1x1 1x07 762 39 01 3029 0221 005 00 Sys VLM2 3 670nm 2 3mW Circ VLM2 670nm 2 3mW Circular Beam 3mm 14 7 mm dia 23 3 04 914 none 0221 831 00 Sys VHK2 5 670nm 4 9mW C VLM2 670nm 4 9mW Circular Beam 1 1mm 14 7 mm dia 49 14 07 914 none 1 of 4 www coherent de
29. an Iso Match library has been loaded If a library has been loaded you can select on of the entries from the window if a library has not been loaded or you want to add an entry to the list enter the name in the second window titled or enter and isotope name Enter the number of peaks you want to add for this isotope in the third box labeled Enter number of peaks 10 max and click on Edit Further dialog boxes will appear that allow you to enter peak s for the isotope DEE Isotope Half Life Cs 1 37 30 years Peak Energy KeV Abundance Add Delete Edit If you want to save the Iso Match to a disk file open the File Menu and click on Save Library Spectrum Techniques UCS 30 30 Strip Background Strip Background View Help Load Spectrum Load Background v Show spectrum Show Background Overlay Spectrum and Background Strp Background from Spectrum Allows the user to load a spectrum and a background and then strip the background from the spectrum Strip Background StripBackground View Help Load Spectrum Load Background The Strip Background option is available only in the File Mode The user may load two files Spectrum and Background and subtract the second file from the first The portion subtracted is based on a time adjustment to the data in the second file For example if the first file was measured with 100 seconds live time and the second file was measured with 200 second
30. appropriate choice of lenses You will notice that while correcting problem 2 you have alleviated to some extent problem 1 It may also help to use a polarizer in front of the He Ne laser Observe the He Ne interference fringes with and without a polarizer The standard recording instrument used with a wavemeter is a frequency counter That will be the first technique to use By measuring the ratio of the fringe frequency from each laser as the mirror on the air rail is moved at a constant velocity one should be able to calculate the frequency of the unknown laser The alternative technique that will be used is to record all the data store them and make appropriate manipulations to determine the number of fringes passed from each laser This is the more direct approach The details on how to take data from the two photodiodes D and D and store it on the computer are given in the Appendix With this data you can count the number of fringes including the partial fringe to calculate the frequency of the unknown laser Summary In this lab you should have learned how the Michelson interferometer can be used as a wavemeter to make precision measurements of a laser s frequency and wavelength You should also try to identify some of the factors which limited the precision of your measurements Additional questions 1 How is the precision of this technique affected by the distance which mirror 1 is translated What does this tell you about t
31. as shown in Fig 3 1 2 Use the gammas from the source kit to calibrate the MCA so that full scale is 3 0 MeV For 1024 channels this would put the Cs 0 662 MeV peak at approximately channel 225 3 Construct a calibration curve as in Experiment 3 1 4 Place the Co source from the source kit at exactly 9 3 cm from the face of the detector Count for a period of time long enough so that the area under the sum peak is 1000 counts This procedure was outlined in Experiment 3 6 23 EXPERIMENT 3 dNEGzG ORTEC EXERCISES a Verify that the energy of the sum peak is 2 507 MeV Subtract the background from the sum peak and verify its sum from Eq 14 b Repeatthis sum peak analysis forthe Na source Figure 3 10 shows the decay scheme for Na and atypical spectrum with the sum peak Na 2 60 y Bt 90 EC 10 1 274 MeV B Annihilation 0 RSC 0 511 Mev 22Ne Bt 0 05 1 274 MeV Sum Peak 1 785 MeV Counts Log Scale Channel Number Relative Fig 3 10 Sum Peak for the Na Source from Source Kit SK 1G EXPERIMENT 3 10 Photoelectric Absorption Purpose The purpose of this experiment is to study the photoelectric absorption of photons and verify the strong dependence of this process on the atomic number of the absorbing material When a gamma of energy lt 150 keV interacts with matter the interaction has a high probability of being photoelectric In the photoe
32. before it gets to the ADC The LLD is often used to block high count signals noise in the low range that are not of interest but require excessive time to sample The ULD may be set up to 102 3 Low level discrimination LLD may be scrolled or directly entered 20 Upper level discrimination ULD may be scrolled or directly entered The ability to switch between positive and negative high voltage polarities is an add on option An alternative method to change the LLD and ULD is to use the mouse to move the triangles under the X axis Move the mouse over the triangle to be moved press the left button drag the triangle and release it where desired The software will not allow the LLD and the ULD to be set outside appropriate ranges Voltage Polarity Spectrum Techniques UCS 30 Input Polarity Some detectors require a positive input polarity This option is only available in PHA Amp In mode 21 Peak Time Shaping Amp H ADC Settings e2 LEE E Kel L Amplifier Peaking Times of 1 2 4 or 8 microseconds are selectable in Amp In mode only Peaking times longer than 1 microsecond are useful with solid state detectors such as Ge Li or HPGE detectors Spectrum Techniques UCS 30 22 Presets Preset Time The real time count and the live time count may be changed using the Preset function Click the Preset Time Button on the toolbar Preset Integral The instrument can be se
33. card Each channel preamplifier has 50 Q input impedance so if the PMT signals are also being monitored on a parallel oscilloscope the channel input impedance should be set to 1 M Apply 5 VDC power to the QuarkNet card by plugging the AC adapter into a wall socket A blinking LED associated with each channel indicates the occurrence of a local trigger The LEDs can give a rough visual guide to assist in configuration Note the digital counter is of little value Open the LabVIEW program Setup vi Card Timing Triggering can be initiated by either 1 one pulse from a single PMT or 2 coincident pulses from 2 3 or 4 PMTs Coincident triggering is more reliable because it is less susceptible to false signals produced by random background noise This experiment has two PMTs available to monitor photons in the scintillator tank If coincident triggering is used the time overlap window coincidence time must be set The default value is 40 ns At the default setting two PMTs must produce individual pulses that exceed their specified threshold voltage AND occur within 40 ns of each other to create a trigger If the coincidence time is too short relatively few card triggers will occur If it is too long there is increased probability of false triggers The oscilloscope display of the pulses can guide this setting The coincidence time has no meaning in the single trigger configuration Once the card triggers all the detector input channels wil
34. delay Calibrate the full scale of the TAC MCA If you take data sets with different TAC time windows you will need to calibrate for each TAC setting Remember to calibrate the TAC MCA immediately before or after your data run i e before you inadvertently change something DELAY STOP PULSER DIVIDER TAC MCA START FIG 4 Arrangement for time calibration of the TAC MCA The recommended technique to analyze the data is to extract a spread sheet file from the MCA to manipulate and fit the data You will need to correct for background counts Remember if your time bins become too wide then the simple 1 exponential form is no longer correct How does 2 8 your measurement compare with the world average of z 2 197 us If you agree within 5 10 you are measuring the Fermi coupling constant to that same precision 2 Dedicated Board Based Measurement The QuarkNet card was designed and built by engineers at Fermilab in Batavia Illinois to replace traditional NIM A single circuit board amplifies PMT signals by 10x and uses voltage comparators for discrimination with adjustable threshold On board timing is implemented with CPLD Complex Programmable Logic Device via software installed at Fermilab Photon events are time resolved with an accuracy of 1 25 ns using a time digital converter A micro controller interfaces with the control PC using a custom LabVIEW program Connect the PMT outputs to two detector input channels on the QuarkNet
35. either Internal or External source for initiating the strobe cycle to strobe valid information from the TAC and SCA outputs START GATE MODE Two position locking toggle switch selects Coincidence or Anti coincidence mode of operation for the Start circuitry Start circuitry is enabled in the Coinc position or inhibited in the Anti position during the interval of a Start Gate input signal STOP GATE MODE Two position locking toggle switch selects Coincidence or Anti coincidence mode of operation for the Stop circuitry Stop circuitry is enabled in the Coinc position or inhibited in the Anti position during the interval of a Stop Gate input signal SCA WINDOW AT 10 turn precision locking potentiometer sets the SCA upper level dis criminator threshoid from 0 05 V to 10 05 V Tove tho wert zwei serting SCA LOWER LEVEL T 10 turn precision locking potentiometer sets the SCA lower level discriminator threshold from 0 05 V to 10 05 V TAC INHIBIT Two position SE toggle switch In the Inhibit position the TAC output is available only if the output amplitude is within the SCA window In the Out position the SCA has no effect on the TAC output CONTROLS Rear Panel EXT STROBE RESET Two position locking toggle switch allows the converter to be reset nominally 10 us or 100 us after an accepted Stop input signal if an Ext Strobe signal has not been received INPUTS All six front panel inputs listed below are dc coupl
36. exter nal strobe signal to further enhance its versatility The single channel analyzer section of the Model 567 allows the expert menter to place very specific time restrictions on the timing spectrum The SCA is operated in the Window position where the upper level dis criminator setting is added to that of the lower level discriminator The SCA output pulse width is equal to the time from the occurrence of the TAC output until the end of the reset pulse or the end of the TAC output The syn chronization of the SCA output with the stop input virtually eliminates any time walk in the SCA output All Model 567 inputs are printed wiring board PWB jumper selectable to ac cept either negative or positive NIM standard signals All inputs and out puts are dc coupled so that changing input count rates will not hinder nor mal operation of the Model 567 The TAC output should be connected to the dc coupled input of a multichannel analyzer MCA for optimum high count rate performance 567 SCA b e e For time spectroscopy in the range from 10 ns to 2 ms coincidence experiments e Valid Start and Valid Conversion outputs Selectable output delay and width Output synchronized with a stop or external strobe signal stop input signals Positive or negative input signals Includes SCA to set a time window for Provision to reject unwanted start or 567 Time to Amplitude Converter SCA c
37. form to the shop foreman on your first day of the Mechanical Practices Lab Machine Shop Practices During the first class period you will go to the machine shop and be introduced to the basic equipment by one of the machinists Over the course of the remaining 4 weeks under the machinist s supervision you will then each fabricate a fun two slider hand crank device of which a 3D CAD drawing is shown below A mechanical drawing of the hand crank device assembly and the parts you will fabricate is also appended to this write up Print out hard copies of these drawings and bring them with you to the first lab period so you can refer to them while in the shop Drawings for all parts except two are supplied You will be responsible for making a complete machine drawing of 1 The brass knob for which you will need to include critical dimensions such as major and minor diameter of the 3 8 16 UNC 2A thread and 2 The brass nut which is a 3 8 16 hex jam nut Use the drawings for the other parts and the Building Scientific Apparatus text on reserve in Centennial Library as guides on how to make the drawing of the knob and nut Refer to the Machinery s Handbook also on reserve in the Centennial Library for the necessary dimensions and tolerances of the nut and thread on the knob Complete these drawings and have your instructor check them by no later than the beginning of the 3 class period Fabrication of the hand crank device will require you wi
38. give an opportunity to cancel the request Once accepted the changes are made and cannot be undone Click on Yes to reset defaults or on No to cancel the operation Strip Background Load Spectrum Load Background Show spectrum Show Background Overlay Spectrum and Background Strp Background from Spectrum Allows the user to load a spectrum and a background and then strip the background from the spectrum Strip Background 1 Strip Background View Help Load Spectrum Load Background Show spectrum Show Background Overlay Spectrum aid Backaround Strip Background from Spectrum Spectrum Techniques UCS 30 45 TS SF EEF The Strip Background option is available only in the File Mode The user may load two files Spectrum and Background and subtract the second file from the first The portion subtracted is based on a time adjustment to the data in the second file For example if the first file was measured with 100 seconds live time and the second file was measured with 200 seconds live time then the data in the second file is divided by 2 200 seconds 100 seconds before it is subtracted Background Subtraction This is a special case of spectrum stripping Collect a background sample spectrum usually for a long collection time Load this spectrum as Background and click on Strip Background from Spectrum The live time fraction of the background is subtracted from spectrum This provides
39. linear range of O to 10 V active filter shaped dc restored dc level adjustable to 15 mV BI Front panel BNC connector with Z 1 Q and rear panel connector with Z 93 Q short circuit proof positive lobe leading and full scale linear range of 0 to 10 V active filter shaped PREAMP POWER Rear panel standard ORTEC power connector Amphenol 17 10090 mates with captive and noncaptive power cords on all ORTEC preamplifiers ORDERING INFORMATION Model Description 575A Amplifier Alliance Partners Press Release Conf amp Meeting Schedule Careers Quality Policy Privacy Statement Copyright 2007 Advanced Measurement Technology Inc AMETEK 2 of 2 2 15 08 7 51 AM LAB 5 Speed Measurement by Optical Techniques J C Diels and W Rudolph Purpose Familiarize the student with the Doppler effect as used for speed measurement spatial filtering spectrum analyzers and interferometric techniques Reading Assignment As referenced in text and Chapter 4 of Building Scientific Apparatus 3rd edition by John Moore et al Perseus Books Cambridge MA 2003 Introduction The most obvious optical method for measuring the speed of a moving object is to use the Doppler effect light reflected from the moving object will be shifted in frequency in proportion to the line of sight velocity of the object While we are familiar with examples in the radio domain such as police traffic radar and Doppler weather radar and
40. mA 12 Volts Q 165 mA 24 Volts 80 mA 115 Volts AC 65 mA 12 Volts 6 Volts 415 mA 0 mA 24 Volts 80 mA NOTE All currents are within NIM specification limits permitting a full powered bin to be operated without overloading Operating Temperature O C to 70 C ambient Packaging Standard single width NIM module in accordance with TID 20893 and section ND 524 Quality Control Standard 36 hour cycled burn in with switched power cycles Options Call Phillips Scientific to find out about available options MODEL 705 OCTAL DISCRIMINATOR FRONT PANEL DESCRIPTION Standard 1 NIM Packaging in accordance with TID 20893 Threshold Control 15 turn Screwdriver Adjustment Variable from 25 mV to 1 Volt 50 Ohm Input Threshold Monitor Test Point provides a DC Voltage 10 times the actual Threshold Setting 250 mV to 10 V One Complemented NIM Output Quiescently 16 mA 800 mv Goes to 0 mA 0 Volts during output Output Width Control 15 turn Screwdriver Adjustment Variable from 6 nSec to 150 nSec Double amplitude bridged output 32 mA 1 6 Volts across 50 ohms 8 Volt with two 50 ohm terminations Fast Inhibit Input accepts normal NIM logic 500 mV 50 Ohm Impedance Linear summed output Voltage and Current SE NOTE Bin Gate Enable Requirements Disable Switch on Rear Panel permits Inhibiting via Bin Connector Phillips Scienti
41. mill922 2 5 where 7 is the muon lifetime and G is the Fermi coupling constant The Fermi coupling constant is the fundamental coupling constant of the charge changing weak interaction Thus a measurement of the muon lifetime provides a measurement of G once the muon mass is known A fraction of the muons that reach the earth s surface have just the correct energy to stop in a block or tank of scintillator As the muons stop they deposit 2 MeV gm cm in the scintillator Because the density of scintillator is 1 gm cm muons deposit 2 MeV cm of path length This is much greater than the 1 MeV cm of typical y rays in Part 1 of this lab Thus these stopping muons result in a pulse of light in the scintillator which is easily detected Roughly 5 of the w will be captured into low Bohr orbits and then interact with the nucleus of the scintillator atoms before decaying Thus the majority of w and virtually all the stopped u decay before interacting with electrons or nuclei in the scintillator Each muon decay results in an electron with a energy up to m 2 53 MeV i e neutrinos are essentially massless These electrons also can result in a pulse of light in the scintillator which is also easily detected If one starts a clock each time a muon stops i e this defines z 0 then for a total of Np stopped muons the number of muons remaining at a time t later is N t IN uo exp t t Note clearly this assumes that muon
42. of the experimental setup and the speed is then given by the product of this spacing and the characteristic frequency of the scattered light fluctuations For this part of the experiment a rotating disk will again be used although a much faster rotation rate is required for the effect to be readily observable 5 1 Theory and Concepts At this point the question arises How do we get around the problems mentioned in the introduction The answer is a technique known as heterodyne interferometry This method involves combining the frequency shifted or modulated optical or radio microwave etc signal with an unshifted reference signal The so called square law detector which includes all common optical detectors will respond only to the intensity and intensity variation of the combined beam If the frequencies of the two signals differ by less than the bandwidth of the detector and are not identical the electrical output of the detector will be modulated at a frequency equal to the difference between the frequencies of the two beams For simplicity let us assume two electromagnetic waves of equal amplitude A and frequencies o and o If the two waves are incident on a detector we measure a signal S Acoso t Acosa t 2 1 where denotes averaging performed by the detector and subsequent electronics Using the identity 2cosw t cos t cos t cos t we can write the signal as S A cos ct A
43. of the PMT output pulses must be sufficiently above the background noise and at a level where they can be readily discriminated Initial setup should be performed with single detection a gate width of 100 ns and 100 mV threshold Negative voltage for all PMT signals is assumed so the threshold is entered as a positive number These settings are not critical but should be a good starting point The sampling period should be long enough that the count does not vary widely between display updates Start the program wait three seconds for the card to initialize and press the RUN button Detector counts will be displayed To change an operating parameter press PAUSE make the desired change then press RUN The PAUSE button allows parameters to be modified without a complete card reset As the threshold voltage increases the count rate should drop When higher thresholds do not noticeably reduce the count rate a good operating threshold voltage is identified Keep the PMT voltage constant and configure the second channel using the same criteria If adequate thresholds can t be established on both channels the PMT voltage must be changed Select the coincidence tab to enable single counting from both PMTs and display their coincidence counts Both detectors should be counting at a higher rate than the coincidence events you can also determine which of the two detectors is limiting the coincidence trigger rate Proper behavior verifies the threshold
44. read out of the MCA erase it and replace the Cs source with a Co source from SK 1G 5 Accumulate the spectrum for a period of time long enough for the spectrum to be similar to that in Fig 3 3 6 Read out the MCA EXERCISES a Plot both the Cs and Co spectra and fill in items 1 2 and 3 in Table 3 1 b From items 1 2 and3in Table 3 1 make a plot of energy of the photopeaks vs channel number Figure 3 4 shows this calibration for the data taken from Figs 3 2 and 3 3 If other calibration sources are available additional data points can be added to Fig 3 4 The other entries in Table 3 1 will be filled out in Experiment 3 3 C Usethe energy calibration feature of the MCA and com pare the results with those found in Exercise b PHOTOPEAK CHANNEL 280 FWHM 32 CHANNELS E COMPTON EDGE Channel Number Fig 3 2 Nal TI Spectrum for Cs 16 EXPERIMENT 3 350 300 250 BACKSCATTER 200 Counts Channel 150 100 Event Energy MeV Channel No 50 Photopeak 1 33 560 Photopeak 1 17 496 Backscatter 70 210 80 l l l he i T 1 17 MeV PEAK COMPTON EDGE for 1 33 MeV o 80 160 240 320 400 480 560 640 Channel Number Fig 3 3 Nal TI Spectrum for Co Table 3 1 _ o a 5 o NM EXPERIMENT 3 2 Energy Analysis of an Unknown Gamma Source Purpose The purpose here is to use the calibrated system of Experi
45. signals are in time on average Set the coincidence unit to require a 2 fold coincidence The coincidence requires that both PMTs are above threshold to avoid noise triggers or triggers from cosmic ray muons that are clippers To monitor and set up your experiment pass signals of interest through the scope i e put the oscilloscope between outputs of interest and the next device in the logic signal chain DISCRIMINATOR COINCIDENCE CIRCUIT DISCRIMINATOR Fig 2 A practical experimental arrangement for the muon lifetime experiment Two outputs are taken from the coincidence unit One is delayed and used to START the TAC The other is used to STOP the TAC For details on how a TAC works see Appendix 1 At first this order appears to be counter intuitive This is explained by Fig 3 and by the fact that only when the TAC receives a good START STOP combination will it produce an output pulse To 2 7 delay the signal to the TAC START use the delay box supplied with the experiment How much delay should be introduced Thus all the events that have a START but no STOP within the TAC time window will result in no TAC output For events with a good START STOP combination the TAC output pulse has an amplitude proportional to the difference in time between the START and STOP The TAC output signal is analyzed in the MCA This is the good news The bad news is that if a second muon passes through the scintillator close in time to first then
46. stability of the 60 Hz network is fairly good However the error in the reducing gears and lead screw of the translation stage make it impossible to achieve uniform translation speed In fact a chart recording of the fringes of an interferometer using a synchronous motor driven translation stage will indicate periodic changes in wavelength which can be used to identify the gear sizes and defects in the reduction box Therefore a simple way to determine the quality of such a drive mechanism is to record closely spaced fringes chart the motor on a low speed relative to the periodicity of the interferences and copy them on a transparency The Moire pattern observed when the transparency is superimposed on the original recording is an indication of the speed variations in the motor drive So how then can we determine d with the required precision The answer seems almost circular use the laser It is usually the frequency of a laser which is known with the most precision The absolute frequency of many well stabilized lasers has been determined by beating its frequency down in a long chain of complicated nonlinear mixing devices to a range in which it can be compared with the current definition of time the ground state hyperfine splitting of cesium which is 9 192 631 770 Hz As of 1983 the speed of light has been defined to be 299 792 458 m s Thus by knowing the precise frequency of the laser and using the defined value for the spee
47. take Laser Diode Module with leads and add the connector to work with the EEN Plug 3 5mm Stereo LabLaser 31 1001 or 31 1050 power supplies Modulation Cable to connect LabLaser Laser Diode Module with installed Modulation Option to 31 1068 000 Cable Modulation LabLaser BNC the 31 1050 000 Power Supply The power supply front panel knob will not control the laser power Laser is controlled via BNC input on Modulation Cable Neben einer Auswahl von standardisierten Laserdiodenmodulen im violetten und roten Bereich bietet COHERENT auch kundenspezifische L sungen f r Ihre OEM Anwendung Die typischen Wellenl ngen im roten und nahen infraroten sowie auch im violetten Bereich k nnen mit verschiedenen Strahlprofilen Geh usen und Verkabelungen kombiniert werden Die jeweiligen Module sind CE zertifiziert und den entsprechenden Laserklassen zugeordnet Auch bei den OEM Modulen setzen wir unsere patentierte Microblaze Technologie ein um runde Strahlprofile mit einem M2 1 1 zu erzeugen Eine einstellbare Fokussier Optik kann ebenfalls in die Module integriert werden In vielen F llen kann so der bisher eingesetzte HeNe Laser durch ein kosteng nstiges kompaktes Diodenmodul ersetzt werden Um Ihren speziellen Anforderungen im industriellen aber auch im wissenschaftlichen Bereich gerecht zu werden sind folgende Eckdaten wichtig um eine optimal angepasste L sung zu finden Leistung und Strahlprofil Rund Elliptisch Linie D
48. that the pulses are gt 50 100 mV Typically positive 1200 V is adequate high voltage do not exceed 1500V Before continuing it is Instructive to see the y ray line s directly on the oscilloscope Each line will appear as a brighter band To see this you will need to get the correct trigger polarity negative if you take the signal from the anode output of the PMT base or positive if you take the 2 2 signal from the dynode output of the PMT base You will also need a sweep rate that is matched to the time response of the Nal T1 detector Once you find the signal vary the high voltage modestly to see how the signal magnitude varies with applied high voltage At this point you may want to determine what voltage change will cause a doubling of the signal amplitude The UCS 30 MCA also has an integral preamp and amplifier Following the manual Appendix 3 for the MCA connect it to the output of the PMT For simple applications you should set the MCA to accumulate display the maximum number of channels The final choice of high voltage and amplifier gain settings should place the highest energy y ray line near the upper end of the MCA range As different combinations of high voltage and amplifier gain will result in the same amplitude signal you may want to investigate which combination gives you the sharpest signal i e the narrowest line for a fixed signal amplitude At this point you should also accumulate y ray spectra from the Co sou
49. the PMTs when either the 10 X attenuator discussed below is not in place the box lid is not closed or the inner PMT enclosure is not closed In addition if not all of these conditions are met the electronic shutters on the inner PMT enclosure will not be open FIXED PMT HOUSING ATTENUATOR COVER SLID BACK Figure 1 Photograph of the light tight box containing the experimental apparatus A secondary light tight box encloses the 2 PMTs 3 Photon Detector The detectors used in this experiment are two Hamamatsu R1527 photomultiplier tubes PMTs specifications in the Appendix This photomultiplier was chosen its quantum efficiency at 543nm and its large signal to noise ratio A high voltage source of LESS THAN 1200 V is applied to the PMTs The size of the detector window on the PMT is a couple of centimeters in length however the interference fringe measurement requires sub millimeter spatial resolution Therefore a single 50 um entrance slit in a 1 fixed lens mount is placed in front of PMT 1 and both are mounted on a translation stage This provides the required spatial resolution as the detector and entrance slit can be translated across the interference pattern while measuring the photon flux Both PMTs have been enclosed in a secondary light tight box and in a magnetic shield thereby limiting their field of view to background and scattered photons The PMTs are extremely sensitive to light they count single photons Norma
50. the STEP keys which usually change the parameter by a factor of 2 or in a 1 2 5 10 or 1 3 10 sequence or by numerical entry from the keypad If the new value is not allowed a bell will sound and possibly an error message will be displayed the parameter will remain highlighted awaiting an acceptable entry A change implemented by the STEP keys will be effected immediately while a numerical entry will not take effect until an appropriate unit is entered In either case the CRT entry will remain highlighted until a units key has been pressed 3 SWEEP The SWEEP ie the scanning of the internal reference oscillator through the appropriate range of frequencies may be either CONTinuous a new sweep beginning as soon as the last one is completed or SINGLE sweeping stops when the STOP FREQ is reached In either case the SWEEPING light will be lit and the CRT trace will be continually updated while the sweep is in progress The MANUAL ENTRY mode is rarely useful 4 TRACE The 3585A can store two traces A which is continually updated during sweeping and B which can be used for permanent storage A trace must first be obtained in the A trace then it can be transferred to B by pressing the STORE A B key Either or both can be viewed at any time as can their algebraic difference A B by activating the appropriate key The B trace is particularly useful for storing a good trace for later plotting or for storing baseline noise trace which can th
51. the counter is summing the counts under the photopeak You should ob serve the MCA for each spectrum to make sure that the proper spectrum is being stored 4 Repeat step 3 for each added absorber thickness that was used in Experiment 3 7 Make a background run with the source removed and fill in Table 3 4 as in Experiment 3 7 Table 3 4 Absorber Thickness mg cm 3 DECHE 5 Calculate the same data as in Experiment 3 7 Exercises aand b 6 In step 2 the output of the MCA was read Sum this output spectrum and compare it with the counter sum that was taken from the same run The counter sum should be slightly larger since it does not suffer from dead time corrections at these counting rates The MCA does suffer because it re quires some amount of time to measure and store each pulse and thus does not actually analyze as many pulses as have been furnished to it The MCA sum should be equal to the counter count times the percent of live time which is equal to the live time of the MCA divided by the clock time for the spectrum accumulation EXPERIMENT 3 9 Sum Peak Analysis Figure 3 3 shows the two pronounced peaks in Co Figure 3 9 shows the decay scheme of Co Most of the time the decay occurs by B emission to the 2 507 MeV excited state of Ni Subsequent decay to the ground state always occurs by gamma emission to the 1 3325 MeV level a 1 174 MeV gamma followed almost simultaneously by the 1 3325
52. this task The limited drawing required for this module will only require pencil graph paper a scale a right triangle and a compass Feel free to use computer software to make the drawing if you have some available 1 1 Shop Safety The first class session on will be spent will be spent in the shop actually applying some of the fabrication techniques about which you have been reading Of utmost importance is your safety in the shop While you are working in the shop it is REQUIRED that you 1 Wear safety glasses at all times Do not wear open toe shoes such as sandals or flip flops Secure or tie back loose clothing and long hair Remove all jewelry especially includes rings watches and necklaces Only use brushes to remove metal chips from machines Do not use compressed air to clean yourself or the machines Do not use earbuds iPods cell phone or other portable devices Do not use machine tool practices that are not approved by the instructor Focus on the work you are doing 10 Do not work in the shop while under the influence of drugs or alcohol This includes any prescription drugs which could cause drowsiness lightheadedness or disorientation If you have a question it is much better to ask the shop personnel for help than to proceed with an operation with which you are unfamiliar Appended is a form to read and sign acknowledging you have read and understood the aforementioned safety rules Give the signed
53. to DC converter type high voltage power supply SIGNAL GND o SIGNAL OUTPUT RG 174 U BLACK o POWER SUPPLY GND AWG22 BLACK Rto R10 330kQ C1 to C3 0 01 uF o HV AWG22 VIOLET Ri to Rio 330k Q Ci to C3 0 01 F TACCA0002ED HAMAMATSU HAMAMATSU PHOTONICS K K Electoron Tube Center 314 5 Shimokanzo Toyooka village Iwata gun Shizuoka ken 438 0193 Japan Telephone 81 539 62 5248 Fax 81 539 62 2205 U S A Hamamatsu Corporation 360 Foothill Road Bridgewater N J 08807 0910 U S A Telephone 1 908 231 0960 Fax 1 908 231 1218 Germany Hamamatsu Photonics Deutschland GmbH Arzbergerstr 10 D 82211 Herrsching am Ammersee Germany Telephone 49 8152 375 0 Fax 49 8152 2658 TACCAO0064EA Warning Personal Safety Hazards Electrical Shock Operating voltages applied to this device present a shock hazard France Hamamatsu Photonics France S A R L 8 Rue du Saule Trapu Parc du Moulin de Massy 91882 Massy Cedex France Telephone 33 1 69 53 71 00 Fax 33 1 69 53 71 10 United Kingdom Hamamatsu Photonics UK Limted Lough Point 2 Gladbeck Way Windmill Hill Enfield Middlesex EN2 7JA United Kingdom Telephone 44 181 367 3560 Fax 44 181 367 6384 North Europe Hamamatsu Photonics Norden AB F r gatan 7 S 164 40 Kista Sweden Telephone 46 8 703 29 50 Fax 46 8 750 58 95 Italy Hamamatsu Photonics Italia S R L Via Della Moia 1 E 20020 Arese Milano Italy Telephone 39 2
54. to an electron Two voltage pulses appear on the scope You will measure the lifetime of the muon using two different approaches for the electronics package shown in Figure 1 The first is based upon Nuclear Instrumentation Module NIM electronics Although no longer routinely used to accumulate the final data in modern particle physics experiments it is often still used to set up such experiments as it allows for oscilloscope validation of each step of the experiment upon which a dedicated board can then be designed fabricated and used The second method you will use to measure the muon lifetime is with just such a dedicated board By making the measurement using both approaches you will see the individual measurements made in nuclear particle physics via NIM instrumentation and how present day experiments are conducted with dedicated boards 1 NIM Based Measurement A sketch of a realistic experimental setup is shown in Fig 2 The PMTs require negative HV and 1500 V or less should provide adequate output signals In practice you need to adjust the HV for each PMT to get approximately the same output signals Typically the PMT output signals are discriminated with Vesna 30 mV Set the discriminator output pulse length to 20 ns Are the pulse lengths sufficient to allow for the variation in pulse timing between the 2 PMTs and still give a coincidence Have you adjusted the relative time delay between the two scintillator signals so the
55. with a large number of slow rise time signals will most likely give poorer results ELECTRICAL AND MECHANICAL Power Required 12 V 55 mA 24 V 40 mA 12 V 70 mA 12 V 75 mA Weight Net 1 5 kg 3 3 Ib Shipping 3 1 kg 7 0 Ib Dimensions Standard single width NIM module 3 43 x 22 13 cm 1 35 x 8 714 in per DOE ER 0457T CONTROLS FINE GAIN 10 turn precision potentiometer with graduated dial for 1 of 2 2 15 08 7 51 AM Amplifier Specifications ORTEC 575A http ortec online com electronics amp 575a 20spec htm continuously variable direct reading gain factor of X2 5 to X12 5 COARSE GAIN 6 position switch selects feedback resistors for gain factors of 2 4 10 20 40 and 100 SHAPING TIME 3 position printed wiring board PWB jumpers easily accessible through side panel select time constants for active pulse shaping filter network from 0 5 1 5 and 3 us POS NEG Toggle switch selects either Pos or Neg input pulse polarity PZ ADJ Screwdriver adjustable potentiometer to set the pole zero cancellation to compensate input decay times from 30 us to infinity INPUTS BNC front and rear panel connectors accept either positive or negative pulses with rise times of 10 to 650 ns and decay times of 30 us to infinity Zi 1000 Q dc coupled linear maximum 2 V absolute maximum 20 V OUTPUTS UNI Front panel BNC connector with Z lt 1 Q and rear panel connector with Z 93 Q short circuit proof full scale
56. 15 5 Linear las use PSU 31 2405 s4 2405 000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 4mW Random 0 80mm Beam Length 396mm Diameter LSR Red HeNe 4mW 15 5 Random de usa PSU 31 2405 Eesen Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Sp Helium Neon Laser Red 632 8nm 7mW Linear 1 02mm Beam Length 456mm Diameter LSR Red HeNe 7mW 18 Linear stram use PSU 31 2454 5123454000 Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 7mW Random 1 02mm Beam Length 456mm Diameter LSR Red HeNe 7mW 18 Random aiT uso PSU 31 2454 312454000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 10mW Linear 0 46mm Beam Length 484mm Diameter LSR Red HeNe 10mW 19 Linear latSrom use PSU 31 2439 31 2439 000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 10mW Random 0 46mm Beam Length 484mm Diameter LSR Red HeNe 10mW 19 Random de use PSU 31 2439 31 2439 000 Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC 1 Helium Neon Laser Red 632 8nm 17mW Li
57. 23458 than 0 in preset integral will cause the system to STOP counting when the total counts of all the channels within the ROI Cancel reaches that value Go Stop and Erase Go Stop and Erase functions are accessed with the Tool Bar buttons Clicking on Start le E begins data collection Clicking on Stop ends p data collection Clicking on Erase sets each channel s data to zero Additionally three hot key combination are defined as shortcuts for data acquisition functions Pressing the appropriate action key while pressing the Cl and Shift keys will provide Go Stop and m p Erase action To Go press Ctrl Shift A to Stop press Ctrl Shift S and to Erase press Ctrl Shift E Region of Interest ROD Region of interest ROD selection is an advanced feature which provides instantaneous computation of peak gross and net counts These values may be used along with isotope decay tables and detection efficiency to calculate absolute or relative isotopic activities ROIs must not overlap and need to be separated by at least one channel for correct area calculation Up to 16 different ROIs are possible using the color selector from the pull down Settings menu Spectrum Techniques UCS 30 24 5 1 1 1 Set ROI To set an ROI around a peak click the ROI button on the Tool Bar Click the left mouse button at the beginning of the ROI hold down the left mouse button and drag the marker to the other side of the peak r
58. 24 V 60 mA 24 V 35 mA 115 VAC 60 mA Note All currents within NIM specifications limits allowing a full powered bin to be operated without overioading Operating Temperature O C to 70 C ambient Packaging Standard single width NIM module in accordance with TID 20893 and Section 524 Options Call Phillips Scientific to find out about available options MODEL 755 QUAD FOUR FOLD MAJORITY LOGIC UNIT FRONT PANEL DESCRIPTION Standard 1 NIM Packaging in accordance with TID 20893 Output Width Control l5 turn Screwdriver Adjustment Variable from U i 4 nSec to 1 uSec Four Logic Inputs Accepts Normal NIM Logic 500 mV 50 ohm Impedance Two pairs of bridged outputs each pair delivers 32 mA 1 6 Volts across Level Switch Seiects 50 ohms 8 Volt with Logical OR AND both outputs 50 ohm or Majority Logic terminated Functions i Four Position Coincidence One Complemented NIM Output Quiescently 16 mA 800 mV Goes to 0 mA 0 Volts during output Fast Inhibit Input accepts normal NIM Logic 500 mV 50 ohm Impedance NOTE Bin Gate Enable Voltade ang turrene Disable Switch on Rear Requirements Panel permits Inhibiting via Bin Connector Phillips Scientific 13 Ackerman Avenue Suffern New York 10901 USA 914 357 9417 LAB 3 493L Experiment Development Laboratory Paul R Schwoebel Special
59. 3 1 113 PREAMPLIFIER that leave the source per unit of time In this experiment the student will become familiar with some of the basic Nal TI measurements associated with gamma emitting unknowns A total time of 6 h is required to complete all the parts of Experiment 3 3 1 through 3 10 The complete series can be done in two 3 h lab periods since each is written to be fairly independent of the others EXPERIMENT 3 1 Energy Calibration Setup of Equipment Set up the electronics in the arrangement shown in Fig 3 1 There are two parameters that ultimately determine the over all gain of the system the high voltage that is furnished to the phototube and the gain of the linear amplifier The gain of the photomultiplier tube is quite dependent upon its high voltage A rule of thumb for most phototubes is that a 1096 change of the high voltage will change the gain by a factor of 2 The high voltage value depends on the phototube being ACE 2K MCA System 575A AMPLIFIER Electronic Block Diagram for Gamma Ray Spectroscopy System with Nal T Detector 15 EXPERIMENT 3 die EGsG ORTEC used consult your instruction manual for the phototube and select a value in the middle of its normal operating range The instructor may wish to recommend a value Set the indicated modules as follows 556 High Voltage See phototube instructions and set the level at about the middle of the acceptable operati
60. 8 mn 44 5 ma dis 2 1 25deg x pin nns Degree Fan Angle Adjustable pomme Sys FLG2 3 30Deg 635nm 1mW Adj VLM2 Line Generator 635nm 1 2mW Adjustable Focus Line Width 30 Degree Fan Angle Label 17 wm 14 5 mm dia De 30deg x 609 m lon module body Adjustable keen Sys FLG2 3 60Deg 635nm 2mW Adj VLM2 Line Generator 635nm 1 8mW Adjustable Focus Line Width 60 Degree Fan Angle Label i wm 14 5 mm dia T 4 60deg x m e on module body Adjustable 2 of 4 www coherent de D e Item Number Description Extended Description 1062083 Sys LabLaser 830nm 25mW E MVP LabLaser 830nm 25mW Elliptical Beam 5 2 x 2 1mm CW Phono Plug Connector 19 22 mmdiax142mm 25 52x21 02x06 1140 stereo 0221 159 00 Sys Indust 670nm 4mW E CW Industrial Laser Diode Module 670nm 4 2mW Elliptical Beam 3x1mm 19 22 mmdiaxi42mm 42 3x1 03x 1 0 304 none 0221 173 00 Sys Indust 670nm 2 5mW E CW Industrial Laser Diode Module 670nm 2 5mW Elliptical Beam 3 2 x 1 0mm 19 22 mmdiax142mm 25 3 2x1 0 0 3x 1 0 173 none 31 0102 000 Sys LabLaser 635nm 4mW E CW LabLaser 635nm 4mW Elliptical Beam 5 6 x 1 5mm CW Phono Plug Connector 19 22 mmdiaxi2mm 4 2 56x15 02x07 990 chon m ISys LabLaser 635nm 4mW E MVP LabLaser 635nm 4mW Elliptical Beam 5 6 x 1 5mm Modulation and Variable Power Control 49 55 mmdiaxia2mm 42 56xts 02x07 ogo Phono Phono Plug Connector S
61. 935 81 733 Fax 39 2 935 81 741 TPMS1007E02 OCT 1994 Gesamtubersicht Laser Diode COHERENT Coherent GmbH Modules LDM amp HeNe Lasers Item Number 1053595 Description Radius 375 8 375nm 8mW CDRH Extended Description Radius 375nm 8mW CDRH 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 1000 5 Pin DIN 1053594 Radius 375 8 375nm 8mW OEM Radius 375nm 8mW OEM 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 1000 5 Pin DIN Item Number Description Extended Description 1053310 Radius 405 4 405nm 4mW OEM Radius 405nm 4mW Adjustable Focus OEM Vioflame 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 42 47x16 02x03 1000 5 PinDIN 1051390 Radius 405 25 405nm 25mW CDRH Ke 405nm 25mW Adjustable Focus with CDRH Control Box 4 6mm Olametar 218mm 1 A 5 mm gig mia mm 25 47x16 02x03 1000 5 Pin DIN 1043000 Radius 405 25 405nm 25mW OEM Radius 405nm 25mW Adjustable Focus OEM 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 25 4 7x1 6 02x03 1000 5 PinDIN 0223 023 00 Radius 405 25CC 405nm 25mW CC Bee SW Constant Current ee el EE 25 47x16 02x03 1000 5 Pin DIN 1051505 Radius 405 30EP 405nm 30mW CDR Radius 405nm 30mW Extra Photodiode for power stability and low noise with CDRH Control Box 44 5 mm dia x218 mm 30 29x10 02x04 1000 s Pin DIN 1008553 Radius 405 30EP 405nm 30mW OEM Radius 405am 30mWy Extra Photodiade fo
62. ADC Settings e2 LEE E Kel L Adjustments may be made to the amplification high voltage conversion gain low level discriminator and the high level discriminator Selecting OK will cause these values to be written to the UCS 30 instrument Spectrum Techniques UCS 30 17 Configuring System Parameters Once the program is running it will be necessary to configure the system parameters for correct operation and calibration Place a gamma emitting check source near the detector face Cesium 137 Cs 137 is a good choice It has a single peak at 662 keV Click on Settings then click on Amp HV ADC Set the high voltage to the voltage as listed by the detector manufacturer As an example set the high voltage to positive 600 volts click ON DO NOT exceed the maximum high voltage rating of the detector usually 1200 volts Set the amplifier COARSE GAIN to 8 and set the FINE GAIN to 1 as a starting position Click on OK to set adjustments and exit the menu Start the data acquisition and adjust the amplifier gain until the 662 keV peak is approximately mid scale Once the acquisition is started you may enter the Amp HV ADC menu and make adjustments while viewing the spectrum This will allow you to position the peak in the desired channels Spectrum Techniques UCS 30 High Voltage Amp H ADC Settings feo e e e d T e E d bes uU m High Voltage may be entered directly
63. Also you may need to change the CENTER SPAN or START STOP frequencies to keep the signal on the trace Similarly the RBW VBW and dB DIV may need to be adjusted to suit the signal If you have problems with spurious signals the A B feature is very useful 5 11 LAB 6 The Wavemeter J C Diels and W Rudolph Purpose Familiarize the student with the Michelson interferometer gaussian beams and the transformation of gaussian beams by lenses Reading Assignment As referenced in text and Chapter 4 of Building Scientific Apparatus 3rd edition by John Moore et al Perseus Books Cambridge MA 2003 Background The goal of this experiment is to utilize the sensitivity of the Michelson interferometer used here in a wavemeter to precisely determine the frequency and wavelength of an unknown laser Due to the wavelike nature of light the basic Michelson interferometer as depicted in Fig 1 produces dark and bright fringes at the photodetector PD as the length of one arm is continuously varied by an amount A These fringes are the result of constructive and destructive interference of the fields from each arm of the interferometer For a more detailed description of the Michelson interferometer see Hecht Theory The intensity at the output of a Michelson interferometer see Fig 1 that is recorded by the photodiode is given by I 1 2 1 cos 2a d d A The photodetector will see one fringe go by for a displace
64. CS20 Live Mode Channel 482 Time 966 sec Counts 13 Dwell 2 sec UCS20 MCS Spectrum shown UCS30 similar Multi Channel Scaling mode is used for measuring time related phenomena such as half life decay or single photon counting The ADC is bypassed and incoming events are routed directly into memory for specific predetermined times dwell time and stored in sequential memory locations To use this mode first acquire a spectrum using the Pulse Height Analysis mode While acquiring the spectrum adjust the LLD and the ULD to select the energy range of interest for example selecting only the 662 keV peak from CS 137 will eliminate unwanted background and produce a superior decay curve when using a Cs 137 Ba 137 mini generator Click the Mode menu and select MCS trum Techniques UCS30 Spectrum Techniques UCS 30 11 Click the Settings menu and select MCS Vl ucsao SN 1018 MCS Internal version 1 1 07 USB File Spectrum Mode Display Settings Strip Background Oo x A ROI 7 Voltage DES Energy Calibration Ki Time mes Integral Count High Voltage Amp ADC S Settings Mossbauer Settings Select Device gt Restore Default Settings The Setup MCS Dwell Time dialog box will appear Dwell Time Wm a Num Enter the Dwell Time This time is for each memory location channel Remember the total pass time will be eq
65. Expander HeNe x10 Beam Expander Adj Focus 2mm input 31 2520 000 Beam Expander HeNe x5 Beam Expander Adj Focus 4mm input Kontakt Holger Rebscher Tel 49 0 6071 968 303 e mail Holger Rebscher coherent com Petra Kreim Tel 49 0 6071 968 302 e mail Petra Kreim coherent com Coherent Deutschland GmbH Laserzubeh r Dieselstrafie 5b 64807 Dieburg Fax 49 0 6071 968 499 4of4 www coherent de Phillips Octal Scientific Discriminator FEATURES INDIVIDUAL THRESHOLD AND WIDTH CONTROLS LINEAR SUMMED OUTPUT BOTH FAST VETO AND BIN GATE LOW COST EIGHT 8 CHANNELS IN A SINGLE WIDTH NIM MODULE DESCRIPTION The Model 705 was specifically designed for modern experiments with large counter arrays offering high per formance and reliability at a reasonable cost The 705 features eight 8 totally independent channels with in dividual threshold and width controls In addition a fast veto input and a summed output are common to all channels Each channel has a threshold adjustment continuously variable from 10 mV to 1 Volt with a front panel test point providing a DC voltage ten 10 times the actual threshold setting Likewise each channel has a non updating regeneration circuit for adjustable output widths from 6 nSEC to 150 nSEC A unique summed output is common to all eight chan nels providing 1 mA of current for each activated channel thus allowing a fast decision to be made on the n
66. G LEgeGE0t64t H3 1SVINOW OHL Z 01 HLON3T1SW3QTIDOHS 811 H3qnoHs NVId HL 1108 H3Q7n00HS ONISN SH3QI TS OL FIGNVH 3 18 N3SSV 2 dOHS 3NIHOVIN Ad CalIddNS SL 108 HAC TINOHS ANY SHSCITS SSVH8 L SALON G3AOtdddV 31vq NOILdlW OS3qd A3H 3NOZ SNOISIA3H KOZ t dO L EL 133HS END g I SLOS 1S VELLE g I INSGNLS H3d v3L Au ON 9MA ON WOS4 3ZIS Am LCEP LLE GOS 1909 IN T1V HIZ8 WN 2nbionbugpy ALV1d ASVd WIHALV AN DA stzuro 6161 doys ounjovjy KurOUOIISV 2 SST Jo 1u ur11ed q day03HO 7 r AAS MNVHO QNVH 4301S OML SL S L 3NOVAVHO V OXT n Siva NH Jo ALIS AIN A i a20 005 SO1d Z OSE Y BEEN SH3NHOO dHVHS NV S390 TIV vada Q3 LLON SS3 INA S00 SNOISNAWIG TIV S3HONI NI SNOISN3NIQ TIV L SALON ra c 0 FOSZ E 000 28 X LES BA lt 0001 nuHL 4 LSZ xz GIN La l 88 000 L I Y E OSZ SO1d Z 91 6 eet i 000 L GIE Y S3 1OH DNILNNOW ANNS AAV SL G L H31N3O WOH SWIG SAO NO 3ONVH3TIOL GHDNVHO 8 d3 AOHddV alva NOlLdlHOS3d AH 3NOZ r 0001 e SNOISIA3H vrdOc EL l33HS 31v9S g SLOS 1S Se d I 1N3QNLS Had val Aad ON SMG ON IN9Sd ER ALO LEEF
67. G may result in severe instrument damage INPUT BNC connector This input is for signals from a scintillation detector scintillation preamplifier or other type detector amplifiers proportional counter germanium detector for eventual processing by the ADC The internal scintillation preamplifier and also the scintillation amplifier can be bypassed using the Mode menu MCS IN BNC connector to input positive Multichannel Scaling MCS TTL pulses gt 150nsec 5 MHz maximum rate ROI OUT OPTIONAL BNC connector supplies a pulse output when data is acquired in a channel marked as a Region of Interest ROI The pulse width is adjustable from 100 usec to 25 msec by an internal pot The pulse amplitude is adjustable from 0 volt to 7 5 volts by an internal pot GATE IN BNC connector for connection to external coincidence unit A positive TTL pulse causes the ADC to accept the next pulse The Gate pulse must be present before the peak of the input Pulse Gate pulse width 50 nsec to 2 usec MSB OUT BNC connector to output the most significant MCS bit for Mossbauer Applications The output pulse period in seconds is equal to the dwell time multiplied by the conversion gain Used as a trigger for an external device i e constant acceleration drive Output will begin after the first pass in Mossbauer mode T COMP Modular connector for connection to temperature compensated tube base USB Universal Serial Bus connector for communicati
68. GES INSIDE SERVICE BY AUTHORIZED PERSONNEL ONLY MSB ROI GATE MCS OUT OUT IN N OO Spectrum Techniques UCS 30 MADE IN USA T COMP NPUT D O 52 Software System Display Time Mode ROIs Integral Energy Cal Temp Comp Strip Smooth Control File Print ROI File IsoMatch Operates under Windows 2000 Windows XP with 600 kb disk space for the executable file and 6 meg for the optional help file available disk space 64 MB RAM 128 MB recommended and compatible mouse VGA or SVGA color graphics 800x600 recommended Linear vertical scale adjusts from 64 to 16M and full range logrithmic display Horizontal 4096 channels with reduction down to 128 channels Preset live time or preset real time selection Both times are recorded and displayed Multiple Regions of Interest using color coding When cursor is in ROI computes gross area net area with end point averaging centroid and FWHM 2 point linear or 3 point quadratic converts cursor position reading directly to energy units Time units in MCS mode Temperature compensation adjusts high voltage to compensate for fluxuations in temperature when using a suitable PMT base Subtracts channel by channel time normalized data stored in File Mode Overlays two saved spectra in File Mode 3 point smoothing of selected displayed data Software control of High Voltage Amplifier Gain Lower and Upper level discrimin
69. IT ca ca Iso Match Library NOT loaded Iso Match Library IS loaded The dialog box top window labeled Select an existing isotope will be empty unless an Iso Match library has been loaded If a library has been loaded you can select on of the entries from the window if a library has not been loaded or you want to add an entry to the list enter the name in the second window titled or enter and isotope name Enter the number of peaks you want to add for this isotope in the third box labeled Enter number of peaks 10 max and click on Edit Further dialog boxes will appear that allow you to enter peak s for the isotope fsotopecdt Isotope Half Life Cs 1 37 30 years Peak Energy KeV Abundance Add Delete Edit If you want to save the Iso Match to a disk file open the File Menu and click on Save Library Spectrum Techniques UCS 30 37 Edit Smooth Data Edit Smooth Data allows the user to apply a three point smoothing algorithm to the displayed data Mode Display Display Peak Repor Data Report v Calibration v ROls Iso Match Pixel Size Display Peak Report If regions of interest have been set around peaks in a spectrum the Peak Report provides a convenient method of displaying peak information in tabular form Readout will be in energy units if the energy calibration is active Display Data Report The Data Report includes all hardware setting counting paramete
70. In the ASYMMETRIC WINDOW mode the upper level dial becomes a window width control with a 0 to 1 V range The lower level dial controls the lower limit of the window over a 20 mV to 10 V range Pulse amplitudes between the upper and lower limits of the window produce an SCA output This mode is useful when a narrow range of pulse heights must be selected In the SYMMETRIC WINDOW mode the upper level dial still controls the window width over the range of 0 to 1 V but the lower level dial sets the position of the center of the window over a range of 20 mV to 10 V The SYMMETRIC WINDOW mode is useful when the window has been centered on a peak in the spectrum and it is desirable to widen or narrow the window to accept more or less of the peak width Rear panel connectors provide separate outputs for the upper and lower level discriminators These logic outputs are generated at the instant the input signal exceeds the corresponding discriminator level The SCA output logic pulse is generated when the input signal falls through the lower level threshold An external input for the lower level setting is switch selectable to allow recording the entire pulse height spectrum utilizing a scanning technique A narrow window is selected and an external voltage source is employed to slowly scan the lower level through the 0 to 10 V range A ratemeter counts the SCA output and draws the spectrum on a strip chart recorder
71. LLE GOS 1909 WI HIZ8 WN 2nbionbugpy SLA WHY 3 TIONVH IVigHalviN AN DA SPOT 6161 doys ounjovjy KuroUOIISV 2 sors nq Jo 1u ur1ed q Q3393H9 EE r AS XNVHO QNVH H3qI1S OML sus anovayuoy QXLXAW MAN fo A LISUAAINN AHI 31iva NMVuG SH3NHOO dHVHS ANY s3903 1Y yvatu8g E G3LON SS3 INf S00 SNOISNAWIG TIV 2 S3HONI NI SNOISN3INIG TIV L SALON 02r V V uonoes ULLA LA E LWA 087 Gen 0SZ SE 00S yo f V V 08 Dr 4 NYHLWVAY GEO NYHL 0S2 xz 000 SL S L S OL 9HO 31OH QN3 H3QIM H3ONOTINHV 8 qaAouddav 31va NOLLdIHOS3G A3H 3NOZ SNOISIA3H dO LS 133HS EG SLOS 1S q I IN3GNLS H3d Val Aad ON DAC ON WOS4 3ZIS ALO ssvug LAN SSVH8 9 SONJ SSvHug SVpist ZCEF ZZC 60 IIIZ8 WN anbionbnqyy AN Du SPOT 6161 4NVHO GNVH H3Ql 1 OML QqaxoaHo doys ounjovjy KKurouo11sy X sors qq Jo 3u2urj1edaoqz SL S L aiva J3NOVAVHO V NMYHG OOIXAW MAN foXLISUAAINN AHJ SYANHOO dHVHS ANY S3904 TIV MVS Q31ON SS3 Nf S00 SWIG TIV lt SAHONI NI SNOISNAWIG TIV L S3LON LAN INVP X3H 91 8 dO LNIdd 35IVIN LSNW SLNAGNLS qaAOHddv 3iva NOI LdlHO9S3dqd A3H 3NOZ SNOISIA3H 09 Ve ONN 91 8 GHL NO NOILVINHOHNI dN HOOT LSfIIN SLNAGNLS 0S7 Gelb 00S
72. M Counts 5 et Centroid Click Overlay Spectra to view the spectrum and the background at the same time Strip Background from Spectrum Strip Background View Hep Load Spectrum Load Background Show spectrum Show Background Overlay Spectrum and Background Strip Background from Spectrum Click Strip Background from Spectrum to subtract the two spectra where the background is corrected for the difference in the data collection time to give a correct proportion As an example if the background count time is 10 minutes and the sample count time is 60 minutes then the Strip Background from Spectrum function will subtract 1 6 10 minutes background count time 60 minutes sample count time of the background counts from the sample spectrum Spectrum Techniques UCS 30 47 View View Toolbar Status Bar Allows the user to display or not display the Tool Bar and or the Status Bar Tool Bar Allows the user to display or not display the Tool Bar Status Bar Allows the user to display or not display the Status Bar Help The Help menu provides a convenient operator reference for the UCS 30 in the standard Windows Help format Contents The Help menu provides a convenient operator reference for the UCS 30 in the standard Windows Help format Using Help The Using Help item provides the standard Windows Help on using the Windows Help system Spectrum Techniques UCS 30 48 ms lt rIIrIIs About
73. Note This laboratory can only be taken after the student has completed Lab I Purpose Familiarize the student with all aspects involved in the development of an experiment Reading Assignment As needed Building Scientific Apparatus 3rd edition by John Moore Christopher Davis and Michael Coplan Perseus Books Cambridge MA 2003 Other material as necessary for the particular experiment being developed Introduction An experimental scientist will develop scientific apparatus in order to conduct experimental studies Even those planning on going into theoretical studies will find exposure to the development of scientific apparatus helpful because they will often interact collaboratively with experimental scientists Procedure The students will work with the assistance of the instructor and TA on the development of a new experiment for Senior Lab The instructor will define the goal of the experiment and its basic arrangement During their four week laboratory exercise the students will develop apparatus needed for the experiment A given student group will have reasonable freedom in their activities that will involve 1 Designing experimental apparatus 2 Procuring the hardware software needed to construct the apparatus 3 Constructing the apparatus and lastly 4 Testing the apparatus and iterating on its design so as to achieve the measurements required Four weeks is not enough time to complete the development of an entire experim
74. OINC and ANTICOINC select ANTICOINC GATE should be OPEN The SCA is not important for this experiment Leave the ULD at 10 and the LLD at 0 Buttons or switches associated with the SCA should be set to OFF or OUT Anything that says DELAY is not important This adjusts the time between the accepted STOP signal and the TAC output pulse For slow count rates 10 us is nothing to worry about 2 13 APPENDIX 2 Gamma Ray Spectroscopy EG amp G ORTEC Wednesday December 11 2002 ORTEC AN34 Experiments in Nuclear Science Laboratory Manual Page 1 HOME SEARCH NEW ORDER ONLINE PRODUCTS APPLICATIONS CONTACT US ORTEC AN34 Application Note Experiments in Nuclear Science AN34 Laboratory Manual Third Edition Revised Introduction to Theory and Basic Applications Alpha Beta Gamma X Ray and Neutron Detectors and Associated Electronics Published September 1987 http www ortec online com application notes an34 an34 front htm EXPERIMENT 3 Gamma Ray Spectroscopy Using Nal TI EQUIPMENT NEEDED FROM EG amp G ORTEC FOR EXPERIMENTS 3 1 THROUGH 93 7 3 9 and 3 10 Bin and Power Supply 905 3 Nal T Crystal and Phototube Assembly 266 Photomultiplier Tube Base 556 High Voltage Power Supply 113 Scintillation Preamplifier 575A Amplifier Os gamma source 5 Ci 5 SK 1G Source Kit see Appendix Absorber Kit Model 3 Z2 Absorber Kit PbAI 23 M Nal 3 Stand for Sodium lodide Detector ACE 2K MCA System including suit
75. PHYS 493L Call 28340 Monday and Wednesday 1400 1650 hr Room P amp A 116 Instructor Paul R Schwoebel Physics and Astronomy Building Room 122 Phone 277 2616 E mail kas unm edu Office hours By appointment Text optional Building Scientific Apparatus 3rd edition by John Moore et al Cambridge University Press 4 ed 2009 Some reading in this book will be required Other reading material will be recommended as it pertains to a particular lab element Purpose Senior Lab will expose students to the diverse experimental techniques required of a graduate student or professional scientist These techniques will be developed with the hands on experience gained through a series of experiments that each require multiple class sessions These experiments will involve holography elementary particle decay Doppler shifts interference phenomena and gas discharges The student will be exposed to a variety of important techniques including interferometry precision timing and coincidence techniques particle detection and sensitive velocity measurements The laboratory will also include an element devoted to elementary aspects of machine shop practice and an element in which the student participates in the development of a new experiment that will be come a permanent addition to the Senior Lab Grading Grades will be based on your performance in the laboratory such as thorough complete laboratory notebooks experimental analysis and laborat
76. SPECTECH Quick Start Guide April 2008 IMPORTANT NOTE Software for this spectrometer should be installed before it is connected and powered on If you have already connected the UCS 30 to your computer do not power on until software instal lation is complete Spectrum Techniques LLC Oak Ridge Tennessee USA INTRODUCTION The purpose of this guide is to provide you with assistance to quickly install setup and begin using your UCS 30 Universal Computer Spectrometer USB INSTALL SOFTWARE Install the software CD shipped with your UCS 30 system into your CD ROM drive The auto start feature will open the InstallShield Wizard Click Next to continue CG UCS30 InstallShield Wizard Welcome to the InstallShield Wizard for UCS30 The InstallShield R Wizard will install UCS30 on your computer To continue click Next Verify your user information and the default destination folder C Program Files Spectrum Tech niques UCS30 You might want to note this Program installation path in case you want to store spectra in this loca tion Ready to Install the Program The wizard is ready to begin installation If you want to review or change any of your installation settings click Back Click Cancel to exit the wizard Installshield UCS 30 Quick Start Guide 2 Click Install to begin program installation if you are satisfied with your entries The installation will begin You c
77. Specifications PERFORMANCE DYNAMIC RANGE 500 1 PULSE PAIR RESOLVING TIME 100 ns plus output pulse width THRESHOLD TEMPERATURE SENSITIVITY lt 0 01 of full scale per C from 0 to 50 C using a NIM Class A power supply referenced to 12 V WINDOW WIDTH CONSTANCY Variation lt 0 1 of full scale window width over the 20 mV to 10 V linear input range DISCRIMINATOR NONLINEARITY lt 0 25 of full scale for both discriminators INDICATORS SCA OUT LED Front panel LED flashes whenever an SCA output pulse is generated CONTROLS WINDOW OR UPPER LEVEL Front panel 10 turn locking dial determines the window width 0 to 1 V in the WINDOW modes or the upper level threshold 0 to 10 V in the NORMAL and INTEGRAL modes LOWER LEVEL Front panel 10 turn locking dial determines the threshold setting 20 mV to 10 V for the lower level discriminator when the rear panel LL REF switch is in the INT position The LOWER LEVEL control is disabled when the EXT position is selected on the rear panel LL REF switch INT ASYM WINDOW SYM WINDOW NORM Front panel four position rotary switch selects one of four operating modes INT In the INTEGRAL mode the lower level and upper level are independently adjustable from 20 mV to 10 V The SCA OUT is generated for all pulse amplitudes exceeding the lower level threshold NORM In the NORMAL mode the lower level and upper level are independently adjustable from 20 mV t
78. a convenient method of removing naturally occurring background from a sample spectrum and can be very useful when working with low level environmental samples Load Spectrum Strip Background View Help Load Spectrum Load Background Click on Load Spectrum and in the File Dialog Box that opens select the spectrum you intend to have the background stripped from For example the spectrum may be taken for an isotope the background may be the readings with no isotope present Spectrum Techniques UCS 30 Load Background Strip Background View Help Load Spectrum Load Background Click on Load background and in the File Dialog Box that opens select the background you intend to strip from the first For example the spectrum may be taken for an isotope the background may be readings with no isotope present Show Spectrum Strp Background View Help Load Spectrum Load Background v Show spectrum Show Background Strp Background from Spectrum Click Show Spectrum to view spectrum Show Background Strip Background View Hep Load Spectrum Load Background Show spectrum v Show Background Overlay Spectrum and Background Strip Background from Spectrum Click Show Background to view background 46 Overlay Spectra A Spectrum Techniques UCS20 File Mode TEST1 spu File Edit Mode Display Settings Stip Background View Help Jedi NH mE m c SP ERD Channel 511 Energy Gross FVVH
79. able IBM PC other EG amp G ORTEC MCAs may be used Oscilloscope ADDITIONAL EQUIPMENT NEEDED FROM EG amp G ORTEC FOR EXPERIMENT 3 8 427A Delay Amplifier 551 Timing Single Channel Analyzer 426 Linear Gate 875 Counter gd Purpose The purpose of this experiment is to acquaint the student with some of the basic techniques used for measuring gamma rays It is based on the use of a sodium iodide Nal detector that is thallium TI activated Gamma Emission Most isotopes that are used for gamma measurements also have betas in their decay schemes The typical decay scheme for the isotope will include a beta decay to a partic ular level followed by gamma emission to the ground state of the final isotope The beta particles will usually be ab sorbed in the surrounding material and not enter the scintil lator at all This absorption is normally assured with alumi num absorbers ref 10 For this experiment the betas offer no real problem and so absorbers are not specified There will be some beta absorption by the light shield over the phototube The gammas however are quite penetrating and will pass easily through the aluminum light shield Generally there are two unknowns that we would like to investigate about a gamma source One is the energies of the gammas from the source the other is the number of gammas 905 3 Mai SCINTILLATOR AND PHOTOTUBE SOURCE 266 PM BASE 556 HV POWER SUPPLY Fig
80. ak amplitude when the entire photocathode is illuminated by a delta function light pulse J The electron transit time is the interval between the arrival of delta function light pulse at the entrance window of the tube and the time when the anode output reaches the peak amplitube In measurement the whole pho tocathode is illuminated K Also called transit time jitter This is the fluctuation in electron transit time between individual pulses in the signal photoelectron mode and may be defined as the FWHM of the frequency distribution of electron transit times L Hysteresis is temporary instability in anode current after light and voltage are applied Imax lmin Hysteresis X 100 ANODE CURRENT i L I A W WE WE Lx d 3 vd i a R TIME 7 minutes TPMSB0002EA 1 Current Hysteresis The tube is operated at 750 volts with an anode current of 1 micro ampere for 5 minutes The light is then removed from the tube for a minute The tube is then re illuminated by the previous light level for a minute to measure the variation 2 Voltage Hysteresis The tube is operated at 300 volts with an anode current of 0 1 micro ampere for 5 minutes The light is then removed from the tube and the supply voltage is quickly increased to 800 volts After a minute the supply voltage is then reduced to the previous value and the tube is re illuminated for a minute to measure the variation Table 1 Voltag
81. al Real time data is displayed on an updating histogram The distribution should approach an ideal Gaussian depending on the number of data points and histogram bins When sufficient data has been collected stop the program Repeat the measurement but stop it when the number of data points is about half of the first run Change the decay detector to the other PMT and do the same pair of measurements 4 total For the analysis produce a histogram with a Gaussian fit for all the data sets to determine the mean pulse width and variance express the latter as a percentage of the mean How does the analysis depend on the number of histogram bins Comment on the differences and calculate the experimental uncertainty for each data set Muon decay Select the measurement Decay and open the Coincidence tab In this experiment the decay detector waits for a second photon that follows the coincidence trigger which should correspond to a muon decay The program must be configured to ignore trigger events which will radically skew the data toward time zero The gate minimum setting must be set longer than duration of any possible trigger pulse accounting for fluctuations introduced by the coincidence time window Tip The gate minimum should be longer than the gate width used in the preceding experiment To observe the expected exponential decay the gate should remain open for several muon decay lifetimes order of microseconds If the gate width is set lo
82. an monitor the install progress by watching the status bar The in stall should be reasonably quick and will conclude by displaying the InstallShield Wizard Com pleted screen Click Finish to exit the install wizard ig UCS30 InstallShield Wizard K Installing UCS30 The program Features you selected are being installed 4 Please wait while the InstallShield Wizard installs UCS30 This may take several minutes Status Copying new files Beene eee Cee Note the UCS 30 icon that has been installed on your desktop Using your Windows Explorer examine the contents of C Program Files Spectrum Techniques UCS30 This file should contain a Drivers folder an Examples folder and several UCS 30 files including the UCS 30 Manual in Adobe PDF format You may want to create a shortcut to the man ual and place it on your desktop for quick reference Remove the installation CD from the CD ROM drive and store it in a safe place SYSTEM SETUP Connect your detector to the UCS 30 Connect the detector high voltage cable to the MHV connec tor on the UCS 30 labeled POS HIGH VOLTAGE Connect the BNC signal cable from the detector to the BNC connector on the UCS 30 labeled IN PUT NOTE If you are using a detector with a preamplifier included connect to the INPUT BNC connec tor and set the UCS 30 MODE to PHA Amp In If you are using a detector with a preamplifier AND external amplifier connect the detector signal ca ble to t
83. ancel button will result in the temperature compensation calibration process being aborted A Spectrum Techniques UCS30 Live Mode Olm E3 E 16M Spectrum Techniques UCS 30 ad ev FTHM Centroid 28 Displaying Isotope Peaks Isotope peaks may be indicated on calibrated spectra These peaks are selected from a list provided by selecting the Display menu and clicking on Iso Match The following dialog box will be displayed show Isotopes E Display Isotope Half Life Peak Report Co 60 Data Report be v Calibration al 10 4 years v BOls 54 312 2 days Iso Match sae 244 1 days Pixel Size Cancel Click the isotopes peaks in the window that you want to display These will be highlighted to indicate selection When your list is complete click Okay to display them Editing the Iso Match list Select the Edit menu and click Iso Match The following dialog box will be displayed Edit Experiment lso Match Smooth Data Spectrum Techniques UCS 30 Isotope Match Edit JES Isotope Match Edit Bi sd Isotope Half Life Isotope Half Life 5 27 years Cd 109 1 27 years Cs 137 30 years Ba 133 10 4 years Mn 54 312 2 days Na 22 14 65 years Zn 65 244 1 days Add Delete EDIT Add Delete EDIT Aa _osee eo Des em ca ca IsoMatch Library NOT loaded IsoMatch Library IS loaded The dialog box top window labeled Select an existing isotope will be empty unless
84. ate the data using three points Settings Energy Auto Calibrate Clicking Auto Calibrate initiates a calibration sequence During Auto Calibration high voltage and gain settings are automatically adjusted in sequence to determine optimum settings for energy calibration assuming detection of Cs 137 source Once started the operator is given an opportunity to cancel A cancelled autocalibration does not revert to prior settings Spectrum Techniques UCS 30 4 Lem AutoCalibration in Progress SN 00120 Autocalibration will take a few minutes to complete Please stand by This message will close when process is complete If you wish to abort the operation early press the Cancel button Cancel Settings Preset Clicking Presets allows the user to select the Presets Dialog box Settings Amp HV ADC Clicking Amp HV ADC allows the user to select the Amp HV ADC Dialog box Settings MCS Clicking MCS allows the user to access the MCS Dwell Time dialog box if the Mode is set to MCS Dwell Time 100 ms zd Scroll to the desired Dwell Time then highlight the value selected then press OK Spectrum Techniques UCS 30 42 LEE Settines Color Clicking Color allows the user to select the Colors Dialog Box to set or change the colors for the ROIs and Background The Color Dialog Box allows the user to select custom colors for ROIs Plot Background Plot Border and Text Select the item to change click on Change select th
85. ators and ADC Conversion Gain Save or load data file and header information in binary or spreadsheet compatible formats Prints current screen display to Windows printer Saves ROI data centroid FWHM gross and net integrals and header information in spreadsheet compatible format Isotope library text file with peak markers and labeling for overlaying on spectrum for quick isotope identification Library may be edited from Edit IsoMatch pull down menu Spectrum Techniques Contact SPECTRUM TECHNIQUES LLC 106 Union Valley Road Oak Ridge TN 37830 USA Tel 865 482 9937 Fax 865 483 0473 e mail sales SpectrumTechniques com Web Site http www SpectrumTechniques com Spectrum Techniques UCS 30 53 A Sees The EG amp G ORTEC Model 567 Time to Amplitude Converter Single Channel Analyzer TAC SCA meas ures the time interval between start and stop input pulses generates an analog output pulse proportional to the measured time and provides built in single channel analysis of the analog signal Additional gating mod ules are not necessary with this unit and timing experiments requiring time ranges of 10 ns to 2 ms may be performed with single channel analy sis giving the experimenter unparal leled flexibility in analyzing random nuclear events that occur within a selected time range Time ranges from 50 ns to 2 ms are provided via the front panel controls Separate gating anticoincidence or u co
86. ble with many scintillation detectors and commercial tube bases Amplifier On board combination preamplifier amplifier for use with scintillation detectors and PMTs Computer controlled coarse and fine gain from x1 to x160 ADC Wilkinson type with 80 MHz clock and computer selected conversion gain of 4096 2048 1024 512 or 256 channels Direct input accepts pulse peaking times of 1 usec to 10 usec Includes dead time correction when used in Live time mode LLD amp ULD Lower Level and Upper Level discriminators Independently computer controlled in 4 channel increments over entire input range Operates prior to ADC for reduced system dead time Modes MCA for pulse height analysis or MCS for half life decay or other time related studies Timers Real time or Live time operation selectable in 1 second increments for PHA or dwell times from 10 msec to 600 seconds per channel in MCS mode Data Memory On board static RAM 4096 channel x 3 Bytes for data plus region of interest flag Deadtime System dead time is computed and displayed on screen during acquisition Power AC line powered with an auto sensing power supply for 100 250 VAC 10 watts total Connections On Rear Panel Rear Panel WARNING PREAMP POWER FOS NEG DANGEROUS VOLTAGES MANUF ACTURED BY SPEC TRUM TECHNIQUES OAK RIDGE TENNESSEE 37830 O O ON HV CONNECTORS HIGH VOLTAGE AC POWER IN 90 240 VAC 50 60HZ WARNING DANGEROUS VOLTA
87. by 5 nSEC 5 nSEC minimum input width Bin Gate Rear panel slide switch enables or disables slow bin gate in accordance with TID 20893 GENERAL PERFORMANCE Continuous Repetition Rate OUTPUT CHARACTERISTIC General Three LEMO connector outputs per channel One negative bridged pair and one comple mentary output The bridged outputs deliver 32mA into a single 50 ohm load 1 6 volts or l mA 800mV when both outputs 50 ohm terminated The complement is quiescently l6mA BO0mV and goes to OmA during output The output rise and fall times are less than 1 5 nSEC from 1096 to 9096 levels Width Control One controi per channel 15 turn screwdriver adjustment outputs continuously variable from 6 nSEC to 150 nSEC non updating x 296 C stability Summed Output One LEMO connector output common to all eight B channels 1 mA output pulse 50 mV into 50 ohms for each channel fired Output duration is equal to the out put width setting of the respective channel Output rise and fall times less than 2 5 nSEC into 50 ohms Up to 16 channels can be direct ly OR D by cable Greater than 75 MHz with output width set at minimum Pulse Pair Resolution Better than 12 nSEC with output width set at minimum Input to Output Delay Less than 9 nSEC Multiple Pulsing One and only one output pulse regardless of input pulse amplitude or duration Power Supply Requirements 6 Volts 420
88. c tor lead shield arrangement Backscattered gammas from these interactions Ej make photoelectric interactions in the Nal TI when they enter the crystal The energy of the backscattered peak can be found by solving Eq 2 Solve Eq 2 for the background gammas from Cs and for the 1 33 MeV gammas from Co Fill in the rest of Table 3 1 How do your measured energies compare with the theoreti cal energies from Eq 2 If the backscatter peak is not very pronounced in your spectrum it can be improved by accu mulating a spectrum with a sheet of lead absorber placed slightly to the left of the source in Fig 3 1 EXPERIMENT 3 4 Energy Resolution Purpose The resolution of a spectrometer is a measure of its ability to resolve two peaks that are fairly close together in energy Figure 3 2 shows the gamma spectrum that was plotted for the Cs source The resolution of the photopeak is found by solving the following equation E y 100 5 E where R the resolution in percent E the full width of the peak at half of the maximum count level FWHM measured in number of channels E the channel number at the centroid of the photo peak In Fig 3 2 the photopeak is in channel 280 and its FWHM 32 channels From Eq 5 the resolution is calculated to be 11 5 EXERCISE Calculate the resolution of the system from your Cs spec trum Record this value for later reference EXPERIMENT 3 5 Activity of a
89. controlling the lower level threshold when the INT EXT LL REF switch is in the EXT position The input range of 20 mV to 10 V corresponds to a lower level threshold range of 20 mV to 10 V The input is overload protected to 15 V OUTPUTS SCA OUT Front and rear panel BNC connectors provide a NIM standard positive logic pulse output nominally 5 V amplitude and 500 ns width Output impedance 15 Q Front and rear panel outputs have separate www ortec online com Tel 865 482 4411 e Fax 865 483 0396 ortec info G ametek com 801 South Illinois Ave Oak Ridge TN 37831 0895 U S A For International Office Locations Visit Our Website 550A Single Channel Analyzer output drivers The output pulse occurs when the trailing edge of the linear input pulse crosses the lower level threshold See description under CONTROLS for output logic modes Front panel test point wired to the SCA OUT connector through a 470 Q resistor LL OUT Rear panel BNC connector provides a NIM standard positive logic pulse output nominally 5 V amplitude and 500 ns width Output impedance 15 Q The output pulse occurs when the leading edge of the linear input pulse crosses the lower level threshold INT or NORMAL modes or the lower limit of the window WINDOW modes UL OUT Rear panel BNC connector provides a NIM standard positive logic pulse output nominally 5 V amplitude and 500 ns width Output impedance 15 Q The output puls
90. d of light to determine the wavelength in vacuum one can calculate the distance d from the equation for A above This is in fact how the meter is currently defined through the definition of c and the second This technique will then require two lasers the frequency of one of them is well known The fringe count of the known laser frequency is used to calculate the distance d which is in turn used knowing the fringe count for the other laser to calculate the unknown 6 2 wavelength Several arrangements are possible One of them is the Mach Zehnder interferometer The other is the double Michelson sketched in Fig 2 One should be aware that this method provides a wavelength ratio in the laboratory environment Depending on how successful your experiment is you may have to correct for the dispersion of air The appropriate constants for that correction can be found in the Handbook of Chemistry and Physics Chemical Rubber Co Two other limitations are the bandwidth and stability of the reference laser as well as that of the laser to be measured These bandwidth and stability are two different factors which might but need not be related Experimental Setup Attempt to make a Michelson interferometer using an air rail as one arm see Fig 2 This interferometer will be used as a wavemeter by combining two lasers a known reference red He Ne and an unknown source green He Ne this is the least you should determine The polari
91. de with the thin alumi num foils calculate and average u Eq 9 Repeat for the other absorbers b Make a plot of u vs Z E from your experimental data How do your results compare to the theory References 1 G F Knoll Radiation Detection and Measurement John Wiley and Sons New York 1979 2 J B Birks The Theory and Practice of Scintillation Counting Pergammon Press Oxford 1964 3 S M Shafroth Ed Scintillation Spectroscopy of Gamma Radia tion Gordon and Breach London 1967 4 K Siegbahn Ed Alpha Beta and Gamma Spectroscopy North Holland Publishing Co Amsterdam 1968 5 P Quittner Gamma Ray Spectroscopy Halsted Press New York 1972 6 W Mann and S Garfinkel Radioactivity and its Measurement Van Nostrand Reinhold New York 1966 7 C M Lederer and V S Shirley Eds Table of isotopes 7th Edition John Wiley and Sons Inc New York 1978 8 Radiological Health Handbook U S Dept of Health Education and Welfare PHS Publ 2016 Available from National Technical Information Service U S Dept of Commerce Springfield Virginia 9 14th Scintillation and Semiconductor Counter Symposium IEEE Trans Nucl Sci NS 22 1 1975 10 R L Heath Scintillation Spectrometry Gamma Ray Spectrum Catalog 1 and 2 Report No IDO 16880 Available from the National Technical Information Center U S Dept of Commerce Springfield Virginia APPENDIX 3 MANUALS
92. deg 914 none 0221 15 00 Sys LG3 30Deg 670nm 2 5mW VLM3 Line Generator 670nm 2 5mW 30 Degree Fan Angle 9 5 mm 25 1 p 914 none 0222 037 00 Sys LG3 3 40Deg 635nm 1 5mW VLM3 Line Generator 635nm 1 5mW 40 Degree Fan Angle 9 5 mm 15 1 pos 914 none 0220 936 00 Sys Indust LG 60Deg 635nm 2mW Industrial Line Generator 635nm 2mW 60 Degree Fan Angle Bright Line 9 5 mm 2 1 ps 304 none 0220 934 00 Sys LG2 3 60Deg 635nm 2mW VLM2 Line Generator 635nm 2 5mW 60 Degree Fan Angle 14 7 mm dia 25 1 ie 914 none 0220 972 00 Sys LG2 3 60Deg 635nm 2mW VLM2 Line Generator 635nm 1 8mW 60 Degree Fan Angle 14 7 mm dia 18 1 Kee 914 none 0221 144 00 Sys LG2 60Deg 670nm 4mW VLM2 Line Generator 670nm 4 2mW 60 Degree Fan Angle 14 7 mm dia 42 1 e 914 none mrad x AMP 0222 603 00 Sys LG3 3 60Deg 635nm 1mW Spc VLM3 Line Generator 635nm 0 8mW 60 Degree Fan Angle Connector AMP 87175 6 9 5 mm 0 95 1 60deg 1000 Lesuzss 0222 206 00 Sys LG3 60Deg 670nm 1 8mW VLM3 Line Generator 670nm 1 8mW 60 Degree Fan Angle 9 5 mm 18 1 pen 914 none 0221 154 00 Sys LG3 60Deg 670nm 3 5mW VLM3 Line Generator 670nm 3 5mW 60 Degree Fan Angle 9 5 mm 35 1 Le 914 none EE Sys FLG3 B0Deg 650nm 1mW Adj VLM3 Line Generator 650nm 1 1mW 80deg Fan Angle Adjustable Focus Line Width custom 5mn m 1 80deg x spedi connector loose label Adjustable mrad x Phono 31 0631 000 Sys Dual X Line 635nm 12mW CW Dual Line Generator Cross Hair 635nm 12mW 19 22 mm dia x142 mm 12 1 85deg 990
93. e occurs when the leading edge of the linear input pulse crosses the upper level threshold INT or NORMAL modes or the upper limit of the window WINDOW modes ELECTRICAL AND MECHANICAL POWER REQUIRED 12 V at 75 mA 12 V at 35 mA WEIGHT Net 0 9 kg 2 0 Ib Shipping 2 3 kg 5 0 Ib DIMENSIONS NIM standard single width module 3 43 X 22 13 cm 1 35 X 4 714 in front panel per DOE ER 0457T Ordering Information To order specify Model 550A Description Single Channel Analyzer Specifications subject to change 011008 AMETEK ADVANCED MEASUREMENT TECHNOLOGY Amplifier Specifications ORTEC 572A http ortec online com electronics amp 572 20spec htm Home Applications Contact Us Search Products Service Training Download PDF 572A Amplifier Order Online Specifications PERFORMANCE A Gain Range Continuously adjustable from 1 to 1500 GAN 05 15 Pulse Shape Semi Gaussian on all ranges with peaking time equal to 2 2x and pulse width at 0 1 level equal to 2 9 times the peaking time Integral Nonlinearity For 2 us shaping time lt 0 05 Noise Typically lt 5 uV for unipolar output referred to the input using 2 us shaping and Coarse Gain 3100 Temperature Instability Gain 0 0075 C 0 to 50 C DC Level 50 uV C 0 to 50 C Bipolar Crossover Walk 3 ns at 0 5 us for 50 1 dynamic range including contribution of an ORTEC Model 552 Single Channel Analyz
94. e Distribution Ratio ec bye by Dy8 Gel P ES Electrode K ou Dy2 Dy3 Dy4 Dy Distribution Ratio AESEREREXER Supply Voltage 1000Vdc K Cathode Dy Dynode P Anode Figure 2 Typical Gain and Anode Dark Current TPMSB0026EA 10 5 108 10 6 107 lt E 10 7 106 i Es 5 8 105 d 10 lt 10 9 104 Ww Q Q 10 10 103 lt 10 11 102 10 12 101 300 400 500 600 800 1000 1500 SUPPLY VOLTAGE V Figure 4 Typical ENI vs Wavelength TPMSBO0027EA 10 12 10 18 10 14 10 15 EQUIVALENT NOISE INPUT W 10 16 10 17 100 200 300 400 500 600 700 800 WAVELENGTH nm Figure 6 Typical Single Photon Height Distribution for R1527P TPMSBO0029EA WAVELENGTH OF INCIDENT LIGHT 450 nm SUPPLY VOLTAGE 880 V LOWER LEVEL DISCRI 71 ch PHOTON DARK COUNT 5562 cps DARK COUNT 10 cps TEMPERATURE 25 C SIGNAL DARK HAMAMATSU Figure 3 Typical Time Response TPMSBO004EB 100 80 60 40 20 TIME ns s 300 500 700 1000 1500 SUPPLY VOLTAGE V Figure 5 Typical EADCI Equivalent Anode Dark Current Input vs Supply Voltage TPMSBO0028EA 10 10
95. e desire color click on OK returns to the Color screen make additional color changes when all color changes have been made click on OK enters data and returns to spectrum screen Color allows the user to select a range of Basic Colors or create Custom Colors Spectrum Techniques UCS 30 43 Basic colors Define Custom Colors gt gt E Dialog Box with standard Colors Basic colors EN ERE WI Custom colors BEB EEE 4 Hue f160 Bech 7 Seck gGemb Deine Custom Colors ColorSalid Lum fo Blue 0 OK Cancel Add to Custom Colors Dialog Box expanded for custom colors Note Setup of computer graphic may affect the true color of the color selected Settings Confirm Spectrum Erasure Unchecking Confirm Spectrum Erasure allows the user to bypass the confirmation of erasing current spectrum data By default this option is checked each time the application is started If Spectrum Techniques UCS 30 44 the setting is unchecked erasure of the current spectrum is immediate and cannot be undone use this feature wisely When the setting is checked a request to erase is followed by the display of a confirmation dialog box to give an opportunity to cancel the request Settings Reset All Variables To Defaults Clicking Reset All Variables To Defaults results in configuration settings being reset to the initialized state A confirmation dialog box will be presented to
96. e satisfied the logic function desired triggering of an updating regenerative stage produces a standard ized output pulse variable from 4 nSEC to 1 uSEC independent of the input pulse shapes or overlap times The updating feature ensures deadtimeless operation while the double pulse resolution is 7 5 nSEC for fast counting applications The outputs are the current source type with two pairs of negative bridged outputs and one complement for each channel When only one output of a bridged pair is used a double amplitude NIM pulse 32 mA is generated for driving long cables with narrow pulse widths The outputs have transition times of typically 1 0 nSEC and their shapes are virtually unaffected by the loading conditions of the other outputs INPUT CHARACTERISTICS A B C D OUTPUT CHARACTERISTICS Four inputs per section LEMO connectors accepts NIM level logic signals 500 mV 50 ohm input impedance direct coupled input reflections are less than 5 for a 1 nSEC rise time inputs are protected against damage from 50 volt input transients Inputs respond to a 1 nSEC or greater input width Five outputs per section two pairs of negative bridged and one complemented NIM The two pairs of bridged outputs are quiescently 0 mA and 32 mA during output 1 6 V into 50 ohms or 8 V into 25 ohms The complemented output is quiescently 16 mA and O mA during output Risetimes and falitimes are less than 1 5 Fast Veto
97. e to follow Output voltages will range from 0 V START FREQUENCY to 10 V STOP FREQUENCY for X and from 0 V lower grid line to 10 64 REFERENCE LEVEL 10 4 V for Y Set the recorder inputs ranges accordingly The outputs are set to the high limits after each plot so zero the recorder at the upper right corner of the page A simple demonstration Watching the radio To demonstrate the operation of the 3585A connect a short piece of unshielded cable to the IMQ input Tune the START and STOP frequencies to locate the AM radio band 0 5 1 6 MHz Position the marker on one of the stations and measure the frequency of the station using the COUNTER Watch the frequency and amplitude of the signal over several measurements Can you see why these are amplitude modulation stations rather than frequency modulation Can you find the FM stations As mentioned in the former subsection the Hewlett Packard 3585A spectrum analyzer may be remotely operated by computer via the IEEE 488 interface also known as the HP IB Hewlett Packard Interface Bus or GPIB General Purpose Interface Bus The program DOPPLER EXE has been written to drive the 3585A and to collect the appropriate data for this experiment Use of this program is the subject of this portion Throughout this section anything that is enclosed in quotes is what you will be expected to type from the keyboard names of special keys which you must type will be enclosed in Dirac brac
98. ed edge triggered and printed wiring board PWB jumper selectable to accept either negative or positive NIM standard signals Input impedance is 50 Q in the negative position and gt 1K in the positive position The threshold is nominally 400 mV in the negative position and 2 V in the positive position STROBE Provides an external means to strobe a valid output signal from the TAC in the Ext Strobe mode The input signal exceeding threshold within the Ext Strobe Reset interval after the Stop input initiates the read cycle for the linear gate to the TAC output Factory set in the positive input position Ext Strobe Reset interval has a minimum value of 0 5 us and a maximum value of nominaily 10 us or 100 ys Switch selectable on rear panel START Time conversion initiated when Start input signal exceeds threshold Factory set in negative input position STOP Time conversion terminated when Stop input signal exceeds threshold Factory set in negative input position RESET INHIB Terminates conversion cycle and maintains reset condition inhibiting further TAC conversions for the duration of the reset cycle or the Reset Inhib pulse whichever is longer A TAC output pulse in process at the time of a Reset Inhib signal will be completed before converter reset is initiated Factory set in the positive input position START GATE Provides an external means of gating the Start circuitry in either Coincidence or Anticoincidence wi
99. eed of the toy train compare with direct measurement The rotation rate of the fast wheel using the interference scattering technique The velocity profile of a laminar flow via the Doppler effect end itemize Food for thought Doppler velocity with the Michelson arrangement It is not really necessary to invoke the Doppler Effect Find an alternate explanation it should lead to the same numerical expression Transverse velocimetry measurement fast wheel This can be interpreted also through the Doppler effect REFERENCES 1 M V Klein and T E Furtak Optics Wiley New York 1986 5 7 APPENDIX HP 3585A Spectrum Analyzer The Hewlett Packard 35854 is a digital spectrum analyzer with a bandwidth of 20 Hz 40 MHz It can be operated manually by the front panel controls or by computer via the IEEE 488 interface The manual method is the subject of this appendix The entry keys of the front panel are divided into eight groups INPUT ENTRY SWEEP TRACE MARKER CONTINUOUS ENTRY RBW VBW ST STATUS and TRIGGER The pertinent keys in each of these groups will be discussed below Most keys are designed so that they will be lit or a corresponding entry on the CRT display highlighted when on or in effect Before discussing the key panel look at the CRT display The horizontal axis is in units of frequency and either the START and STOP frequencies or the CENTER frequency and frequency SPAN will be given below the bottom
100. elease mouse button Clear ROI Move marker to the ROI to be cleared Open the Setting Menu open ROI and select Clear ROI Gross and Net Count When the marker is positioned in a region of interest ROI the UCS 30 software automatically calculates the Gross and Net Functions Energy Calibration Geier GEZ MGSSuauen The energy calibration feature allows the marker to read directly in energy units Two calibration functions are possible a 2 point linear or a 3 point quadratic fit Spectrum Techniques UCS 30 area of the region In order to minimize statistical effects at the ROI endpoints a 3 point averaging technique is applied The contents of channels n n and n 1 are summed and averaged to derive the content of the endpoint channel for the net area computation A linear interpolation is performed between these averaged endpoint values and counts below this interpolation are subtracted to arrive at the Net area of the peak Gross counts is the sum of all channels in the ROI Position the marker in the peak of interest The Gross and Net areas are automatically computed and displayed on the spectrum screen In order to perform an energy calibration it is first necessary to acquire a spectrum using known isotopes Cs 137 together with Co 60 works well for many applications producing gamma lines at 32 keV 662 keV 1173 keV and 1332 keV Select 2 point or 3 point mode and enter the calibrat
101. en be subtracted from the A signal trace 5 MARKER CONTINUOUS ENTRY The MARKER is the highlighted pixel on the spectrum trace which can be positioned by the CONTINUOUS ENTRY knob The frequency and signal amplitude at its position on the trace will be given in the upper right corner of the CRT when it is active When the COUNTER feature is active the trace will stop for approx 0 1 s when the marker frequency is reached and the device will measure the frequency to an accuracy of 0 1 Hz of the strongest signal within one resolution bandwidth RBW see below of the marker frequency The other features in this group are of little interest for our purposes 6 RBW VBW ST The RESolution Bandwidth is the frequency range allowed through the input filters to the system amplifiers it is thus the displayed width of any input signal of bandwidth less than the RBW value displayed at the lower left corner of the CRT It can be reduced to 5 0 resolve closely spaced signal or increased to speed up the sweep rate if the extra resolution is not needed The VIDEO BandWidth VBW bottom center of the CRT is qualitatively speaking the inverse of the time over which a particular element of the display is average as such it can be reduced to average fluctuations in the noise level which might mask weak signals or increased to reduce the SWEEP TIME With the COUPLES TO SPAN feature active the SWEEP TIME ST lower right corner of the display will be auto
102. ent for Senior Lab and thus this will be a group effort over the course of the semester with one group handing off to another group until the experiment is complete The laboratory write up necessary is to be in manual type form describing the apparatus developed and how it is used The write up should provide sufficient information such that someone unfamiliar with the apparatus would be able to operate and repair the apparatus For example the write up should include mechanical drawings and or electrical schematics of the components fabricated photographs of the components a description of their function and an explanation of how they are used in the experiment 3 1 LAB 4 Double Gin Diffraction of Single Photons Birk Reichenbach Rob Cook Devon Hjelm and P R Schwoebel Introduction The end goal of this experiment is to demonstrate as Richard Feynman said the only mystery that is at the heart of quantum mechanics For our purposes that mystery will be defined as If a single particle is incident upon some choice in path and it is impossible to determine which path the particle took then there will be wave like interference between the possible paths But however if there is in principle some way to determine which path was traveled than there will be no interference The single particles here will be individual photons and the choice in path is Young s double slit The issue is the wave particle duality of light which apparently pr
103. er Overload Recovery Recovers to within 2 of rated output from X300 overload in 2 5 nonoverloaded ee widths using maximum gain for Unipolar Output Same recovery from X1000 overload for bipolar Spectrum Broadening Typically lt 16 FWHM for a Co 1 33 MeV gamma line at 85 of full scale for an incoming count rate of 1 to 100 000 counts s Unipolar Output 2 us shaping Spectrum Shift Peak position shifts typically lt 0 024 for a 0Co 1 33 MeV gamma line at 85 of full scale measured from 1 to 100 000 counts s Unipolar Output 2 us shaping ELECTRICAL AND MECHANICAL Power Required 12 V 85 mA 12 V 50 mA 24 V 100 mA 24 V 105 mA Weight Net 1 5 kg 3 3 Ib Shipping 3 1 kg 7 0 Ib Dimensions Standard single width NIM module 3 43 x 22 13 cm 1 35 x 8 714 in per DOE ER 0457T CONTROLS FINE GAIN 10 turn precision potentiometer with graduated dial for continuously variable direct reading gain factor of X0 5 to X1 5 COARSE GAIN 6 position switch selects feedback resistors for gain factors of 20 50 100 200 500 and 1k Jumper on the printed wiring board PWB selects X0 1 attenuation INPUT Locking toggle switch selects either Pos or Neg input pulse 1 of 3 2 15 08 7 50 AM Amplifier Specifications ORTEC 572A http ortec online com electronics amp 572 20spec htm polarity SHAPING TIME 6 position switch selects time constants for active pulse shaping filter network from 0 5 1 2 3 6 and 10 u
104. er Copper and lead are available Plot N X E versus absorber thickness X as you accumulate the data Remember to include the statistical uncertainty in each measurement N in your plot 2 N VN Are your statistics sufficient such that N lt lt N If not accumulate spectra for longer periods of time If spectra are accumulated for different time intervals how do you record them in one plot Have you taken spectra for enough absorber thicknesses to measure the X dependence of N X at small X where N X N 0 and also at large X where N X lt lt N 0 Why is this important Now try the Co source Should your steps in absorber thickness be the same at different y ray energies and or for different absorbing materials Why or why not Do you need to correct for the Nal TI efficiency Why or why not Because you expect an exponential decrease with absorber thickness you should plot your data on a semi log plot Do your results agree with the exponential dependence on absorber thickness Do your results agree with smaller values for u at larger y ray energies If the answer to either of the last two questions is no then you may want to reconsider the geometry of your experimental setup Can the absorber provide a scattering path for y rays not initially directed at the NaI T detector to scatter into the detector How can you minimize this experimental problem Once you have a reliable experimental geometry and analysis procedures
105. er Electrodes 6 100 QUANTUM EFFICIENCY Base 11 pin base JEDEC No B11 88 Weight 45 Suitable Socket E678 11A option Suitable Socket Assembly E717 21 option PHOTOCATHODE RADIANT SENSITIVITY mA W 10 2 100 200 300 400 500 600 700 800 WAVELENGTH nm Information furnished by HAMAMATSU is believed to Ee reliable However no responsibility is assumed for possible inaccuracies or ommissions Specifications are subject to change without notice No patent right are granted to any of the circuits described herein 1994 Hamamatsu Photonics K K PHOTOMULTIPLIER TUBES R1527 R1527P For Photon Counting MAXIMUM RATINGS Absolute Maximum Values Parameter Supply Voltage Between Anode and Cathode 1250 Between Anode and Last Dynode 250 Average Anode Current 0 1 Ambient Temperature 80 to 50 CHARACTERISTICS at 25 C R1527 for General Purpose R1527P for Photon Counting Parameter Min Typ Max Min Typ Max Cathode Sensitivity Quantum Efficiency at 300nm Peak Luminous Radiant at 400nm Peak Bluec Anode Sensitivity Luminous Radiant at 400nm GainE 6 7 X 106 Anode Dark CurrentE After 30minute Storage in the darkness Anode Dark Counts ENI Equivalent Noise Input 3 7X 10 17 0 1 10 Time Response Anode Pulse Rise Time 2 2 Electron Transit Time
106. er Supply HeNe 115 230VAC Green 543 5nm 0 3mW Random m Helium Neon Laser Green 543 4nm 1mW Linear 0 86mm Beam Length 510mm 44 5mm LSR Green HeNe 1mW 20 Linear Diameter uso PSU 31 2439 31 2439 000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC for LSR Green HeNe 2mW 20 Random Helium Neon Laser Green 543 5nm 2mW Random 0 88mm Beam Length 510mm 44 5mm Diameter use PSU 31 2439 31 2439 000 Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC e Mount HeNe 32 51mm 1 4 20 hole pattern adjustable tip tilt Size 190 x 80 OD mm Old 31 1688 000 Mount Hehe Tilt 53 1491 Catalog Part 53 1491 Mount HeNe 44mm 8 32 inch hole pattern adjustable tip tilt 17deg Thumbscrews Size 80 x 20 31 1720 000 Mount Hehe Var US 61 2937 x 88 mm Old Catalog Part 61 2937 4 Mount HeNe 44mm M4 metric hole pattern adjustable tip tilt 17deg Thumbscrews Size 80 x 20 31 1738 000 Mount HeNe Var metric 53 2937 88 mm Old Catalog Part 53 2937 31 1746 000 Mount HeNe Adj 8 32 61 1483 Eeer Hehe 32 51mm 8 32 hole pattern adjustable tip tilt Size 100 x 60 x 61 mm Old Catalog art 61 1483 31 2538 000 Adapter C Ring with screws Adaptor for front of Hehe or Radius System 31 2505 000 Beam Expander HeNe Zoom Beam Expander Zoom 1X to 8X Adj Focus 3mm input 31 2512 000 Beam
107. es to complete Please stand bv This messaqe will close when process is complete If you wish to abort the operation early press the Cancel button Cancel The calibration sequence can require a few minutes to complete In the absence of an adequate source or improper cable connection the process may not succeed Once Auto Calibrate begins an Spectrum Techniques UCS 30 information dialog box is displayed which advises to wait for completion and provides an opportunity to cancel the calibration Pressing of the Cancel button will result in the auto calibration process being aborted and the high voltage setting being reset to zero If allowed to work to completion the gains and voltage will be left at the determined calibration settings and the spectrum scale will be displayed in energy 26 Temperature Compensation UCS30 Live Mode Temperature Compensation THIS FUNCTION IS NOT CURRENTLY AVAILABLE The temperature compensation feature allows the UCS 30 to automatically adjust the fine high voltage to correct for temperature variation In order to perform temperature compensation the fine high voltage factor measured in channels step and temperature coefficient measured in channels degree celsius most be known These can be provided by the use in the Parameters menu or found by allowing the UCS 30 to calibrate for temperature compensation using a cesium source Spectrum Techniques UCS 30
108. esue Adusiabie or VEMS 9 5mm 37 5 x 12 5 x 48 3mm thumbscrews i Mount Laser Diode Module VLM 14 8mm M4 metric hole pattern adjustable tip tit 15deg 1 1621 000 Mount f5mm AN metric S3 1874 Thumbscrews Size 37 5 x 12 5 x 48 3 mm Old Catalog Part 53 1871 5124638500 Mound Snia tass 55 1087 eun Laser Diode E Seck LabLaser 19mm 37 5 x 12 5 x 48 3mm thumbscrew Mount Laser Diode Module Adjustable for VLM3 9 5mm 37 5 x 12 5 x 48 3mm thumbscrews 8 31 1644 000 Mount 9mm AD3 8 32 61 1855 az hole pattern Old Catalog Part 61 1056 Mount Laser Diode Module LabLaser 19mm 8 32 inch hole pattern adjustable tip tilt 15deg SEN Mount 19mm LabLsr US 61 1897 Thumbscrews Size 37 5 x 12 5 x 48 3 mm Old Catalog Part 61 1897 Mount Laser Diode Module VLM 14 8mm 8 32 inch hole pattern adjustable tip tilt 15deg 31 1662 000 Mount 15mm VLM2 US 61 1874 Thumbscrews Size 37 5 x 12 5 x 48 3 mm Old Catalog Part 61 1871 31 1670 000 Mount Base 8 32 M4 53 1913 Mounting Base Universal M4 8 32 68 x 50 8 x 9 5 mm 31 1712 000 Adaptor LabLaser 19mm 53 1962 Adaptor for 19mm LabLaser for Mount 53 1939 Old Catalog Part 53 1962 31 1001 000 Sys LDM Power Supply 5 VDC Power Supply Laser Diode Module Desk Top Mount 5VDC 1 5amp Power Supply LabLaser 6VDC 250ma Adjustable Power Control for MVP lasers Key Switch 5 31 1050 000 Sys LabLaser Power Supply 6VDC Second Delay Emission Indicator Interlock 180 260VAC 120x76x48 mm Phono Plug to
109. fic 13 Ackerman Avenue Suffern New York 10901 USA 914 357 9417 FEATURES MODEL VERSATILE LOGIC MODULE WITH MAJORITY LEVEL SELECTION d FOUR INDEPENDENT CHANNELS ouan ro 125 MHz RATE CAPABILITY PEDES COINC LEVEL e DEADTIMELESS UPDATING OUTPUTS FAST ANTI COINCIDENCE CAPABILITY DESCRIPTION The model 755 logic unit contains four channels of four input logic with veto in a single width NIM module Logic AND OR majority logic fan in fan out and anti coincidence functions can be performed with this versatile module All functions are direct coupled and operate to over 125 MHz with input overlap times as narrow as 1 NSEC Each channel has four logic inputs an anti coincidence input a coincidence level switch and five outputs with common width control The inputs are enabled by connecting the input cable to the desired input eliminating errors often occuring with switched inputs The setting of the coincidence level switch then determines whether a logic OR AND or majority logic function will produce an output After the inputs have satisfied the logic function desired triggering of an updating regenerative stage produces a standard ized output pulse variable from 4 nSEC to 1 uSEC independent of the input pulse shapes or overlap times The updating feature ensures deadtimeless operation while the double pulse resolution is 7 5 nSEC for fast counting applications The outputs are the curre
110. grid line The vertical scale gives the power of the signal in logarithmic units dBm dBV or dB with the power corresponding to the top grid line given by REF the values for the other lines decreasing from this value by the amount given in dB DIV both displayed in the upper left corner Remember that a signal ratio of 10 dB implies an electrical power ratio of 10 while a ratio of 20 dB implies a it voltage ratio of 10 For most optical detectors it is the output voltage that is proportional to the optical power in The RANGE determines the noise level due to the internal amplifiers The upper right corner usually gives the MARKER position but may display other information and will be discussed later The meaning of the entries on the bottom line will likewise be discussed below The CRT is also used to display various messages which will generally be accompanied by a warning tone For example every two minutes or so the instrument will execute a self calibration routine and CALIBRATING will briefly appear on the screen similarly if front panel operation is attempted while the device is in the remote mode the message HP IB OPERATION ONLY will be displayed
111. h Advanced undergraduate and graduate students in the sciences typically have an introductory electronics class lab Often however students are not introduced to the mechanical aspects of designing and constructing scientific apparatus until after they begin their graduate research The student s research career is greatly facilitated if they acquire the proper foundations in these mechanical practices as an undergraduate The mechanical aspects of building scientific apparatus involve conceptualizing the requirement producing a mechanical drawing that defines the apparatus to fulfill that requirement and fabricating the apparatus to the necessary specifications As an advanced undergraduate or graduate student you will often be required to accomplish all of these tasks As a practicing scientist most often you will perform tasks one and two and submit task three to a professional machine shop In either case understanding the basic principles of metal working glass blowing and materials joining will aid you in making mechanical drawings to communicate your needs and designing apparatus to fulfill these needs Mechanical Drawing The book Building Scientific Apparatus describes the basics of mechanical drawing More complete treatments can be consulted as your skill levels and needs grow Modern mechanical drawing is done with the aid of computer programs referred to a Computer Aided Drafting CAD programs developed specifically for
112. haped CRM Rear panel BNC connector with Z 10 Q provides a nominally 5 V 300 ns logic pulse every time the input signal exceeds the baseline restorer discriminator threshold INH Rear panel BNC connector with Z 10 Q provides a nominally 5 V logic pulse width equal to 6X shaping time when the internal pile up rejection logic detects a distortion of the input signal due to pile up BUSY Rear panel BNC connector with Z 10 Q provides a 5 V logic pulse for the duration that the input pulse exceeds the baseline restorer discriminator PREAMP POWER Rear panel standard ORTEC power connector Amphenol 17 10090 mates with captive and noncaptive power cords on all ORTEC preamplifiers Preamplifier Power Rear panel standard ORTEC power connector Amphenol 17 10090 ORDERING INFORMATION 2 of 3 2 15 08 7 50 AM Amplifier Specifications ORTEC 572A http ortec online com electronics amp 572 20spec htm Model Description 572A Amplifier Alliance Partners Press Release Conf amp Meeting Schedule Careers Quality Policy Privacy Statement Copyright 2007 Advanced Measurement Technology Inc AMETEK 3 of 3 2 15 08 7 50 AM Amplifier Specifications ORTEC 575A http ortec online com electronics amp 575a 20spec htm E Home Applications Contact Us Search SE Products Service Training Download PDF 575A Amplifier Order Online Specifications PERFORMANCE Gain Range Continuously adjus
113. hat energy does channel 1 correspond Now get an unknown y source from the instructor Using references identify the unknown source Other issues you should consider include Do you have a circuit diagram including all equipment device types numbers SETTINGS etc so that you could easily rebuild your setup Have you sketched pulse shapes at different places in the circuit What should you check for when looking at pulse shapes What change in phototube high voltage results in a 100 increase in the observed y ray pulse heights i e channel number in MCA To a first approximation the gamma ray line width that is its Full Width at Half Maximum FWHM is 2 350 and related to the statistical fluctuations in the number of photo electrons N that are collected from the photocathode of the phototube In turn N E thus o E IN lt I VE Thus this ratio measures N Check this by plotting E Joh versus E If the plot is linear then our approximation was valid that is there should be an essentially constant y ray energy required per observed photo electron What is the average y ray energy photo electron in your experiment The inverse question is how many photoelectrons result from a 1 MeV y ray Does this number make sense y ray i e photon cross sections for interacting with the NaI T are rather small in the energy range of a few hundred keV to MeV The photon interaction processes include the photoelectric effect C
114. he INPUT BNC connector on the UCS 30 and set the MODE to PHA Direct In Turn on the power to the UCS 30 Your PC should detect the presence of a new hardware device and may automatically install the re quired software If the software does not load automatically follow the system prompts Remember the location of the software is C Program Files Spectrum Techniques UCS30 UCS 30 Quick Start Guide 3 After you specify location of your software you may see the following screen or similar Hardware Installation A The software you are installing for this hardware Spectrum Techniques UCS20 has not passed Windows Logo testing to verify its compatibility with Windows XP Tell me why this testing is important Continuing your installation of this software may impair or destabilize the correct operation of your system either immediately or in the future Microsoft strongly recommends that you stop this installation now and contact the hardware vendor for software that has passed Windows Logo testing STOP Instalaton Select Continue Anyway and finish the installation Start the UCS 30 program by double clicking on the UCS 30 icon on your desktop Place a Cs 137 calibration source on your detector Next open the Settings pull down menu Click on Energy Calibrate then select Auto Calibrate The system will now auto calibrate This process will take several minutes Once completed the message box will display the current se
115. he more you use the system the more you will become familiar with its operation More detail on operation is provided in the UCS 30 user s manual Contact us if you still have questions comments or problems pertaining to your system or its opera tion Spectrum Techniques 865 482 9937 http www spectrumtechniques com UCS 30 Quick Start Guide 5 Spectrum Techniques SPECTRUM TECHNIQUES LLC 106 Union Valley Road Oak Ridge TN 37830 USA Telephone 865 482 9937 Fax 865 483 0473 e mail support spe techniques com Web Site IK ies ek le ern E 5 SGLOSH EE 7 Hrs taal AUC E 7 Installing SOD rio ue X 7 Uninstalling SoftWare C S 8 Connections On Rear Panel ara 8 EE 10 Pulse Height Analysis PreAmp ln a 10 Pulse Height Analysis Amp In n ea Mae Ee EE E Re eR 10 Pulse Height Analysis Direct D ss ccssssscanscessvncsevantawsbswsssvebennenvtuddsasenesasonesteasedgenanterss 10 M lti Channel Scaling Internal E 11 External Multi Channel Scaling n nasus 13 Messbauer Intermal u un e esse casto tite oe a Ea N ea E A Ea 14 Mossbauer External u n R u ee Nee 15 Operation MT T PR 16 ES 16 Fil Mod E 16 AMP AVADV geet 16 Configuring System EES 18 High Voltage ee c RTT 18
116. he physical dimensions of a high precision wavemeter 2 Corner cube reflectors The metallic corner cube reflectors have an accuracy of 2 of arc Will that be sufficient to keep the laser beams aligned 3 Fringe visibility and diffraction Given as a condition that the beam diameter should not vary more than 10 over the entire range in order to provide good fringe visibility what should the initial waist of the beam be for each laser Hint This requires some basic knowledge of Gaussian beam propagation You should estimate the size of the initial beam waist from each laser by measuring its far field divergence angle REFERENCES 1 Eugene Hecht Optics Addison New York 2002 6 4
117. iagrammed in Fig 3 A small portion of the laser beam is split off by the microscope slide BS reflectance 4 596 per face This reference beam is directed through the flow tube FT perpendicular to its faces and through aperture A and lens L onto detector PD The rest of the laser beam is reflected at mirror M to intersect the reference beam at a point inside FT at an angle of 10 35 This angle is measured as in the transverse velocity measurements above but be sure to account for the differing indices of water and air The tube is filled with water in which a colloidal substance has been suspended CoffeeMate nondairy creamer works nicely and is connected to a pump The suspended particles serve to scatter some of the strong signal beam into the detector where it will be mixed with the reference any frequency shift will then be observable with the spectrum analyzer Note the similarity of this arrangement to a Mach Zehnder interferometer We should expect the signal beam to be Doppler shifted by an amount determined by the projection of the flow velocity onto the direction of the signal beam the derivation of the expected shift is left to the student 5 5 Figure 3 Experimental setup for the flow profile measurements BS is a microscope slide FT is the flow tube and A is an aperture Several important factors must be considered for this experiment to work properly First it is essential that the flow be laminar a tu
118. in cm I 3 x 3 well 1 2 x 1 1 2 1 3 4 x 2 well 5 8 x 1 1 2 Intrinsic Peak Efficiency Legend 4 SOLID CRYSTALS Source at 9 3 cm WELL CRYSTALS Source in weil alt crystal dimensions are in inches Energy MeV Fig 3 6 Intrinsic Peak Efficiency of Various Nal TI Crystals vs Gamma Energy EXPERIMENT 3 7 Mass Absorption Coefficient Pur pose The purpose of the experiment is to measure experimentally the mass absorption coefficient in lead for 662 keV gamma rays References 2 3 and 5 point out that gammas interact in matter primarily by photoelectric Compton or pair produc tion interactions The total mass absorption coefficient can be measured easily with a gamma ray spectrometer In this experiment we will measure the number of gammas that are removed from the photopeak by photoelectric or Compton EXPERIMENT 3 eg interactions that occur in a lead absorber placed between the source and the phototube From Lambert s law ref 1 the decrease of intensity of radi ation as it passes through an absorber is given by Iqe nx 8 where I intensity after the absorber intensity before the absorber u total mass absorption coefficient in cm g density thickness in g cm The density thickness is the product of the density in g cm times the thickness in cm The half value layer HVL is defined as the density thick ness of the absorbing material that will reduce the o
119. in the text box or may be scrolled to the value desired A warning will be issued if you attempt to input a value higher than 1200 volts since this is the highest value that many probes can tolerate without damage If you know that your probe can accept higher than 1200 volts you may increase the voltage up to 2048 volts 18 A gt Lie Amplifier Coarse Gain Amplifier Fine Gain eeoee e eoee J GOSIDNE Weaative eeeeocee LE E E Kel L Amplifier coarse gain may be set by clicking Amplifier fine gain may be directly entered as the radio button next to the desired multiplier a multiplier value between 1 0 and 2 275 in 0 005 increments Spectrum Techniques UCS 30 19 ADC Conversion Gain Conversion Gain represents the number of channels that will be sampled and displayed on the screen Smaller values save as smaller files The conversion gain default setting is maximum channels This is preferred for most scintillation detector applications and generally no adjustment is required For certain applications such as alpha spectroscopy it may be necessary to change this parameter to either 256 512 1024 2048 or 4096 channels Spectrum Techniques UCS 30 Lower and Upper Level Discriminators Loew en L LLD and ULD Lower Level Discriminator and Upper Level Discriminator allow the user to set a value between 0 and 102 3 roughly percent that cuts off the input signal
120. in the light path such that the photon will first hit the double slit and than the polarizer This way the polarizer has no way to influence the photons decision on how to pass the double slit Use the fact that the beam is now polarized along with the mirror polarizer and glass slide supplied to guide the photons passing through each slit to the different PMTs as illustrated in Figure 2 You may want to use a couple lenses to Increase the diameter of the laser beam in order to better cover both slits of the double slit arrangement How does one adjust the discriminator and coincidence to determine whether two photons pass through the two slits at the same time Can one determine on the average how the time distance separating the photons in the box from one another If so what distance do you estimate What is the uncertainty in this measurement Does MIRROR LENSES cem 1 9 ROMS 106 X ATTENUATOR ADDITIONAL ATTENUATION POLARIZING POLARIZER IF NEEDED DOUBLE SLITS Figure 2 Schematic showing photon coincidence measurement the number of photons you observe in each detector agree with what you would predict Does the fact that these slits are different from the slits you used previously impact your conclusions How 4 5 APPENDIX 1 Equipment Manuals Also refer to manuals associated with Experiment 2 on Nuclear Physics PHOTOMULTIPLIER TUBES R1527 HAMAMATSSU k1527P For Photon Counting High Cathode Se
121. incidence of the start and stop inputs eliminates unwanted events from the time spectra via externally nposed energy or timing restrictions The Model 567 also incorporates a built in SCA inhibit feature in which a TAC output is available only if the output pulse falls within the window I restrictions imposed by the SCA This feature may be switched in or out by a convenient front panel switch In addition to its start and stop input gating capabilities the Model 567 Provides for a pulsed or dc level Reset Inhibit signal via a front panel input connector A Reset Inhibit input signal terminates the conversion cycle and maintains a reset condition in hibiting further TAC conversions for the duration of the Reset Inhibit pulse A TAC output pulse that is in process at the time a Reset Inhibit input is received will be completed before converter reset is initiated Valid Start and Valid Conversion out puts are provided for each accepted start and stop input respectively The uration of the Valid Start output indi cates the interval from the accepted start until the end of reset Valid Con version occurs from the end of the Time to Amplitude Converter internal delay after stop to the end of reset I The selectable TAC output width and variable delay which are easily ad justable further serve to make the Model 567 a flexible instrument The output of the TAC may be synchro nized with the stop signal or an
122. ion units to be used keV or MeV Position the marker at the highest channel of the first peak and enter the peak energy value Move the marker to the high point on the second peak to be used for the calibration enter energy number If a 3 point calibration is required continue by moving the marker to the peak channel of the third peak enter its energy and click OK The system will now be calibrated and the marker position will read directly in energy To return to the channel number mode click on Settings click on Uncalibrate 25 Energy Calibration may also be selected using the right mouse button Energy Calibration Units keV EA Cancel Help Energy Calibrate Point 1 Channel 45 keV 4 ET Point 2 Channel 844 keV 662 oe cene Auto Calibrate is a convenience provided for users working in the under 1000 keV energy range Selecting Auto Calibrate will initiate an acquisition sequence that attempts to determine optimum detector voltage and gain settings for a calibrated energy spectrum display This calibration is specifically designed to place the primary peak of a Cesium 137 source at a point approximately 65 of the x axis scale Once located the energy calibration coefficients are calculated to provide a two point calibration 32 and 662 keV Use of other sources will result in erroneous calibration AutoCalibration in Progress SN 00120 Autocalibration will take a few minut
123. is a module that permits linear pulses to be passed only during the time interval that follows each En able input In normal operation the adjusted time interval will allow only one linear pulse to be furnished into the MCA The Timing Single Channel Analyzer determines whether each input pulse amplitude is within the window and gener ates a logic output pulse for each input pulse that satisfies the criteria By adjusting the lower and upper levels of its window the 551 then can determine what portion of the spectrum is gated through for analysis in the MCA This is true since it delivers the enable logic pulse to open the linear gate 21 EXPERIMENT 3 ey EGsG ORTEC From the standpoint of timing one would like to have the logic pulse arrive at the enable input of the linear gate just prior to the arrival of the corresponding linear pulse that is to be gated Since the amplifier provides a bipolar output to the SCA and since the SCA generates an output at 50 of full amplitude on the trailing edge of the positive lobe the SCA output will occur at about 2 us after the onset of the pulse Thus if the 427A Delay is set for 3 us and the 426 Linear Gate width is adjusted to maximum 4 us the gate passes the input pulse for a period from 1 us before the delayed pulse reaches the 426 until 3 us of elapsed pulse time This passes the positive portion of the bipolar pulse which is ail that affects the MCA measurement the negative portio
124. ivergenz bzw ben tigter Fokus Geh useform und AbmaBe Kabelanschluss und Steckerform Netzteil Sprechen Sie uns an Wir finden f r fast jede Laseranwendung die geeignete Strahlquelle 3of4 www coherent de 2009 000 LSR Red HeNe 0 8mW 7 Linear Helium Neon Laser Red 632 8nm 0 8mW Linear 0 46mm Beam Length 178mm Diameter 31 75mmr use PSU 31 2470 la1 2470 000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 0 8mW Random 0 46mm Beam Length 178mm Diameter LSR Red HeNe 0 8mW 7 Random Wee ce Va PSLJ 31 2470 1 270000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC m Helium Neon Laser Red 632 8nm 2mW Linear 0 79mm Beam Length 315mm Diameter LSR Red HeNe 2mW 12 5 Linear BUTANA use PSU 31 2462 aaas Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 2mW Random 0 79mm Beam Length 315mm Diameter LSR Red HeNe 2mW 12 5 Random biss Ges PELL S262 5124620000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC WI Helium Neon Laser Red 632 8nm 4mW Linear 0 80mm Beam Length 396mm Diameter LSR Red HeNe 4mW
125. kets e g esc enter etc 5 10 Setting up Turn on the computer and the 3585A Get into the optics lab directory by typing CD OPTLAB lt enter gt Obtain a signal trace on the analyzer and move the marker to the top of the peak Once this is done you are ready to initiate the program by typing DOPPLER lt enter gt Initializing the program The program will begin by displaying a summary of its operation which will remain on screen until you press lt enter gt The screen will then be cleared and you will be asked for the name of a file in which to store your data Enter this as a root name of up to eight letters followed by a period followed by a three letter suffix H HHH HEH e g MYDATA NEW or GEORGE DAT The computer will then take control of the 3585A and take a datum as an operational test so long as the system does not hang up and no bells are sounded everything is OK You will then be asked to type T enter2 when you are ready to begin data taking or A lt enter gt if for some reason you wish to abort the program Data collection You will next be prompted for the initial position reading of the translation stage Enter this in centimeters or millimeters but always be consistent use one or the other throughout the session The computer will then turn the 3585A COUNTER feature on trigger a trace wait for the analyzer to measure the frequency then request the value of the measurement It will then dis
126. l record above threshold photon signals during a specified time gate width The proper gate width will depend on the type of experiment being performed If only the triggering pulse or pulses are to be recorded the gate width can be relatively short If muon decay events are of interest the gate width must exceed the expected muon lifetime by 4 to 5x Longer than this will introduce noise a significantly shorter gate will make determination of the decay time difficult Threshold Each channel of the QuarkNet card will locally trigger when the amplified PMT pulse exceeds a specified threshold voltage This is illustrated by the dotted red line in the adjacent figure Recall that the threshold voltage must be adjusted by 10x compared to the PMT output to account for amplification on the card Also note that individual channel triggers do not 4 guarantee the gate will open if coincidence triggering has T time over threshold 2 9 been selected Simultaneous PMT events as defined by the coincidence time window are required The time over threshold of an individual pulse can be recorded with a precision of 1 25 ns This time gives an approximate measure of the integrated power and hence the relative energy in the PMT pulses Setup The LabVIEW program Setup vi helps configure the QuarkNet card The goal is to set the PMT bias voltage along with the channel thresholds to acquire reliable data counts The negative going voltage
127. l room light intensities or the full power of the laser will destroy the PMT if it is on Hence the PMT is never to be turned on without the attenuation in place and the lid of the box closed 4 2 4 Light Source Attenuation To decrease the power of the laser beam to a level such that not more than one photon passes through each slit at a time there is a series of 1 2 neutral density filters attenuators available one at 10 X one at 10 X and one at 10 X Fixed to the outside of the light tight box on a sliding window is an attenuator of 10 X This prevents exposure of the PMT to excessive light levels This 10 X attenuation level may or may not be enough to ensure a diffraction pattern produced by one photon at a time You should calculate the required attenuation level and implement that level using the additional attenuators provided as discussed below 5 The Double Slits There are three sets of double slits used in this lab One set is a double slit from Lennox Lasers Those slits are 5 8 um in width and separated by 228 um You should calculate the expected fringe spacing as a function of distance for this double slit geometry The second and third set have slits with a spacing of 1mm in order to allow for integration of polarizers On set of slits has no polarizers and the other set has polarizers installed behind each slit such that the light from one slit is polarized orthogonally to the light exiting the other slit Ex
128. lation spectroscopy and time related studies such as half life decay Constructed in a sturdy fully shielded bench top enclosure with Universal Serial Bus USB computer interface the multi channel analyzer contains many advanced features including computer controlled amplifier and high voltage for PM tubes upper and lower level discriminators on instrument data memory and a comprehensive software package for use under Windows 2000 or higher The UCS 30 requires only an available USB port and is designed to work seamlessly with USB equipped PCs For stability and low noise operation the unit is AC line powered with an auto sensing power supply for 100 250 VAC operation An on board microprocessor acts as the master controller and data storage device as well as the communication link directly to the USB interface The integrated amplifier and high voltage are fully compatible with most standard scintillation detectors eliminating the need for special tube bases and external modules For ease of setup and calibration coarse gain fine gain high voltage and lower and upper level discriminator settings are controlled directly from the desktop computer For operation with other types of detector systems such as alpha spectrometers or single photon counting the scintillation preamp and amplifier can be bypassed by computer control while in the Mode menu which allows direct access to the ADC A 4096 channel ADC with de randomizing b
129. lectric interaction the photon interacts with one of the tightly bound electrons in the material The elec tron in general is knocked out of the atom with an energy given by E hf Ev where f is the frequency of the photon and E is the binding energy of the electron that is involved in the interaction The probability of photoelectric interaction is dependent on the atomic number of the absorbing material and the energy of the gamma or x ray photon Although it is difficult to write out an exact analytic expression for this probability it can be shown that for low energy photons K Z 15 D Ej 15 24 where K is a constant Z is the atomic number and n is us ually between 4 and 5 Procedure The set up for this experiment is the same as for Experiment 3 7 1 Place the CO source 3 8 cm from the Nal detector Accumulate for a time period long enough to get reasonable statistics in the 122 keV line As in Experiment 3 7 X X should be at least 6000 counts 2 Clear the MCA and place the thinnest aluminum ab sorber between the source and the detector Count for the same period of time as in step 1 Repeat for the other two aluminum absorbers 3 Repeat steps 1 and 2 for the other thin absorbers Fe Cu Mo Sn Ta and Pb in the Model 3 Z2 source kit Note The counting time might have to be increased as the atomic number of the absorber is increased EXERCISES a For the three measurements ma
130. lision the gamma imparts the maximum allowable energy for the Compton interaction The energy of the scattered gamma can be determined by solving the energy and momentum equations for this billiard ball collision The solution for these equations in terms of the scattered gamma can be written approximately as E E jr 1 Y 1 2E 1 cos where Ey energy of the scattered gamma in MeV 0 the scattering angle for y Ey the incident gamma ray energy in MeV If 0 180 due to a head on collision in which y is scat tered directly back Eq 1 becomes Ey eae P 4E e As an example we will calculate Ey for an incident gamma energy of 1 MeV 1 MeV Y 1 4 7020MeV 3 The energy of the recoil electron E for this collision would be 0 80 MeV This is true since E E Ey 4 Then the position of the Compton edge which is the maxi mum energy that can be imparted to an electron by the Compton interaction can be calculated by Eq 4 EXERCISES a Calculate the energy of the Compton edge for the 0 662 MeV gammas from Cs Enter this value in Table 3 1 From your plot and calibration curve does this calculation agree with your measured value b Backscatter occurs when gammas make Compton inter 18 actions in the material that surrounds the detector Figure 3 5 was taken from ref 10 and is a good illustration of the various events that can take place in a typical source Nal T dete
131. ll carry out many of the most important operations done in the machine shop using the lathe and milling machine the machines on which the majority of the work in a machine shop is performed Completion 1 2 of the hand crank will require most of the remainder of this laboratory module During this time basic Joining processes such as soldering and welding will be demonstrated so that you are familiar with these techniques Submit your completed hand crank to the instructor for examination If the parts are within tolerance you will have just completed your introduction to mechanical practices in experimental science You can keep the hand crank device REFERENCES 1 Technical Drawing by F E Giesecke et al 12 edition Prentice Hall 2002 ISBN 0130081833 This is an updated version of a book that has been a classic in the area for 60 years 2 Machinery s Handbook by Erik Oberg et al 26 edition Industrial Press 2000 ISBN 0831126663 CD ROM and Cloth This book has a wealth of information and is a standard reference in the metal working industry 1 3 Senior Lab Machine Shop Class Name Spring Semester 2015 Revised 1 15 2014 SAFTEY RULES Please initial each item 1 Wear safety glasses in the shop 2 No open toe shoes such as sandals or flip flops 3 Loose clothing and long hair MUST be secured and or tied back 4 All jewelry must be removed or tucked away this especially includes rings and watches 5 Onl
132. ls can be direct ly OR D by cable Greater than 75 MHz with output width set at minimum Pulse Pair Resolution Better than 12 nSEC with output width set at minimum Input to Output Delay Less than 9 nSEC Multiple Pulsing One and only one output pulse regardless of input pulse amplitude or duration Power Supply Requirements 6 Volts 420 mA 12 Volts Q 165 mA 24 Volts 80 mA 115 Volts AC 65 mA 12 Volts 6 Volts 415 mA 0 mA 24 Volts 80 mA NOTE All currents are within NIM specification limits permitting a full powered bin to be operated without overloading Operating Temperature O C to 70 C ambient Packaging Standard single width NIM module in accordance with TID 20893 and section ND 524 Quality Control Standard 36 hour cycled burn in with switched power cycles Options Call Phillips Scientific to find out about available options MODEL 705 OCTAL DISCRIMINATOR FRONT PANEL DESCRIPTION Standard 1 NIM Packaging in accordance with TID 20893 Threshold Control 15 turn Screwdriver Adjustment Variable from 25 mV to 1 Volt 50 Ohm Input Threshold Monitor Test Point provides a DC Voltage 10 times the actual Threshold Setting 250 mV to 10 V One Complemented NIM Output Quiescently 16 mA 800 mv Goes to 0 mA 0 Volts during output Output Width Control 15 turn Screwdriver Adjustment Variable from 6 nSec to 150 nSec Double a
133. ly the zr interacts before it decays Unlike pions muons do not interact strongly Thus to first order they will decay before they interact The distance a typical E 10 10 eV muon travels is thus Distance 10 10 eV 105 7 MeV 3 x 10 m s 2 197 x 10 s 6 24 62 4 km Where the muon mass m 105 7 MeV This distance is sufficiently great that many muons reach the earth surface In fact at the earth s surface muons are the dominant component of secondary particles from cosmic ray showers Most of the muons are of modest energy by the time they reach ground level Thus some will range out i e stop in a tank of liquid scintillator The study of the decay of these stopped muons is the basis of this experiment Muons decay via the weak interaction similar to the decay of free neutrons and nucleons in nuclei X E u gt v e v Because neutrinos only interact via the weak nuclear force muon decay is one of very few natural processes that only involves the weak interaction The decay rate is actually a measure of the strength of the weak interaction much like the electronic charge is a measure of the strength of the electromagnetic interaction As with nuclear fj decay the energy spectrum of the resultant e is that for a typical three body weak decay dI E dE GZ 12z m E 3 4 E m where dI is the muon decay rate If this is integrated over possible electron energies T It G
134. matically set to the minimum value for which the instrument can still take calibrated measurements if the ST is too small for the RBW and VBW the UNCAL LED will light and the SWEEP TIME increased until it goes off The RBW and VBW can be varied in a 1 3 10 sequence only the ST can be set to any multiple of 0 2 s 7 STATUS When the 3585A is being controlled via the IEEE 488 also know as the HP IB Hewlett Packard Interface Bus and GPIB General Purpose Interface Bus interface on the rear of the instrument the REMOTE LED will be lit and the front panel will be disabled The other three LEDs indicate the status of the instrument with respect to the bus REMOTE control may be overridden and front panel operation restored by pressing the local key 8 TRIGGER The FREE RUN mode should be used Plotting Though not an entry key group the capability to generate a hard copy plot of the displayed frequency spectrum is a useful feature of the 3585A To obtain a plot an X Y recorder must be connected to the X and Y PLOTTER OUTPUT connectors on the back panel of the instrument if the recorder provides a remote pen lift feature this should be connected to the Z output note however that there may be some compatibility problems The plot is initiated by pressing the RECALL on key lower left corner of the ENTRY block then the 8 plot1 key An analog copy of the trace will be sent to the output jacks at a rate which a typical recorder will be abl
135. ment of one half wavelength of M If we translate M by a known distance d and count the number of fringes N on the photodetector we can then determine A from the relationship d NA 2 by measuring N and d If for instance d 30 cm and N 10 fringes then A 0 6 um There are however two limiting factors on the precision with which we can determine A 1 How well we know N and 2 how accurately we can determine d For instance even if dis known with absolute accuracy simple fringe counting would only yield an accuracy of 10 for the determination of the wavelength limited by the lack of information from rounding off to the nearest fringe integer A higher precision is possible by recording the interference fringes and calculating the position between fringes after the last full fringe has been counted such that N is known to a certain number of decimal places N is in fact the round off of arccos 21 I N INT arccos 2I I 1 2 6 1 v Figure 1 Michelson Interferometer Determining N with a higher precision will help but in reality the distance d cannot be measured with the required accuracy One could try to translate M uniformly and to record accurately the fringe count rate Knowing the speed of translation one could determine the wavelength from the fringe counting rate or frequency The problem with that approach is in achieving the required uniformity of motion One could use synchronous motors the frequency
136. mplitude bridged output 32 mA 1 6 Volts across 50 ohms 8 Volt with two 50 ohm terminations Fast Inhibit Input accepts normal NIM logic 500 mV 50 Ohm Impedance Linear summed output Voltage and Current SE NOTE Bin Gate Enable Requirements Disable Switch on Rear Panel permits Inhibiting via Bin Connector Phillips Scientific 13 Ackerman Avenue Suffern New York 10901 USA 914 357 9417 FEATURES MODEL VERSATILE LOGIC MODULE WITH MAJORITY LEVEL SELECTION d FOUR INDEPENDENT CHANNELS ouan ro 125 MHz RATE CAPABILITY PEDES COINC LEVEL e DEADTIMELESS UPDATING OUTPUTS FAST ANTI COINCIDENCE CAPABILITY DESCRIPTION The model 755 logic unit contains four channels of four input logic with veto in a single width NIM module Logic AND OR majority logic fan in fan out and anti coincidence functions can be performed with this versatile module All functions are direct coupled and operate to over 125 MHz with input overlap times as narrow as 1 NSEC Each channel has four logic inputs an anti coincidence input a coincidence level switch and five outputs with common width control The inputs are enabled by connecting the input cable to the desired input eliminating errors often occuring with switched inputs The setting of the coincidence level switch then determines whether a logic OR AND or majority logic function will produce an output After the inputs hav
137. must have USB compatible drivers which are available standard on Windows 2000 and later releases The performance of the USB on older systems may affect the perceived performance of the software so we recommend that you use a Pentium Ill or greater class of microprocessor running at 550 MHz or greater to achieve desirable performance Installing Software Insert the included CD in your CD ROM drive The install program will automatically run Follow the instructions to select the options you want to install The default installation directory is C Program Files Spectrum Techniques UCS 30 Spectrum Techniques UCS 30 7 Example files Spectrum spu files Normal spu contains an uncalibrated spectrum of CS 137 Calibrated spu contains a calibrated spectrum of CS 137 Setup sup files Normal sup has settings used in Normal spu Calibrated sup has settings used in Calibrated spu Library itm files Isotopes itm contains a list of common isotope peaks for use with the IsoMatch function Uninstalling Software Go to the Windows Start Menu select Settings then Control Panel On the Control Panel select Add Remove Software Find UCS 30 double click and follow the instructions Connections On Rear Panel WARNING ELECTRICAL SHOCK HAZARD TO AVOID ANY POSSIBLILITY OF ELECTRICAL SHOCK ALWAYS TURN OFF THE INSTRUMENT POWER BEFORE CONNECTING THE EXTERNAL CABLES DANGEROUS HIGH VOLTAGE CAN EXIST ON
138. n detector The NaI T absorbs the y ray and gives a light burst proportional to the amount of energy absorbed The light is converted into electrons by a photocathode mounted on the input of a photomultiplier tube PMT The PMT is interfaced by the PMT base to a high voltage power supply and amplifier or preamplifier plus amplifier The PMT outputs a current pulse which is proportional to and much greater than the initial photoelectron current Finally a multichannel analyzer MCA digitizes the pulses and stores a histogram of the number of pulses versus pulse amplitude This is shown schematically in Fig 1 Fig 1 Schematic drawing of the electronics for y ray spectroscopy The Nal Th scintillator crystal PMT and PMT Base are a single unit The high voltage applied to the base is negative and less than 1500 V The preamp and amplifier are typically Nuclear Instrumentation Modules NIM powered by a NIM crate The MCA is a stand alone unit 1 Observe y ray energy spectra identify the processes taking place energy calibration the apparatus and determine the identity of an unknown isotope The UCS 30 MCA you will be using has an integral high voltage supply Following the manual Appendix 3 for the MCA connect it to the high voltage input for the PMT Using the Cs source observe the output from the anode output of the PMT base on an oscilloscope using 50 Q termination The pulse will be negative Set the high voltage on the PMT so
139. n of the bipolar pulse is not used The inclusion of a counter in Fig 3 7 permits a direct total of the counts to be observed and the adjustment of the win dow width will limit these to the peak area This simplifies the summing of counts for peak area integrations Figure 3 8 shows how Fig 3 2 might look if the window of the SCA were set properly to just span the Cs photopeak Since the MCA has a live display while it is accumulating it is quite simple to adjust the window of the SCA properly The single channel principle and the control of the linear gate are examined here with individual modules Both func tions are also included in the MCA so the separate modules are not required for other experimental applications Module Settings Use the same settings for the high voltage power supply preamplifier and amplifier that were used for Experiment 3 1 Set the 426 Linear Gate for Normal with its Gate Width control fully clockwise for 4 us Set the 875 Counter for count and use the Positive input from one of the Pos Out connec tors on the 551 Timing SCA reset the 875 Counter to zero Set the 551 Timing SCA for Normal operation the Lower Level control at 030 the Upper Level control fully clockwise 113 PREAMPLIFIER 905 3 Nal TI 266 SCINTILLATOR AND PM BASE PHOTOTUBE SOURCE 556 HV POWER SUPPLY 575A AMPLIFIER PHOTOPEAK E 0 662 MeV SINGLE CHANNEL AE WINDOW Counts Chan
140. nSEC and the output pulse shapes are One input per section LEMO connector accepts optimized when the bridged outputs are 50 ohm NIM level logic signal 500 mV 50 ohm input terminated Width Control One control per section 15 tum screwdriver adjustment Outputs are continuously variable from 4 nSEC to 1 uSEC better than 0 15 C Updating Operation The output pulse will be extended if a new input pulse occurs while the output is active This provides deadtimeless operation and 10096 duty Cycle can be achieved impedance direct coupled less than 5 input reflection for a 1 nSEC risetime protected against damage 50 volt input transients Requires a 3 5 nSEC minimum input width in time with the input pulse leading edge to inhibit Bin Gate Rear panel slide switch enables or disables the slow bin gate via the rear connector Signal levels are in accordance with the TID 20893 standard GENERAL PERFORMANCE Functions Logic AND OR majority logic and logic fan in fan out All functions have leading edge inhibit with standard ized outputs Rate i 150 MHz minimum input to output Typically 160 MHz Double Pulse Resolution Less than 6 5 nSEC Typically 6 nSEC with output width set at minimum Input to Output Delay Less than 8 nSEC Multipie Pulsing One and only one output pulse regardless of input pulse amplitude or duration Power Supply Requirements 6 V 400 mA 6 V 250 mA 12 V 9 165 mA 12 V 0 mA
141. near 0 95mm Beam Length 637mm Diameter LSR Red HeNe 17mW 25 Linear Wee rie use PSU ST 2447 31 2447 000 Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC LSR Red HeNe 35mW 40 6 Lin Helium Neon Laser Red 632 8nm 35mW Linear 1 25mm Beam Size 1030 x 79 x 66mm use PSU 31 2488 biss mm Power Supply HeNe 115 230VAC HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Red 632 8nm 17mW Random 0 95mm Beam Length 637mm Diameter LSR Red HeNe 17mW 25 Random ayan use PSU 31 2447 51 2447 000 Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC Helium Neon Laser Orange 612 0nm 2mW Random 0 80mm Beam Length 396mm 44 5mm LSR Orange HeNe 2mW 15 5 Rdm Diameter uso PSU 31 2405 1405 00 Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC LSR Yellow HeNe 2mW 18 Random Helium Neon Laser Yellow 594 1nm Random 0 75mm Beam Length 456mm use PSU 31 2413 31 2443 000 Power Supply HeNe 115 230VAC Hehe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC 5122264000 LSR Green HeNe 0 3mW 15 5 Rdm Helium Neon Laser Green 543 5nm 0 3mW Random 0 66mm Beam Length 315mm 44 5mm Diameter use PSU 31 2421 HeNe Power Supply with Key Switch Interlock and Emission Indicator 115 230 VAC for HeNe 31 2421 000 Pow
142. nel The dashed curve represents the portion that was gated away with the Linear Gate Channel Number Fig 3 8 Cs Spectrum with the Linear Gate at 1000 divisions and Delay at minimum for 0 1 us Set the 427A Delay Amplifier for a 3 us delay Procedure 1 Place the Cs source from SK 1G about 4 or 5 cm from the crystal face Accumulate a spectrum in the MCA while adjusting the E and the AE window on the 551 Timing SCA Set the window so that it just brackets the photopeak as in Fig 3 8 You are now ready to make the first measurements 2 Clear the MCA and reset the counter to zero Start both at the same time and accumulate for a period of time long enough to obtain about 6000 counts in the counter Record 427A DELAY AMPLIFIER Readout ACE 2K MCA System 875 COUNTER Fig 3 7 Block Diagram of Electronics for Gamma Ray Spectrometry System with a Linear Gate 22 EXPERIMENT 3 E E a LLLLeLUIlCCeCOeCCU C the total elapsed time for the measurement the average dead time from the MCA and the count in the counter Read out the analyzer and then clear both the MCA and the counter 3 Place the first lead absorber between the source and the detector as in Experiment 3 7 and accumulate for the same period of time that was used in step 2 above Record only the counter counts and the total elapsed time It isnot necessary to read out the MCA for each spectrum since
143. ng range normally about 1000 V 113 Scintillation Preamplifier Set the Input Capacity switch at 200 pF The output pulses will be positive 575A Amplifier Positive input and Bipolar output Shaping time set to 0 5 usec The gain will be adjusted during the experiment Multichannel Analyzer PHA Analysis mode 1000 channels are adequate for this experiment Procedure 1 Place the Cs source from SK 1G Ey 0 662 MeV 2 cm in front of the Nal TI crystal 2 Adjust the coarse and fine gain controls of the linear amplifier so that the 0 662 MeV photopeak for Cs falls at approximately channel 280 For the illustrations shown in Figs 3 2 and 3 3 the gain of the system has been set so that 1 MeV falls at about channel 420 to 425 Since the system is linear 2 MeV would therefore fall at approximately channel 840 to 850 350 300 Photopeak 0 662 280 Compton edge 0 478 180 Backscatter 0 184 100 250 Resolution x 100 32 x 100 280 11 5 200 BACKSCATTER Counts Channel 150 100 50 Event Energy MeV Channel No 3 Accumulate the Ce spectrum for a time period long enough to determine the peak position Figure 3 2 shows a typical Cs spectrum that has been plotted Although these spectra are usually plotted on semilog graph paper the figures shown in this experiment are plotted on linear paper to point out some of the features of the spectra 4 After the Cs spectrum has been
144. nger than 5 muon lifetimes data accumulated at long times will represent the noise background The background data introduces a constant offset on the statistics that can be subtracted The desired decay events are statistically rare so an hour or more may be needed to accumulate a useful data set When sufficient data is collected stop the program The time events are all written to the specified data file For the analysis setup an appropriate histogram on a semi log plot The slope of the linear fit is the measured muon decay lifetime Calculate the experimental uncertainty and compare the lifetime to the accepted value REFERENCES 1 a W R Leo Techniques for Nuclear and Particle Physics Experiments 2nd Ed Springer Verlag New York 1993 Ch 1 1 b C M Lederer and V S Shirley Table of Isotopes Tth Ed Wiley New York 1978 2 W R Leo Ch 2 Sect 2 7 Interaction of Photons with Matter 3 W R Leo Ch 7 Scintillation Detectors 4 W R Leo Ch 8 PMTs 5 W R Leo Ch 9 Sect 9 7 Scintillation Detector Operation 6 W R Leo Ch 11 Pulse Signals 7 W R Leo Ch 12 NIM Electronics 8 W R Leo Ch 14 Pulse Signal Shaping and MCAs 9 W R Leo Ch 15 Pulse Height Spectra and MCAs 10 See Appendix 2 AN34 Experiments in Nuclear Science 3rd Ed EG amp G ORTEC 1984 11 G F Knoll Radiation Detection and Measurement Ch 2 2nd Ed Wiley New York 1989 12 Harshaw Radiation Detectors Harshaw
145. niature OEM style with exposed 147 mm dia x max 51 F a Aqusan 414 mons 0223 132 00 Sys FVMB4 670nm 1mW E VP Adj Pd Wes horas e ee Eliptical Beam 1 3 4 2mm Variable Power Control ants 44 7 met dia x max 51 1 13x42 Adjustable 914 none Switcher e VLM 11mm diameter package 670nm 4 2mW Internal 3 3V Regulator Elliptical Beam 1 7 x aft 3558 0222 494 00 Sys FVLM om 670nm 4aW E Adj 5 6 mm Operates at 4 5 6 VDC Adj Tool included to change focus Black Anodized case Tr78 M7 mm dia 42 Vrx56 0x02 152 RCA Center 0220 857 00 Sys FVLM2 670nm 4mW E Adj VLM2 670nm 4 2mW Adjustable Focus Elliptical Beam 4 x 1mm 8 14 7 mmdiaxmax514 4 2 4x1 03x12 609 none 0223 103 00 Sys FVLM2 670nm 1mW MVP Adj Hee E Ge Focus Elliptical Beam 4 x tmm Modulation and Variable tg 44 7 mm dia xmax514 085 4x1 Adjustable 609 none 1008538 Sys FVLM2 635nm 10mW E VP Adj s Gus 10 5mW Adjustable Focus Elliptical Beam 4 5 x 1 2mm Variable Power Control ba 44 7 mn dia x max 54 10 4 5x1 2 Adjustable 588 none 31 0532 000 Sys FVLM2 635nm 4mW E CW Adj VLM2 635nm 4mW Adjustable Focus Elliptical Beam 4 7 x 1 3mm Phono Plug Connector f8 14 7 mmdiaxmax514 4 2 4 7x13 0 2x08 990 eler Item Number Description Extended Description 0221 145 00 Sys LG2 30Deg 670nm 1 8mW VLM2 Line Generator 670nm 1 8mW 30 Degree Fan Angle 14 7 mm dia 18 1
146. ns MODEL 755 QUAD FOUR FOLD MAJORITY LOGIC UNIT FRONT PANEL DESCRIPTION Standard 1 NIM Packaging in accordance with TID 20893 Output Width Control l5 turn Screwdriver Adjustment Variable from U i 4 nSec to 1 uSec Four Logic Inputs Accepts Normal NIM Logic 500 mV 50 ohm Impedance Two pairs of bridged outputs each pair delivers 32 mA 1 6 Volts across Level Switch Seiects 50 ohms 8 Volt with Logical OR AND both outputs 50 ohm or Majority Logic terminated Functions i Four Position Coincidence One Complemented NIM Output Quiescently 16 mA 800 mV Goes to 0 mA 0 Volts during output Fast Inhibit Input accepts normal NIM Logic 500 mV 50 ohm Impedance NOTE Bin Gate Enable Voltade ang turrene Disable Switch on Rear Requirements Panel permits Inhibiting via Bin Connector Phillips Scientific 13 Ackerman Avenue Suffern New York 10901 USA 914 357 9417 ORTEC 550A Single Channel Analyzer Ideal for selecting a range of pulse amplitudes from a spectroscopy amplifier for counting on a ratemeter or counter timer Provides the excellent stability resolution and dynamic range demanded by high resolution detectors Four operating modes Integral Normal independent upper and lower levels Asymmetric window Symmetric window DC coupled for high counting rates SCA outp
147. nsitivity with Low Noise Photocathode FEATURES Spectral Response 185 to 680 nm Cathode Sensitivity LUMINOUS 2 2 eren nana kcu acu SEENEN raura 60 u A Im Radiant at 400nm 60 mA W Anode Sensitivity at 1000V Luminous 400 A Im Radiant at 400nm 4 0 X 105 A W Low Dark Current 0 1 nA Low Dark Counts R1527P 10 cps Hamamatsu R1527 features high cathode sensitivity high cur rent amplification and low dark current Variant tube R1527P specially selected for photon counting application is also available The R1527 is useful for fluorescence chemiluminescence Raman spectroscopy and low light level detection Figure 1 Typical Spectral Response GENERAL Parameter Description Vaiue i 103 Spectral Response 185 to 680 Wavelength of Maximum Response 400 Photocathode Material Low noise bialkali Minimum Effective Area 8X 24 Window Material UV glass TPMSBO0025EA CATHODE RADIANT SENSITIVITY 102 Dynode Secondary Emitting Surface Low noise bialkali Structure Circular cage Number of Stages 9 101 QUANTUM EFFICIENCY Direct Interelectrode Capacitances Anode to Last Dynode 4 Anode to All Oth
148. nt source type with two pairs of negative bridged outputs and one complement for each channel When only one output of a bridged pair is used a double amplitude NIM pulse 32 mA is generated for driving long cables with narrow pulse widths The outputs have transition times of typically 1 0 nSEC and their shapes are virtually unaffected by the loading conditions of the other outputs INPUT CHARACTERISTICS A B C D OUTPUT CHARACTERISTICS Four inputs per section LEMO connectors accepts NIM level logic signals 500 mV 50 ohm input impedance direct coupled input reflections are less than 5 for a 1 nSEC rise time inputs are protected against damage from 50 volt input transients Inputs respond to a 1 nSEC or greater input width Five outputs per section two pairs of negative bridged and one complemented NIM The two pairs of bridged outputs are quiescently 0 mA and 32 mA during output 1 6 V into 50 ohms or 8 V into 25 ohms The complemented output is quiescently 16 mA and O mA during output Risetimes and falitimes are less than 1 5 Fast Veto nSEC and the output pulse shapes are One input per section LEMO connector accepts optimized when the bridged outputs are 50 ohm NIM level logic signal 500 mV 50 ohm input terminated Width Control One control per section 15 tum screwdriver adjustment Outputs are continuously variable from 4 nSEC to 1 uSEC better than 0 15 C Updating Operation The ou
149. o 10 V The SCA OUT is generated for pulse amplitudes that exceed the lower level threshold but do not exceed the upper level threshold ORTEC ASYM WINDOW In the ASYMMETRIC WINDOW mode the lower limit of the window is adjustable from 20 mV to 10 V using the LOWER LEVEL dial The WINDOW dial adjusts the width of the window from 0 to 1 V The SCA OUT is generated for pulse amplitudes between the upper and lower limits of the window SYM WINDOW In the SYMMETRIC WINDOW mode the center of the window is adjustable from 20 mV to 10 V using the LOWER LEVEL dial The WINDOW dial adjusts the width of the window from 0 to 1 V The SCA OUT is generated for pulse amplitudes between the upper and lower limits of the window INT EXT LL REF A rear panel locking toggle switch selects either the front panel LOWER LEVEL dial INT position or the rear panel LL REF input EXT position for controlling the lower level threshold INPUTS INPUT Front panel BNC connector accepts unipolar or bipolar linear signals for pulse amplitude selection in the range of 20 mV to 10 V dc coupled The minimum input pulse width is 100 ns The maximum amplitude of signal plus dc offset is 12 V Input impedance is approximately 1000 Q Front panel test point wired to the INPUT connector through a 470 9 resistor IN Rear panel BNC connector identical to INPUT connector LL REF Rear panel BNC connector accepts a dc voltage from an external source for
150. ompton scattering and pair production What photon cross section is most directly related to the total conversion of the y ray to visible light in the energy range of this experiment Is this the dominant cross section at these energies What is the dominant photon interaction Does this dominant process result in events in the observed y peaks If not how do events get to be in the peak 2 Measure y ray attenuation coefficients Just as y rays interact with the NaI T to be detected or with lead shielding to reduce background counts y rays interact with all matter The physical processes include the photoelectric effect Compton scattering and pair production as noted above These cross sections are combined in a variety of ways depending on the precise definition into an absorption or attenuation coefficient u Thus following a distance X an initial number of y rays N 0 is attenuated to a final number N X N X N 0 e Because the photon cross sections change rapidly with energy and depend on the absorber material s nuclear charge it is interesting to measure u at different energies and for more than one absorber material To measure the energy dependence of u start with the Cs source and the MCA To know N 0 for each y ray line you need to take and fit a MCA spectra with no absorber and for a known live time interval Then take additional spectra with different thickness of absorber and for different types of absorb
151. on with computer PREAMP POWER DB 9 connector supplies 12v power for External preamplifier Spectrum Techniques UCS 30 9 NOTE An OPTIONAL 24v preamplifier power output is available to ensure compatiblity with germanium detectors Analysis Modes Pulse Height Analysis PreAmp In This is the normal operating mode for collecting sample gamma emission spectra The amplitude of each detector pulse is measured by the ADC and stored as an amplitude energy spectrum The X axis is scaled to the selected channels and the Y axis is scaled for the counts for each channel Y axis counts that exceed the maximum Y axis value are wrapped they no longer are scaled to the Y axis and they appear in a different color Pulse Height Analysis Amp In trum Techniques UCS30 Li Mode Spectrum Techniques UCS 30 Similar to the PHA PreAmp In operating mode except that the incoming signal bypasses the instrument s internal Pre Amplifier The amplitude of each detector pulse is measured by the ADC and stored as an amplitude energy spectrum Pulse Height Analysis Direct In Similar to the PHA PreAmp In operating mode except that the incoming signal bypasses both the instrument s internal Pre Amplifier and Amplifier The amplitude of each detector pulse is measured by the ADC and stored as an amplitude energy spectrum 10 eh ERE Multi Channel Scaling Tnternal PELT Techniques U
152. onal basis from the spectral data To aid in the identification of nuclides the UCS 30 contains a unique peak labeling feature named ISOMATCH Providing the unit is accurately energy calibrated the user may select a nuclide from the library and the corresponding characteristic emission lines are superimposed on the spectrum along with isotope and energy information Using this feature users may quickly check a spectrum and visually identify the emission components for each nuclide present The ISOMATCH libraries may be created or customized using a text editor When operating in multi channel scaling mode the system may be calibrated in time units for direct readout from the cursor Both linear and logarithmic vertical display ranges are included which can be useful when performing decay studies Spectrum files can be transferred from the ICS 10 DOS program and the ICSW 16 Windows program to the UCS 30 Windows version format Most functions may be accessed by more than one method All the functions can be accessed from the Pull Down Menues some from the Tool Bar Buttons or by the mouse If the function has a Tool Bar Button its symbol will be shown on the left hand side of the description Spectrum Techniques UCS 30 6 Screen View y b Spectrum Techniques UCS 30 Live Mode Chamel 30 Counts 3947 Installation System Requirements The UCS 30 instrument uses a Universal Serial Bus USB to communicate with a PC The PC
153. ontinued Specifications PERFORMANCE Time to Amplitude Converter TIME RESOLUTION FWHM lt 0 01 of full scale plus 5 ps for all ranges TEMPERATURE INSTABILITY lt 0 01 C 100 ppm C of full scale plus 10 ps C 0 to 50 C DIFFERENTIAL NONLINEARITY Typically lt 1 from 10 ns or 2 of full scale whichever is greater to 100 of full scale INTEGRAL NONLINEARITY lt 0 1 from 10 ns or 2 of full scale whichever is greater to 100 of full scale RESET CYCLE Fixed 1 0 us for X1 and X10 Multipliers fixed 5 us for X100 Multiplier and fixed 50 us for X1K and X10K Multipliers Occurs after Over Range Strobe cycle or Ext Strobe Reset cycle START to STOP CONVERSION TIME Mini mum S5 ns Single Channel Analyzer THRESHOLD INSTABILITY lt 0 01 C 100 ppm C of full scale 0 to 50 C refer iced to 12 V NIM bin THRESHOLD NONLINEARITY lt 0 5 of full scale CONTROLS Front Panel RANGE ns Three position rotary switch se lects full scale time interval of 50 100 or 200 ns between accepted Start and Stop input signals MULTIPLIER Five position rotary switch ex tends time range by a multiplying factor of 1 710 100 1K or 10K DELAY 20 turn screwdriver adjustable po tentiometer varies the delay of the TAC and SCA outputs from 0 5 us to 10 5 us relative to an accepted Stop input signal operable in the Int Strobe mode only STROBE MODE Two position locking toggle Switch selects
154. opagates as a wave but is detected as particles The quantum nature of this experiment is ensured by the fact that the photons will pass individually though the slit and therefore it is not in the classical limit of a large number of photons Despite the fact that single photons pass through each slit one at a time you will find that the photons still create a standard Young s double slit interference pattern You should review the classical Young s double slit experiment and the results to compare with what you see here The basic experimental approach is to attenuate a light source incident on a double slit to such a degree so as to insure single photons pass through each slit that is without having one photon in each slit simultaneously The spatial variation in the position at which these photons strike a plane behind the slits is then recorded and the double slit interference pattern is reproduced Besides simply arguing the single photon nature of the experiment from the degree of light source attenuation you will also demonstrate the quantized nature of light experimentally by using coincidence techniques to show that there is not a photon in each slit at any given time Apparatus 1 Light Source The choice in light source was dictated by several requirements First a narrow enough frequency spectrum is needed such that the interference fringes will be easily resolved Second the wavelength of light needs to be easily detected wi
155. ory reports In addition each student will be given a one half hour oral final exam Laboratory performance and the oral exam will be respectively 85 and 15 of your final grade Attendance is required You will need to complete four laboratory elements that must include laboratories 1 and 2 Laboratory 3 is strongly recommended and can only be taken following completion of Laboratory 1 The time required to complete a lab element will vary depending on the particular lab however plan to spend roughly four weeks of class sessions on each Lab reports will be turned in for grading within 2 weeks of their completion If experiments are performed with a partner each student should keep their own laboratory note book and write their own laboratory reports Laboratory Reports Use the standard format for laboratory reports Abstract Introduction Theory Experimental Apparatus Results Discussion amp Conclusions References References are to be to peer reviewed journal articles or books NOOR Q Reports should appear as they would in a scientific journal with graphics embedded in the text The write up for Laboratory 3 has some unique requirements as specified in the manual for Laboratory 3 493L LABORATORY SAFETY Department of Physics and Astronomy University of New Mexico Elements of this laboratory class pose certain hazards No instructions can substitute for common sense If you are unclear about some
156. ov SLTC radiation Several types of radioactive sources will be encountered in the laboratory Sources you will use in this laboratory are sealed low activity sources and therefore present no health issues NEVER eat drink or smoke in the laboratory Wash your hands at the conclusion of each laboratory session Sealed gamma ray sources having activities of 1 uCi can be handled with your fingers For sealed and unsealed source of roughly 10 uCi or greater use tongs or other devices Do not handle directly Certification Return this signed statement to the instructor have read and understood the document on laboratory safety for Physics 493L and agree to follow these rules when in the laboratory Your Name Printed Signature Date LAB 1 Mechanical Practices in Experimental Science Paul R Schwoebel and Anthony Gravagne Purpose Introduce the student to mechanical practices used in the design and construction of scientific apparatus through exposure to mechanical drafting and the fundamental operations performed in a machine shop Reading Assignment Chapter 1 Building Scientific Apparatus 3rd edition by John Moore Christopher Davis and Michael Coplan Perseus Books Cambridge MA 2003 on reserve in the Centennial Livrary Familiarity with the material in Chapter 2 is useful for future reference Background The experimental scientist must routinely design and construct scientific apparatus in order to conduct researc
157. p to end of reset E impedance Z S10 Rise Time 50 ns Fall Time lt 50 ns SCA Front and rear panel connectors pro 5 vide NIM standard slow positive logic E x signals 1 Amplitude Nominally 5 V Complement sig nal selectable by PWB jumper Time and Width From start of TAC linear out Sr put to either end of reset or end of linear e output PWB selectable Factory set at end ot reset 1 Impedance Z z10 n m Rise Time lt 50 ns Fall Time 50 ns 210 mA 24 V 165 mA 12 V 220 mA WEIGHT L E Net 1 4 kg 3 Ib Shipping 3 2 kg 7 Ib DIMENSIONS NIM standard double wide module 6 90 X 22 13 cm 2 70 X 8 714 10 per TID 20893 Rev Ordering Information To order specify Model Description 567 Time to Amplitude Converter SCA ds Phillips Octal Scientific Discriminator FEATURES INDIVIDUAL THRESHOLD AND WIDTH CONTROLS LINEAR SUMMED OUTPUT BOTH FAST VETO AND BIN GATE LOW COST EIGHT 8 CHANNELS IN A SINGLE WIDTH NIM MODULE DESCRIPTION The Model 705 was specifically designed for modern experiments with large counter arrays offering high per formance and reliability at a reasonable cost The 705 features eight 8 totally independent channels with in dividual threshold and width controls In addition a fast veto input and a summed output are common to all channels Each channel has a threshold adjustment continuously variable from 10 mV to 1 Volt with a fron
158. perimental Procedure Arrange the apparatus such that you can see the double slit interference pattern using the Lennox Laser slits by opening the window in the box to remove the 10 X attenuator Align the pattern such that it falls on the entrance window to PMT 1 It will be useful to align an antinode over the entrance slit The quantum nature of this experiment is insured by the fact that the photons pass individually through the slit and therefore that it is not in the classical limit of a large number of photons Hence you must now determine the degree of laser light intensity attenuation required to reach the single photon limit This determination is made by a time of flight argument using the speed of light the dimensions of the flight path in the light tight box and the laser power Other considerations may involve the aperture effect of the double slits Insert appropriate additional attenuation if needed using the attenuator holder and attenuators supplied Seal the boxes close the window and apply high voltage to PMT 1 Observe its output on the oscilloscope Adjust the gain of PMT 1 until your signals are roughly 30 mV or possibly greater Using the discriminator and scaler count the number of photons you see in a given time interval Scan the entrance slit PMT assembly horizontally using the micrometer while recording the number of counts you see as a function of position Is the Young s double slit interference pattern observed Are
159. play on the computer CRT the number of data points taken thus far the current position of the translation stage and the current frequency measurement It will also move the spectrum analyzer MARKER to the measured frequency so that you can determine whether the counted frequency corresponds to the Doppler shift signal You will then be asked whether to keep the datum or reject it The datum should be rejected if the reported does not correspond to the reading from the translation stage in which case you moved to the peak of the Doppler shift signal in which case you should move the MARKER manually to that position using the CONTINUOUS ENTRY knob on the 35854 front panel this will prepare the instrument for the next measurement After keeping discarding the datum you will be prompted with Type enter to continue space enter to change position or STOP to quit Respond accordingly If the first option is chosen a new trace will be triggered and a new measurement taken If you want to change position you will be prompted for the new position move the translator type in the new reading and press enter to indicate a new measurement Respond with STOP if you are finished taking data or if you wish to quit the session the output data file will be closed and the 3585A will be returned to manual control Suggestions You will want to take several data points at each position to get an idea of the accuracy of your measurements
160. r it is good practice to Never look directly at the beam of the laser Keep the laser beam in one horizontal plane close to the table Never bend down to the table level We have purposely chosen to have the optical table surfaces as low as possible which reduces the chances of having your eyes at the beam height Low chairs are not allowed in the lab Sitting accommodations are limited to high stools High Voltage amp Line Voltage Safety You should supplement the following general electrical safety description with reading at http www osha gov SL TC electrical index html The following guidelines are to protect you from potentially deadly electrical shock hazards as well as the equipment from accidental damage Note that the danger to you is not only in your body providing a conducting path particularly through your heart Any involuntary muscle contractions caused by a shock while perhaps harmless in themselves may cause collateral damage due to contact with sharp edges and points inside various things like stamped sheet metal shields and the cut ends of component leads In addition the reflex may result in contact with other electrically live parts Don t work alone because in the event of an emergency another person s presence may be essential Always keep one hand in your pocket when near a line powered or high voltage system Radiation Safety For a complete introduction to radiation safety see http www osha g
161. r power stebllty and lowinoles EN am 44 5 mm dia x218 mm 30 29x10 02x04 1000 5 Pin DIN Diameter x 218mm Length Item Number 1056830 Description Radius 635 25 635nm 25mW Adj RADIU Extended Description Radius 635nm 25mW OEM Adjustable Focus Beam Size 2mm Laser Size 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 1000 5 Pin DIN 1051385 Radius 635 25 635nm 25mW CDRH Radius 635nm 25mW with CDRH Control Box 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 25 1 13 1000 5 Pin DIN 1058455 Radius 635 25 635nm 50N MVP ads 635nm 25mW OEM 44 5mm Diameter x 218mm Length Modulation and Variable Power 44 5 mm dia x218 mm 1 13 4000 lei Din 1008053 Radius 635 25 635nm 25mW OEM Radius 635nm 25mW OEM 44 5mm Diameter x 218mm Length 44 5 mm dia x218 mm 25 1 13 1000 5 Pin DIN Item Number Description Extended Description 0221 698 01 Sys VHK2 3 1 635nm 1mW 1mm C VLM2 635nm 0 95mW Circular Beam 1mm 14 7 mm dia x34 3 mm 0 95 14 07 914 none 31 0441 000 Sys VLM2 3 1 635nm 1mW 3mm C VLM2 635nm 0 95mW Circular Beam 3mm with Phono Plug Connector 14 7 mm dia x34 3 mm 0 95 3 04 990 Pus 2 VLM3 635nm 1mW Beam Size 3mm Circular Miniature OEM package Adjustable 0222 458 00 Eeer Focus with port to add thread lock No leads use Power Pins Label shipped loose 9 58 mm dia i 3 04 6 none 0222 20 00 Sys
162. r shifted beams the signal will then disappear and by translating the wheel the signal frequency should then shift Once the data are taken you will also need the diameter of the wheel a direct measurement of its rotation rate and the wavelength of the laser From these you should be able to determine the rotation rate of the wheel and to estimate the precision of your measurements Discuss the precision of your results and the important error sources Transverse speed measurement As pointed out earlier the Doppler technique is applicable only for measuring longitudinal velocities There is in fact a transverse Doppler effect but it goes as Vic and so is observable only for relativistic particles However it is possible to measure the transverse velocity of an object using light scattering The setup is as shown in Fig 2 The laser beam is split and reflected by BS and mirror M onto the edge of the fast rotating wheel W intersecting at its surface at an angle a to form a fringe pattern of spacing L This spacing should be too small to be visible with the unaided eye but much greater than the wavelength of light 1 e between 5 and 50 um As it is determined by the beam crossing angle o you must position BS and M appropriately The most accurate way to find this angle is to measure the separation of the beams some distance from their intersection take several such measurements at different positions to obtain an accurate value for a
163. rangement in the first part of this experiment is identical to a Michelson interferometer and the expected frequency shift of the light can be derived by considering the object to be equivalent to the translating mirror From this point of view the beat note signal is just the rate at which fringes pass the detector In the second fast wheel part the measured frequency is the quotient of the transverse speed of the wheel and the fringe spacing which is determined by the wavelength of the light used and the angle of intersection of the two beams For the third water flow part of the experiment the angle of intersection of the 5 2 beams and the refractive index of water must be taken into consideration The necessary derivations are left to the student and a summary thereof should be included in the lab write up All three parts of this experiment involve measuring the light scattered from a large number of randomly placed scattering centers Given that the characteristic frequency of interest is the same for all of the scatterers the signal from each will be randomly phased so one might expect any modulation at that frequency to average out Furthermore since the collected light is due to scattering the total intensity can vary wildly at frequencies unrelated to the one in which we are interested Considering such a small signal to noise ratio how can we expect to measure anything Hint The net signal from an ensemble of randomly phased so
164. rbulent flow will give Doppler shifts over a wide range of frequencies blurring the spectrum analyzer peak until it becomes unrecognizable Second we must limit the size of the particular scattering region at which we are looking for each measurement if the volume is large there will again be a range of frequencies in the spectrum This is the function of the lens it images a small region within the intersection volume onto the detector Third we must restrict the range of scattered wave vectors light scattered off at different angles will have different Doppler shifts again broadening the frequency peak This is the function of the aperture A although the lens will image any light scattered from the volume of interest onto the detector the aperture blocks all but that light propagating along the direction of the reference beam A vertical slit could be used instead Why Special care must be taken to obtain a signal which is sufficiently clean for taking measurements The detector should be placed so that it receives the reference beam directly The position of the lens is particularly critical Initially determine the approximate height and transverse position by centering the lens on the reference Then find the longitudinal position in the following manner Translate the tube so that the beams intersect at the face nearest the detector Block the beams with a thin sheet of paper and adjust the positions of L and PD to image the beam spot on
165. rce to learn the range of y ray energies and the number of distinct lines Then you should consider building a cave from lead bricks to shield the Nal TI detector from extraneous i e background y rays Where does this background come from You should also experiment with the distance between the source and the front of the NaI T detector Does this make any discernable difference other than count rate A good rule of thumb is to place the source at least 2 detector diameters from the detector Why The effective solid angle of the detector is then zu 4zd where r is the detector radius and d is the source to detector distance With your optimal setup you should accumulate a spectrum from each of the y ray sources Do the spectra look different from your first spectra How and why Do the spectra look like the text book spectra Identify as many of the features and lines as you can Now take individual spectra for a couple sources such as the Cs and Co You may also want to try the Co source if it is not too old Do this in as short a time period as is possible Repeat to be sure that your peaks have not drifted Determine the channel numbers for the center of each y ray line If the DAQ electronics and the MCA are linear there should be a linear relation between peak channel number and y ray energy To check this make a plot of channel number versus energy Are the points in a line Does the curve go through 0 0 or is there an offset To w
166. rce to the activity of a standard Cs source that will be supplied by the laboratory instructor For convenience call the standard source S1 and the unknown source U1 Procedure 1 Place the S1 source about 4 cm from the face of the detector or closer if necessary to get reasonable statistics and accumulate a spectrum for a period of live time select able on the analyzer long enough to produce a spectrum similar to Fig 3 2 2 Use the cursor to determine the sum under the photo peak In the example shown in Fig 3 2 this would corre spond to adding up all counts in channels 240 through 320 Define this sum to be S 3 Erase the MCA spectrum Remove source 1 and replace it with source U1 positioned exactly the same distance from the crystal as the S1 source was Accumulate a spectrum for the same period of live time that was used in step 1 Sum the peak as in step 2 4 Erase the spectrum from the MCA Remove the U1 source and accumulate background counts for the same period of live time that was used in steps 1 and 3 above 5 Sum the background counts in the same channels that were used for the photopeaks in steps 2 and 3 above Call this sum X 19 EXPERIMENT 3 dl EGzG ORTEC x M EXERCISE Solve for the activity of the U1 by using the following ratio activity of ST Zg4 p Since the efficiency of
167. re to restore the UCS30 to a previous condition File Load Library Allows loading of an Iso Match library file itm File Save Library Allows saving of an Iso Match library file itm File Print Allows the user to print the displayed spectrum File Print Preview Allows the user to preview the spectrum as it will be printed File Print Setup Allows the user to adjust the printer parameters before printing File Exit Spectrum Techniques UCS 30 35 Closes the application Edit Experiment Experiment Lab Test 234 432 Determine the unknown isotope Solly 123 45 678 Acme 98765 a Peaks indicate that this is Cs 13 Edit Experiment provides a means of inserting text into spectral file headers for referencing specific measurements This text is saved along with data and parameter information in SPE and TSV files and it is used for the Peak Report and the Data Report The comments field saves a maximum of 50 characters Enter the desired text into the dialog box and click OK when finished Edit Iso Match Editing the Iso Match list Select the Edit menu and click Iso Match The following dialog box will be displayed Spectrum Techniques UCS 30 36 Isotope Match Edit JES Isotope Match Edit Bi sd Isotope Half Life Isotope Half Life 5 27 years Cd 109 1 27 years Cs 137 30 years Ba 133 10 4 years Mn 54 312 2 days Na 22 14 65 years Zn B5 244 1 days Add Delete EDIT Add Delete ED
168. riginal intensity by one half From Eq 8 In Iy ux 9 If 1 15 0 5 and x HVL In 0 5 4 HVL and hence 0 693 HVL 10 In this experiment we will measure u in lead for the 0 662 MeV gammas from Cs The accepted value is 0 105 cm g Values for other materials can be found in ref 8 Procedure 1 Place the Cs source about 5 0 cm from the Nal TI detector and accumulate the spectrum long enough for the sum under the 0 662 MeV peak Xc gt to be at least 6000 counts Determine Xc 2 2 Erase the MCA and insert a piece of lead from the ab sorber kit between the source and the detector Accumulate the spectrum for the same period of live time as in step 1 above Determine Zc 25 3 Erase the MCA and insert another piece of lead Deter mine Go X Repeat with additional thicknesses of lead until the count sum is 71000 Fill in the data in Table 3 3 Table 3 3 Data for Mass Absorption Coefficient Absorber Thickness mg cm WE EE RE T Fee EE Ke EC EEN WE E Ee ele EXERCISES a Using semilog graph paper plot vs absorber thickness in mg cm where Zc amp live time Determine the HVL from this curve and calculate u from Eq 10 How does your value compare with the accepted value of 0 105 cm g b Repeat the above experiment for the aluminum ab sorbers in the Absorber Kit The u for aluminum is 0 074 cm g EXPERIMENT 3
169. rs and spectrum data ROI data is reported by lower and upper channels set gross net FWHM centroid all channels and corresponding counts Display Calibration Display Calibration allows the user to switch between on off in calibration mode and channel numbers or energy is displayed on the horizontal line Display ROIs Display ROIs lets the user toggle between displaying and not displaying the ROIs Display Iso Match Display Iso Match lets the user toggle between displaying and not displaying the Iso Match peaks Spectrum Techniques UCS 30 38 Display Pixel Sizes Allows the user to choose between 1 2 and 3 pixels per data point displayed The default is 2 Spectrum Techniques UCS 30 39 Settings Clear ROI ID SSIUET SEIPGUIJEVIGE Settings ROIs Clicking on Clear ROI will clear the ROI indicated by the marker Allows the user to select the option to set or clear an ROI Clicking on Set ROI allows the user to set the ROI Spectrum Techniques UCS 30 40 Settings Energy Calibrate Energy Calibrate Opens a submenu for calibrating and uncalibrating the spectrum Settings Energy Uncalibrate Clicking Energy Uncalibrate will undo energy calibration and return the spectrum to the channel mode of data display Settings Energy Calibrate 2 Point Clicking 2 Point allows the user to calibrate the data using two points Settings Energy Calibrate 3 Point Clicking 3 Point allows the user to calibr
170. s PZ ADJ Screwdriver adjustable potentiometer to set the pole zero cancellation to compensate input decay times from 40 us to infinity BLR 3 position locking toggle switch selects the source of control for the gated baseline restorer discriminator threshold from Auto The BLR threshold is automatically set to an optimum level as a function of the signal noise by an internal circuit PZ Adj The BLR threshold is determined by the threshold potentiometer The BLR time constant is also greatly increased to facilitate pz adjustment this position may give the lowest noise for count rates under 5000 counts s and or longer shaping times Threshold The BLR threshold is manually set by the threshold potentiometer DC Screwdriver adjustable potentiometer to set the Unipolar Output dc level range 100 mV INPUTS BNC front and rear panel connectors accept either positive or negative pulses with rise times of 10 to 650 ns and decay times of 40 us to infinity Zi 1000 Q dc coupled linear maximum 10 V absolute maximum 20 V OUTPUTS UNI Front panel BNC connector with Z 1 Q and rear panel connector with Z 93 Q short circuit proof with full scale linear range of 0 to 10 V active filter shaped dc restored dc level adjustable to 100 mV BI Front panel BNC connector with Z 1 Q and rear panel connector with Z 93 Q short circuit proof prompt output with positive lobe leading and linear range of 10 V active filter s
171. s are not lost due to interactions with the scintillator see comments above Process other than weak decays that remove muons will result in a low value for z Random accidentals will be flat in time and will result in a high value for T unless you analyze your data properly The number of muon decays in the time interval from t and t is AN lt t gt N t N t Ny texp t x exp t T N sop At T exp lt t gt T where At t t and t t t 2 and the approximate relation is valid when At lt lt T Thus a histogram of the number of the observed decays AN t binned in time bins of width Af is predicted to be a simple exponential in lt f gt t A semi log plot of AN lt t gt versus t will have a slope 1 T Procedure The muon decay experiment starts with a large tank of liquid scintillator viewed by two phototubes PMTs If one PMT is sufficient to trigger on cosmic ray muons and on the electrons from muon decay why use two PMTs The basic setup is shown schematically in Fig 1 As depicted in Fig 1 the difference between a through going muon and a stopped muon followed by a f decay is one pulse versus two pulses 2 6 BASE PMT SCINTILLATOR MT BASE H a ELECTRONICS u e Fig 1 Schematic setup for muon lifetime experiment u passes through the scintillator losing some energy A single voltage pulse appears on the scope u stops in the scintillator and decays after time t
172. s live time then the data in the second file is divided by 2 200 seconds 100 seconds before it is subtracted Background Subtraction This is a special case of spectrum stripping Collect a background sample spectrum usually for a long collection time Load this spectrum as Background and click on Strip Background from Spectrum The live time fraction of the background is subtracted from spectrum This provides a convenient method of removing naturally occurring background from a sample spectrum and can be very useful when working with low level environmental samples Spectrum Techniques UCS 30 31 Load Spectrum ieee Strip Background View Help Load Spectrum Load Background how spectrum show Background Averiay Spectrur aid Backaround strip Background from Spectrum Click on Load Spectrum and in the File Dialog Box that opens select the spectrum you intend to have the background stripped from For example the spectrum may be taken for an isotope the background may be the readings with no isotope present Load Background StripBackground View Help Load Spectrum Load Background how spectrum show Backaround Click on Load background and in the File Dialog Box that opens select the background you intend to strip from the first For example Spectrum Techniques UCS 30 the spectrum may be taken for an isotope the background may be readings with no isotope present Show Spectrum
173. settings and the width of the coincidence time window Record the working parameters and do not adjust the PMT voltage Open the LabVIEW program Muon vi With appropriate timing settings and threshold parameters determined above this program records photon events collected by the PMTs Two measurements can be performed photon energy distribution and muon decay lifetime Energy distribution Select the measurement Energy and open the Coincidence tab The experiment can be done with a single PMT but more reliable data is obtained with simultaneous signals from two PMTs to verify the presence of a valid photon in the scintillator The goal of this measurement is to determine the approximate energy of each photon event by recording its time above threshold shown as T in the above figure The gate width can be set with the aid of the oscilloscope It should be long enough to capture the photon signal too long will introduce unnecessary noise Since the width of the triggering photon is of interest the gate minimum should be set to zero Only data from one of the PMTs decay detector will be recorded Start the program and wait 3 seconds for the card to initialize When the card is ready press the RUN button You will be prompted to specify the name and location of a data file where the 2 10 collected values of T in ns will be written Since data can be collected for an arbitrarily long time this file will auto save at a user specified interv
174. t panel test point providing a DC voltage ten 10 times the actual threshold setting Likewise each channel has a non updating regeneration circuit for adjustable output widths from 6 nSEC to 150 nSEC A unique summed output is common to all eight chan nels providing 1 mA of current for each activated channel thus allowing a fast decision to be made on the number of channels simultaneously hit Up to 16 channels can be OR D directly by cable to other summed outputs allowing a versatile scheme to form a trigger A fast veto input allows simultaneous inhibiting of all channels to reject unwanted events early in the system Similarly a bin gate will inhibit the entire module when applied via the rear connector The outputs are the current source type with one pair of negative bridged outputs and one complement for each channel When only one output of the bridged pair is used META a double amplitude NIM pulse 32mA is generated Snae when both connectors are used normal NIM levels 16 mA are produced The outputs have crisp clean transitions and their shapes are unaffected by the loading conditions of the other outputs INPUT CHARACTERISTICS General One LEMO connector input per channel 50 ohms 1 DC coupled less than 2 input reflection for a 2 0 nSEC input risetime Input protection clamps at 7 Volts and 5 Volts and can withstand 2 amps for 1 uSEC with no damage to the input Threshold
175. t to stop automatically after a ROI integral Click the Preset Integral Button on the toolbar SEIEGUISEVIGE Preset Time Preset Time x Real Time C Live Time Preset Live Time provides automatic correction for counting losses caused by the system deadtime or the amount of time required by the system to process pulses Events which occur during the pulse processing cycle are lost to the system so the timer is automatically updated to compensate for these losses When operating at excessively high count rates the deadtime meter will indicate a high value and the real counting time may be more than doubled Increasing the LLD setting can help reduce some high deadtime effects Preset Real Time sets the counting timer to run for actual clocktime and makes no correction for losses due to deadtime effects Click on Settings click on Presets Enter the LIVE or REAL time in the correct box Click on OK to set adjustment and exit menu HVv 650 ON LT 249 Unit 120 7 Pre Both the LIVE TIME and REAL TIME values are displayed on the UCS 30 status bar as LT and RT These values are saved in the file during data storage Spectrum Techniques UCS 30 23 ww w swrrrm 0 1 Preset Integral Set Integral To set an integral count it is necessary to first establish a ROI and then position the Preset E Es marker within the region Set integral count Selecting an ROI and setting a value other 1
176. table from 5 to 1250 Pulse Shape Semi Gaussian on all ranges with peaking time equal to 2 21 50 pulse width equal to 3 31 and pulse width at 0 1 level equal to 4 0 times the peaking time Bipolar crossover 1 5 Integral Nonlinearity For 1 5 us shaping time lt 0 05 Noise lt 5 uV rms referred to the input using 3 us unipolar shaping lt 7 HV using 1 5 us shaping both for a gain 3100 Temperature Instability Gain 0 0075 C 0 to 50 C DC Level 30 uV C 0 to 50 C Bipolar Crossover Walk 5 ns at 0 5 us for 50 1 dynamic range including contribution of an ORTEC Model 552 Single Channel Analyzer Overload Recovery Recovers to within 2 of rated output from X300 overload in 2 5 nonoverloaded pulse widths using maximum gain for unipolar output Same recovery from X500 overload for bipolar Restorer Gated active baseline stabilizer with automatic threshold circuit to provide the threshold level as a function of signal noise to the baseline restorer discriminator Spectrum Broadening Typically lt 10 FWHM for a Co 1 33 MeV gamma line at 85 of full scale for an incoming count rate of 1 000 to 50 000 counts s Unipolar output 1 5 us shaping Spectrum Shift Peak position shifts typically lt 0 02 for a 60co 1 33 MeV gamma line at 85 of full scale measured from 1 000 to 50 000 counts s Unipolar output 1 5 us shaping These count rate specifications were measured with a 10 HPGe detector Detectors
177. tereo 31 0201 000 Sys LabLaser 635nm 7mW E CW LabLaser 635nm 7mW Elliptical Beam 5 6 x 1 5mm CW Phono Plug Connector 19 22 mm dia x142 mm 7 56x15 02x07 990 yes ISys LabLaser 635nm 7mW E MVP LabLaser 635nm 7mW Elliptical Beam 5 6 x 1 5mm Modulation and Variable Power Control Let 55 mm dia x142 mm 7 Ee Wees goo Phono Phono Plug Connector Stereo 31 0300 000 Sys LabLaser 635nm 10mW E CW LabLaser 635nm 10 5mW Elliptical Beam 5 8 x 1 8mm CW Phono Plug Connector 19 22 mmdiaxt42mm 10 5 5 8x1 8 0 2x0 6 990 Roane Keeser Sys LabLaser 635nm 10mW E MVP LabLaser 635nm 10 5mW Elliptical Beam 5 8 x 1 8mm Modulation and Variable Power Controlo 55 mmdiaxia2mm 405 58x18 02x06 ogo Phono Phono Plug Connector Stereo 0221 164 00 Sys Indust 670nm 1mW 3mm C CW Industrial Laser Diode Module 670nm 0 95mW Circular Beam 3mm 19 22 mmdiaxi42mm 0 95 3 04 304 none 0221 699 02 Sys Indust 635nm 3mW C CW Industrial Laser Diode Module 635nm 2 9mW Circular Beam 1 1 mm 19 22 mmdiaxi42mm 29 141 07 304 none Phono 31 0128 000 Sys LabLaser 635nm 4mW C CW LabLaser 635nm 4 9mW Circular Beam 1 3mm CW Phono Plug Connector 19 22 mmdiaxi42mm 49 13 07 990 Geen nmm Sys LabLaser 635nm 4mW C MVP LabLaser 635nm 4 9mW Circular Beam 1 2mm Modulation and Variable Power Control Farde 22 mm diaxi42mm 49 12 08 ggo Phono Plug Connector Stereo 31 0144 000 Sys LabLaser ULN 635nm 5mW C LabLaser ULN Ultra Low Noise 0 05 RMS 635nm 5mW Circular
178. th a reasonably high quantum efficiency Lastly as you will see it is most straightforward to use a wavelength in the visible portion of the spectrum One could use an incandescent light bulb you might want to describe how this would be done after you have done this experiment but the most straightforward approach is to use a laser Our detector discussed in the next section will be a photomultiplier tube and for these the quantum efficiency increases as the photon wavelength decreases through the visible portion of the spectrum why is this So the relatively inexpensive red HeNe laser is fine but a green HeNe laser is even better Your laser is a Coherent 31 2264 000 serial No 9726EF a class IIIa laser with A 543 3nm and power of 0 3mW with a random polarization specifications in the Appendix 2 Light Tight Box As this experiment is about measuring single photons light present from other sources or scattered light from the laser itself can introduce significant errors Hence the 4 1 experiment is set up in a light tight box Length 36 Width 16 Depth 9 see Fig 1 As the PMTs dark current rises dramatically for 20 to 30 minutes following exposure to room light type intensities both PMTs are enclosed in a secondary box as shown in Figure 1 This makes it possible to make certain changes to the apparatus without exposing the PMTs to room light The box contains interlocks such that high voltage cannot be applied to
179. th the Start input signal Start Gate input signal must cross threshold 210 ns prior to the Start input signal and overlap the trigger edge of the signal Factory set in the positive input position STOP GATE Provides an external means of gating the Stop circuitry in either Coincidence or Anticoincidence with the Stop input signal Stop Gate input signal must cross threshold 210 ns prior to the Stop input signal and overlap the trigger edge of the signal Factory set in the positive input position OUTPUTS TAC Front and rear panel BNC connectors provide unipolar pulse Amplitude 0 to 10 V proportional to Start Stop input time difference Time End of delay period in Int Strobe mode prompt with Strobe input in Ext Strobe mode Width Adjustable by PWB potentiometer from 1 us to 3 us impedance Front panel Z 10 gt rear panel 93 Q Rise Time 250 ns Fall Time 250 ns VALID START Rear panel BNC connector provides NIM standard slow positive logic level signal Amplitude Nominally 5 V Complement sig nal selectable by PWB jumper Time and Width From accepted Start input to end of reset Impedance Z lt 10 Q Rise Time lt 50 ns Fall Time lt 50 ns VALID CONV Rear panel BNC connector provides NIM standard slow positive logic level signal to indicate a Valid Conversion Amplitude Nominaily 5 V Complement sig nai selectable by PWB jumper Time and Width From end of internal delay after Sto
180. the detector is only energy depend ent the standard and unknown sources do not have to be the same isotope It is only necessary that their gamma energies be approximately the same 10 in order to get a fairly good estimate of the absolute gamma activity of the unknown EXPERIMENT 3 6 Activity of a Gamma Emitter Absolute Method Purpose The activity of the standard used in Experiment 3 5 can be determined by the absolute method The purpose of this experiment is to outline the procedure for this method Here the source that is to be measured will be called U1 Procedure 1 Place the U1 source 9 3 cm away from the face of the detector 2 Accumulate a spectrum and note the live time that is used 3 Use the cursor to determine the sum under the photo peak zu Then erase the spectrum remove the source and accumulate background for the same live time and calculate Xb 4 Use the following formula to calculate the activity of U1 icu f Keng 7 activity of U1 Gef 7 Table 3 2 Gamma Decay Fraction f for Some Common Isotopes where t p live time in seconds intrinsic peak efficiency for the gamma energy and detector size used Fig 3 6 and ref 10 f the decay fraction of the unknown activity which is the fraction of the total disintegrations in which the measured gamma is emitted refs 7 and 8 and Table 3 2 G area of detector cm 47s source to detector distance
181. the number of counts you measure in a given time at a given point what you expect to see What sort of error appears in any spatial pattern observed To verify your experiment is in the single photon regime it is interesting to now investigate obtaining a single photoelectron pulse height spectrum from the PMT How many incident photons does it take to create one photoelectron PMTs employ multiple stages in order to achieve the gains necessary for the signal to be visible by other instruments In the first stage the photoelectron produced at the photocathode strikes the first dynode which produces some number 6 of secondary electrons These electrons then strike the second dynode which in turn produces electrons This is repeated at each of the PMT s N dynodes so the final electron signal leaving the PMT is 6 In general 6 increases as 4 3 some power gt 1 of the PMT voltage There are statistical fluctuations in 6 and in the simplest case on may assume these to be described by the Poisson distribution with a mean value of 6 and a standard deviation of 1 6 What would the standard deviation be for 2 photoelectrons What does this tell us about the distinguishing photon numbers as the number gets high How would you expect 6 to affect the spacing between energy levels What is the photon energy of the green laser light How much energy is needed to produce a single photoelectron Two photoelectrons For a single photoelectron
182. the output of the PMT should be an energy distribution with a peak How would the PMT output appear if one and two photoelectron events were present in the PMT Operating under conditions you used for the producing the interference pattern with single photons how does the output of the PMT appear if viewed using the MCA Can you distinguish different peaks If not try to increase or decrease the incident photon rate until you can see multiple peaks Use this to calibrate your MCA Which peak corresponds to what number of photoelectrons of photons Can you calculate 6 for a given PMT voltage Did you indeed accumulate your interference pattern with one photon at a time With the correct arrangement above we showed the quantum effect of single photon interference Assuming light actually appears as discrete quanta of light photons we insured there was only one in the box at a time however we did not actually show that these the light quanta passed through only one slit at a time If each light quantum passed through both slits then we would not need quantum mechanics to explain the phenomenon To prove that the light passed through only one slit at a time we ll divert the light passing through one slit to PMT 1 and the light passing through the other slit to PMT 2 To do this use the polarizing double slit you may want to look at the interference pattern produced by these slits using the unpolarizing slit assembly Put the polarizing assemble it
183. the second muon is indistinguishable from a decay electron This results in a random accidental signal that should be uniform in time and thus produce a flat background Start to think how you will analyze the data to accommodate this background D H TO TAC START START SIGNAL ies N V SE EE E TO TAC STOP STOP SIGNAL TIME u e I DELAY TIME pe I FIG 3 Sketch of the signals entering the TAC versus time not to scale in time The effect of the delay is to cut off the first part of the histogram stored in the MCA It does not change the exponential nature of the histogram Set the time window on the TAC to 5 10 muon lifetimes Thus the data at large times will be essentially all accidentals Don t set the time window too long or you will only be studying accidentals If you have time you should accumulate and analyze data taken with different TAC time windows To obtain adequate statistics you will need to run for at least 24 hours Remember to leave a big DANGER HIGH VOLTAGE sign on you apparatus The raw data from the MCA is a histogram of counts versus channel number You need to calibrate the system That is you supply a well defined time signal into the TAC MCA combination to obtain the conversion from channel number to time This is shown schematically in Fig 4 Use a pulse generator followed by a discriminator or simple splitter to create two in time signals Put one through a precision
184. thing ask the instructor or TA Safety topics include Machine Shop Safety Laser Safety High Voltage Safety and Radiation Safety Safety rules and guidelines are designed to reduce the possibility of accidents in routine situations In a research laboratory where much equipment is custom made there is no routine and there is no safety rule or policy that can substitute for an intelligent and careful handling of the equipment The following notes are intended to make you aware of the risks of working in the Senior and Optics Laboratories Machine Shop Safety Some basic directions are given in the lab write up Duplicate and additional items are listed below Never work alone in the shop Safety glasses must be worn in the shop at all times Do not enter the shop with bare feet sandals slippers or open toed shoes Tie back long hair Do not wear loose clothing or jewelry Maintain a clean work area Do not touch chips while the machine is operating Do not leave chuck keys in chucks Secure all work clamp in vice chuck etc Laser Safety For a complete introduction to laser safety see httos www osha gov SLTC laserhazards The American National Standard Institute ANSI has classified lasers according to what they perceive as hazard level Class Illb and class IV lasers are considered as hazardous The HeNe lasers used in the experiments you will be doing typically will not cause permanent eye damage howeve
185. to the detector element Then remove the paper and check that the reference beam is not deflected away from the detector if it is repeat the positioning steps When this procedure is completed translate the flow tube FT so that the beam intersection is in the middle of the tube Adjust the spectrum analyzer until a signal is found start by estimating the expected Doppler shift The true beat note signal will disappear when either of the beams is blocked Check to see that the frequency varies with the pump speed When you have found the beat note adjust the position of the various components to maximize the signal amplitude If the signal is sufficiently above the background gt 10 dB you will be able to take the necessary data by computer as with the slow wheel Take measurements at 1 mm intervals starting at one side and continuing until the other side is reached In analyzing your data plot the profile and qualitatively compare 5 6 it with what would be expected for a laminar flow look it up As usual discuss experimental problems error sources etc Note On occasion this experiment does not work out very well If such is the case for you at least obtain a measurement of the speed at the center of the tube and explain the problems encountered Summary of Procedures Upon completion of this experiment you should have sufficient data to obtain the following e The rotation rate of the slow wheel using the Doppler effect The sp
186. tput pulse will be extended if a new input pulse occurs while the output is active This provides deadtimeless operation and 10096 duty Cycle can be achieved impedance direct coupled less than 5 input reflection for a 1 nSEC risetime protected against damage 50 volt input transients Requires a 3 5 nSEC minimum input width in time with the input pulse leading edge to inhibit Bin Gate Rear panel slide switch enables or disables the slow bin gate via the rear connector Signal levels are in accordance with the TID 20893 standard GENERAL PERFORMANCE Functions Logic AND OR majority logic and logic fan in fan out All functions have leading edge inhibit with standard ized outputs Rate i 150 MHz minimum input to output Typically 160 MHz Double Pulse Resolution Less than 6 5 nSEC Typically 6 nSEC with output width set at minimum Input to Output Delay Less than 8 nSEC Multipie Pulsing One and only one output pulse regardless of input pulse amplitude or duration Power Supply Requirements 6 V 400 mA 6 V 250 mA 12 V 9 165 mA 12 V 0 mA 24 V 60 mA 24 V 35 mA 115 VAC 60 mA Note All currents within NIM specifications limits allowing a full powered bin to be operated without overioading Operating Temperature O C to 70 C ambient Packaging Standard single width NIM module in accordance with TID 20893 and Section 524 Options Call Phillips Scientific to find out about available optio
187. ttings for high voltage coarse and fine gain The screen is now energy calibrated from 0 to 1024 KeV Erase spectrum using the eraser icon Click the Go button and take a spectrum until you obtain a well defined peak at the 662 keV line of Cesium Stop the acquisition Set the ROI by clicking on Settings ROIs then Set ROI Place the cursor over the lower channel you wish to start the ROI with hold down the left mouse key and drag the cursor to the desired upper channel for the ROI Release the mouse button and the ROI will be set and highlighted When the cursor is placed anywhere in the ROI the total counts in the ROI will be displayed UCS 30 Quick Start Guide 4 E Spectrum Techniques UCS30 Live Mode E mE EZ EA ES PFH HOAT D Channel 30 gy Gross D ab Centroid Now set a preset count You can choose Time then Real Time or Live Time or Integral Counts Let s use Integral Counts since we have set a Region of Interest ROI Select Settings Presets then Integral Counts In the box enter a number for the desired level of counts in the ROI that will stop data acquisition Note You must first have your cursor set in your ROI Click on File and Save Setup enter a file name and save You can use this count protocol when ever you wish by selecting File Load Setup and selecting this file USING YOUR SYSTEM This guide is intended to help you setup and begin using your UCS 30 as quickly and easily as possi ble T
188. ual to Conversion Gain x Dwell Time Erase any current memory data and click START COUNTS The UCS 30 will proceed to count incoming events for the selected dwell time store the total in the first channel location reset the counter and repeat the cycle storing each total count in sequential channels Spectrum Techniques UCS 30 12 External Multi Channel Scaling trum Techniques UCS30 Mode If you wish to use an external pulse generation system such as a coincidence circuit it will be necessary to bypass the on board amplifier and discriminators Connect the external counts connector to the Ext MCS connector on the back of the instrument and select the menu item MODE then select External MCS When operating in this mode the MCS input requires positive TTL signals 22 5v 2150 ns duration Spectrum Techniques UCS 30 13 EE Mossbauer Internal ctrum Techniques UCS30 L This mode uses the internal preamp Connect the signal into the INPUT BNC connector The Mossbauer mode has variable dwell time ranging from 100 uSec to 6 Sec A Preset number of passes can be set to the desired number or left at zero 0 for infinite passes The following is the Mossbauer spectrum of a Co 57 source with an enriched Fe 57 absorber showing nuclear Zeeman splitting A Spectrum Techniques Channel 0 Counts 41951 Spectrum Techniques UCS 30 14 Mossbauer External trum Techniques UCS30 L
189. uffer offers excellent data throughput at high counting rates with minimal dead time losses Conversion gain may be changed from 4096 to either 2048 1024 512 or 256 channels via the software Data from the ADC is stored directly in on board memory for autonomy and high speed operation freeing the host computer for other tasks Software The UCS 30 produces a high resolution real time live color display of spectral data with standard PC graphics running under Windows 2000 and above Operation is intuitive using pull down menus and function buttons for the most commonly used commands and display options The software offers full control of all features including preset live real time and regions of interest together with centroid gross and net area calculations Control of the hardware amplifier high voltage ADC and input discriminators is also through function buttons for straightforward calibration and operation To simplify identification of Spectrum Techniques UCS 30 5 peaks the cursor may be calibrated to read directly in energy units using either a 2 point linear or 3 point quadratic relationship calibration to allow for detector non linearity Spectral files may be transferred to disk for long term storage as binary files or transferred through the clipboard in ASCII format for exporting to other programs Stored files may be used to collect background data over a long counting period that can be subtracted on a time proporti
190. umber of channels simultaneously hit Up to 16 channels can be OR D directly by cable to other summed outputs allowing a versatile scheme to form a trigger A fast veto input allows simultaneous inhibiting of all channels to reject unwanted events early in the system Similarly a bin gate will inhibit the entire module when applied via the rear connector The outputs are the current source type with one pair of negative bridged outputs and one complement for each channel When only one output of the bridged pair is used META a double amplitude NIM pulse 32mA is generated Snae when both connectors are used normal NIM levels 16 mA are produced The outputs have crisp clean transitions and their shapes are unaffected by the loading conditions of the other outputs INPUT CHARACTERISTICS General One LEMO connector input per channel 50 ohms 1 DC coupled less than 2 input reflection for a 2 0 nSEC input risetime Input protection clamps at 7 Volts and 5 Volts and can withstand 2 amps for 1 uSEC with no damage to the input Threshold 10 mV to 1 Volt 15 turn screwdriver ad justment better than O 296 C stability front panel test point provides a DC voltage ten 10 times the actual threshold setting Fast Veto One LEMO connector input common to all eight 8 channels accepts normal NIM level pulse 500 mV 50 ohms direct coupled must precede the negative edge of input pulse
191. urces is a problem analogous to the drunkard s walk Also the beauty of using spectrum analysis is that it measures the total amplitude of signals over only a small range of frequencies Thus the appropriate figure of merit is the ratio S N where S is the signal amplitude at a frequency of interest and N is the amplitude of the noises whose frequencies are within one resolution bandwidth of the signal Experimental Procedures This experiment is divided into three parts a Doppler shift measurement of the speed of a train and a rotating wheel b Transverse velocity measurement of the speed of a different wheel using scattering from a fringe pattern c Doppler shift measurement of the velocity profile of water flowing through a tube Figure 1 Experimental setup for the slow wheel Doppler Shift measurements L is the laser source BS is a beam splitter W is a motor driven wheel with reflective tape on its rim R is a reflector also tape covered and PD is the optical detector The electrical signal is sent to the 3585A spectrum analyzer SA for analysis and then to the computer C for recording The translation stage TS is provided for positioning the wheel 5 3 Doppler shift from a train and a rotating wheel The experimental setup for the wheel is sketched in Fig 1 Note the equivalence of this arrangement to a Michelson interferometer The beam from laser L is split by beam splitter BS and directed onto the edge of the slowly rotating
192. ut generated when the input signal falls below the lower level The ORTEC Model 550A Single Channel Analyzer is ideally suited for selecting a range of output pulse amplitudes from a spectroscopy amplifier for subsequent counting on a ratemeter or a JE counter timer It provides the excellent bee stability resolution and dynamic range WINDOW OR needed for measurements with high WE 4 resolution germanium and silicon WE detectors These same features provide more than adequate performance with scintillation counters proportional counters and ionization chambers The cover Leven entire instrument is dc coupled to ensure S C that the discriminator levels are not affected by changes in the counting rate even at very high counting rates The versatility of the Model 550A is enhanced by four basic operating modes In the INTEGRAL mode all input pulse amplitudes above the lower level produce an SCA output logic pulse This mode is useful for counting all pulses above the noise level or above a well defined lower amplitude limit The INTEGRAL mode can also be used for leading edge timing or pulse routing logic In the NORMAL mode the upper and lower level discriminators are independently variable over the full 20 mV to 10 V range The SCA output is generated only for pulse amplitudes that occur between the upper and lower levels This mode is useful when a wide range of pulse heights must be selected for counting
193. wheel W and reference reflector R both of which are covered with retroreflecting tape of the type used by runners bicyclists etc to avoid getting hit by cars This tape is composed of small beads embedded in a substrate with a matched refractive index such that light entering the bead is refracted to the back of the bead where it is internally reflected back toward the source This eliminates the need for the precise alignment required when flat mirrors are used The retroreflected beams are then recombined at the beamsplitter and continue to detector PD The electrical signal from PD is sent to a spectrum analyzer SA for measurement A spectrum analyzer HP 3585A is used to measure the beat frequency may be measured directly You can transfer the spectra to a computer see Appendix for instructions First calculate the expected Doppler shift from an estimate of the wheel rotation rate and set the analyzer accordingly Before connecting the detector signal to the spectrum analyzer look at it with an oscilloscope what is the amplitude of the signal and does its period correspond to your calculated estimate Measurements are to be made over a range of wheel positions at roughly one centimeter intervals for which translation stage TS is provided The range chosen should be such that one edge is accessible Note You must be sure that you are looking at the right peak on the spectrum analyzer trace Determine this by blocking either the reference o
194. with acoustic waves the apparent change in pitch of a passing siren demonstrating the Doppler effect optically is not a trivial matter The primary reasons for this are 1 Optical frequencies are much too high 10 Hz to be measured directly and 2 The shift corresponding to typical speeds is on the order of 0 1 10 MHz much less than the line width of a typical He Ne laser It is nonetheless possible to demonstrate the Doppler effect interferometrically using simple equipment In this experiment you will use a small He Ne laser an electronic spectrum analyzer a photodiode detector and some simple optical elements to measure the shift in frequency of light scattered from the back of a small moving train a rotating disk and from particles suspended in flowing water From this information you will be able to determine the velocity profile of the water flowing through a tube the speed of a train the speed of a disk and after directly measuring the disk speed the wavelength of the laser One disadvantage of the Doppler effect to measure speed is that you can only determine the velocity component along the line of sight It is possible to measure the transverse speed optically in spite of this handicap again interferometrically The trick is to project first an interference pattern onto the object then measure the frequency of the light fluctuations as it passes through the fringes The fringe spacing is determined from the geometry
195. y use brushes to remove metal chips from machines 6 Do not use compressed air to clean yourself or the machines 7 No earbuds iPods cell phone use or other portable device use 8 Don t invent your own techniques 9 Pay attention to your work and remain focused 10 No work in the shop while under the influence of drugs or alcohol This includes any prescription drugs which could cause drowsiness lightheadedness or disorientation have read and agree to abide to the above rules while in the machine shop understand that these rules are for the safety of ALL PERSONNEL in the shop Signature d SIN 133HS AWoS A3d ON DMG ON WOSA4 praje ALO LCEKLLE SOS IIIZ8 WN anbionbnqyy MIA d ViHalviN AN DA SPOT 6161 doys ounjovjy KurOUOIISV X sors Jo 1u ur11ed q Q3393H9 I AA gt MNVHO ONVH 430S OML sus 1 awevwuov QORIN MAN Rn Jo X LISUAAINN AHI 31va NMVHG G3AOtuddV diva NOILLdIHOS3G A3H 3NOZ SNOISIA3H visor LL 133HS ES v SLOS 1S q Aad OH 9MG ONWW9S4 3ZIS IN3Gf LS H3d ASSY V44 MAIA A18 N3SSV XNVHO GNVH H3Ql IS OML GL G L 31vq AlO LCEPLLE SOS IIIZ8 WN anbionbnqyy VigalviN AN DA Stulo 6161 doys ounjovjy tuouo 1sV X s ts tq Jo yuaurpredaq Q3 93H9 OOIXJW MAN JNOVAVHO V f x LISMAAINN AHJ NMVu
196. zation of the lasers should be orthogonal to each other Using a polarizing beamsplitter mJ PD PBS BS Reference BS beamsplitter PBS polarizing BS Source Figure 2 Wavemeter PBS the beams from the two lasers can be superimposed on each other and aligned through the wavemeter This allows the two beams to propagate the same optical path length through the same interferometer The beams are then separated at the exit of the interferometer and sent to two different photodetectors If necessary use color filters to further suppress the unwanted beam at the detectors We then can obtain data from two interferometers You will notice two practical problems with this arrangement 1 The translation axis of the variable arm has to be lined up with the beam with great accuracy 6 3 2 Due to diffraction it is difficult to observe uniform extinction and therefore good fringe contrast over the cross section of the beam Both problems can be alleviated by changing the beam waist of the Gaussian beam emitted by the He Ne laser Indeed the beam path in the long arm can be as much as 1 m longer than in the short arm In order to produce interference fringes with the best possible contrast the two beams must have the same intensity and therefore the same cross section This condition for a delay variation of 2 m implies some minimum dimension for the beam waist What is this minimum size Expand the beam with an

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