Model 552 Pulse-Shape Analyzer and Timing Single
Contents
1. 24 V 90 mA 24 V 90 mA 12 V 190 mA 12 V 190 mA DIMENSIONS NIM standard single width module 1 35 by 8 714 inches per DOE ER 0457T 3 INSTALLATION 3 1 GENERAL The 552 must be used in conjunction with an ORTEC 4001 4002 Series Bin and Power Supply or equivalent which is intended for rack mounting If any source of heat is operating in the same rack there must be sufficient cooling air circulating to prevent any localized heating of the transistorized and integrated circuits used throughout the 552 The temperature of equipment mounted in racks can easily exceed the maximum unless precautions are taken the 552 should not be subjected to temperatures in excess of 120 F 50 C 3 2 CONNECTION TO POWER Turn off the Bin Power Supply when inserting or removing modules The ORTEC NIM modules are designed so that it is not possible to overload a properly operating power supply with a full complement of modules in the bin Since however this may not be true when the bin contains modules other than those of ORTEC design power supply voltages should be checked after the modules have been inserted The 4001 4002 has test points on the power supply control panel to monitor the dc voltage levels When using the 552 outside the 4001 4002 Bin and Power Supply be sure that the power extension cord or cable that is used properly accounts for the power supply grounding circuits that are provided according to the recommended2. of the peak amplitude 2 SPECIFICATIONS 2 1 PERFORMANCE INPUT DYNAMIC RANGE 200 1 PULSE PAIR RESOLVING TIME Output pulse width plus Delay selected by front panel Delay control or by external strobe input plus 200 ns for NIM standard fast negative output or plus 740 ns for NIM standard slow positive output Minimum resolving time for negative output 260 ns for positive output 800 ns THRESHOLD TEMPERATURE INSTABILITY lt 0 005 C of full scale 0 to 50 C DISCRIMINATOR NONLINEARITY lt 0 25 of full scale integral for each discriminator DELAY TEMPERATURE INSTABILITY lt 0 01 C of full scale 0 to 50 C measured at full scale DELAY NONLINEARITY lt 2 of delay range WINDOW WIDTH INCONSISTENCY lt 0 1 variation of full scale window width over the 0 to 10 V linear range MINIMUM INPUT THRESHOLD 40 mV TIME SHIFT vs PULSE HEIGHT Walk Specified for Channels A and B at 50 fraction Walk ps Input Dynamic Range System System 10 1 500 2000 50 1 1500 2500 100 1 2000 3000 200 1 2500 8000 Using the bipolar output of an ORTEC 460 Amplifier single delay line mode integrate lt 0 1 Us with delay line 1 Us Using an ORTEC 472A Amplifier unipolar output 0 5 Us shaping 2 2 CONTROLS UPPER LEVEL Front panel 10 turn potentiometer determines the window width 0 to 1 in the Window mode or the Upper Level 0 to 10 V in the Normal and Integral modes not used to
3. determine SCA outputs during Integral mode operation LOWER LEVEL Front panel 10 turn potentiometer adjustable from 40 mV to 10 V when the rear panel LL Ref switch is set for Int determines the threshold setting for the Lower Level discriminator when the LL Ref switch is set at Ext this control is ineffective MODE Front panel 3 position locking toggle switch selects one of three operating modes INT Integral LL sets a single discriminator threshold 40 mV to 10V and UL is not used to determine an SCA response NORM Normal UL and LL are independently adjustable levels UL range 0 to 10 V LL range 40 mV to 10V WIN Window LL sets the baseline level 40 mV to 10V and UL sets the window width LL to LL I V ATTN Front panel 3 position locking toggle switch selects an attenuation factor for the input signals X1 Input signals not attenuated X10 Input signals are attenuated by a factor of 1 10 X100 Input signals are attenuated by a factor of 1 100 DELAY Front panel 10 turn potentiometer for continuously adjustable delay for channel B output using internal strobe range 0 1 to 1 1 Us WALK ADJ A and B Independent front panel screwdriver adjustments on front panel for precise setting of walk compensation in each output channel The Walk Adj B control is ineffective when the B Fraction switch is set at its BI position LL REF MODE Rear panel 2 position locking toggle switch selects either the front panel LL co
4. input shaping and its time constants and of the expected dynamic range of operation Using a duplicate of the minimum and maximum amplitudes for shaped input pulses set each control to provide the minimum walk for its respective channel walk is the variation of time of occurrence vs input pulse amplitude Using internal strobe the decay shape of an input pulse can be reconstructed Use the following steps 1 Select the same fraction for both channels of outputs and adjust the Delay control as desired 2 Connect the channel A output to the Start input of a time to pulse height converter TPHC 3 Connect the channel B Neg output to the Stop input of the TPHC 4 Furnish the shaped input pulses to the 552 and measure the time difference between the channel A and channel B outputs This is an accurate measurement of the Delay time adjustment 5 Switch the B Fraction selector to each of its active settings 10 through 90 and measure the time differences at each level use the adjusted Delay time to correct each measurement Note Do not use the BI setting of the B Fraction selector unless the input pulse is bipolar since a zero crossover is necessary to obtain a channel B output when this selection has been made 6 Plot the decay curve for the input pulses using the set of data obtained in step 5 5 MAINTENANCE AND CALIBRATION 5 1 GENERAL The basic performance of the 552 Pulse Shape Analyzer and Timing SCA ca
5. 2 2 2 uv etse xe pd p ep pe ap 3 221 M 3 22V GO NRO as C Eee Ee DU DD A uu 3 2 INPUT SS peii A Emm 4 2A OUTPUTS sten RUN E E R EN EMEN 4 2 5 RELATED EQUIPMENT treten nette T te T ut el level ra 4 2 6 ELECTRICAL AND MECHANICAL 4 3 INSTALLATION ere ee eet iON A i tdt dud 5 GENERAL uss nas ne neh baa teed 5 3 2 CONNECTION TO POWER ek ey aaa ener certe cur e uhh e d e e 5 3 3 CONNECTION FROM LINEAR 5 3 4 5 cue vua ve qug UP gles 5 3 5 LOWER LEVEL REFERENCE INPUT 6 4 OPERATING INSTRUCTIONS DEDE EDEN 7 5 MAINTENANCE AND 22 8 bal GENERA yee 8 5 2 sO RE TCHER GALIBRATION Bie s s 8 5 3 WALK CALIBRATION rex UN UR UE ee ee a 8 5 4 LOWER EEVEL CALIBRATION cu etse ege ee 9 5 5 REPAIR t ertt MUN NEED NU HN EM 9 SAFETY INSTRUCTIONS AND SYMBOLS This manual contains up to three levels of safety instructions that must be observed in order to avoid perso
6. DOE standards outlined in DOE ER 0457T Both high quality and power return ground connections are provided to ensure proper reference voltage feedback into the power supply and these must be preserved in remote cable installations Be careful also to avoid ground loops when the module is operated outside the bin 3 3 CONNECTION FROM LINEAR AMPLIFIER The Input BNC connector on the front panel accepts positive unipolar or bipolar signals through a dc coupled input path For bipolar input pulses the positive lobe will be analyzed The amplifier output should be adjusted so that there is no dc offset and the pole zero networks are adjusted properly The input impedance of the 552 is 10000 When long cables are used to connect the amplifier output to the 552 Input cable termination may be necessary in order to prevent reflections match the cable impedance with a terminator at the 552 Input in such cases Normally the ATTN switch on the 552 front panel will be left at its X1 setting for operation in a system The main purpose for the X10 and X100 attenuator settings are to aid in precise walk adjustments 3 4 OUTPUT CONNECTIONS Outputs are furnished through both channel A and channel B connectors Each channel is considered separately because of the differences in timing characteristics of the two channels The channel A output on the front panel is dependent only on satisfaction of the input logic of the single channel analyze
7. Instruments not in warranty should follow the same procedure and ORTEC will provide a quotation Damage in Transit Shipments should be examined immediately upon receipt for evidence of external or concealed damage The carrier making delivery should be notified immediately of any such damage since the carrier is normally liable for damage in shipment Packing materials waybills and other such documentation should be preserved in order to establish claims After such notification to the carrier please notify ORTEC of the circumstances so that assistance can be provided in making damage claims and in providing replacement equipment if necessary Copyright 2002 Advanced Measurement Technology Inc All rights reserved is a registered trademark of Advanced Measurement Technology Inc All other trademarks used herein are the property of their respective owners CONTENTS ha SS a a ea ae ii SAFETY INSTRUCTIONS AND SYMBOLS 4 iv SAFETY WARNINGS AND CLEANING INSTRUCTIONS V 1 IDESCRIB ERE 1 TI PURPOSBEU S usu ud opt th pto pto uto a iets oh tp vt ppt ath a LN e t 1 T 2 EOWER EEVEL REFERENGE tata tte eta ed a ed he tt 2 1 3 OUTPUT STROBE aes ew ah el OR eee ree 2 1 4
8. Model 552 Pulse Shape Analyzer and Timing Single Channel Analyzer Operating and Service Manual Printed in U S A ORTEC Part No 733460 1202 Manual Revision F Advanced Measurement Technology Inc a k a ORTEC a subsidiary of AMETEK Inc WARRANTY ORTEC warrants that the items will be delivered free from defects in material or workmanship ORTEC makes no other warranties express or implied and specifically NO WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE ORTEC s exclusive liability is limited to repairing or replacing at ORTEC s option items found by ORTEC to be defective in workmanship or materials within one year from the date of delivery ORTEC s liability on any claim of any kind including negligence loss or damages arising out of connected with or from the performance or breach thereof or from the manufacture sale delivery resale repair or use of any item or services covered by this agreement or purchase order shall in no case exceed the price allocable to the item or service furnished or any part thereof that gives rise to the claim In the event ORTEC fails to manufacture or deliver items called for in this agreement or purchase order ORTEC s exclusive liability and buyer s exclusive remedy shall be release of the buyer from the obligation to pay the purchase price In no event shall ORTEC be liable for special or consequential damages Quality Control Before being approved for shipment e
9. ach ORTEC instrument must pass a stringent set of quality control tests designed to expose any flaws in materials or workmanship Permanent records of these tests are maintained for use in warranty repair and as a source of statistical information for design improvements Repair Service If it becomes necessary to return this instrument for repair it is essential that Customer Services be contacted in advance of its return so that a Return Authorization Number can be assigned to the unit Also ORTEC must be informed either in writing by telephone 865 482 4411 or by facsimile transmission 865 483 2133 of the nature of the fault of the instrument being returned and of the model serial and revision Rev on rear panel numbers Failure to do so may cause unnecessary delays in getting the unit repaired The ORTEC standard procedure requires that instruments returned for repair pass the same quality control tests that are used for new production instruments Instruments that are returned should be packed so that they will withstand normal transit handling and must be shipped PREPAID via Air Parcel Post or United Parcel Service to the designated ORTEC repair center The address label and the package should include the Return Authorization Number assigned Instruments being returned that are damaged in transit due to inadequate packing will be repaired at the sender s expense and it will be the sender s responsibility to make claim with the shipper
10. ber on the address label and on the package to ensure prompt attention when the shipment reaches the ORTEC factory 10 Bin Module Connector Pin Assignments For Standard Nuclear Instrument Modules per DOE ER 0457T 2 5 Function 3 V 3V Spare bus Reserved bus Coaxial Coaxial Coaxial 200 V dc Spare 6 V 6V 12 Reserved bus 13 Spare 14 Spare 15 Reserved 12 V 12V 18 Spare bus 19 Reserved bus 20 Spare 21 Spare 22 Reserved 41 Function Reserved Reserved Reserved Spare Spare 24 V 24V Spare bus Spare Spare 117 V ac hot Power return ground Reset Scaler Gate Reset Auxiliary Coaxial Coaxial Coaxial 117 V ac neutral High quality ground Ground guide pin Pins marked are installed and wired in ORTEC s 4001A and 4001C Modular System Bins
11. each channel 5 Switch the ATTN to X10 and check the response time for walk If any is noted adjust R86 carefully for channel A or R100 for channel B 6 Switch the ATTN to X100 and check for walk If necessary adjust R86 for channel A and R100 for channel B 7 Use all three settings of the ATTN switch and compare the timing responses The final adjustment of R86 and R100 should provide minimum walk The input attenuator is a high quality circuit for this application and contributes nominally less than 1 ns to the walk 8 Return the ATTN switch to X1 for normal operation 5 4 LOWER LEVEL CALIBRATION The minimum level to which the Lower Level front panel control can be set is 40 mV This can be calibrated by adjusting R54 on the printed circuit board as follows 1 Set the Lower Level control at 004 1000 dial divisions 2 Set the ATTN switch at X1 3 Furnish a 40 mV input pulse into the 552 4 Adjust R54 as required to half trigger under these conditions 5 5 FACTORY REPAIR This instrument can be returned to the ORTEC factory for service and repair at a nominal cost Our standard procedure for repair ensures the same quality control and checkout that are used for a new instrument Always contact Customer Services at ORTEC 865 482 4411 before sending in an instrument for repair to obtain shipping instructions and so that the required Return Authorization Number can be assigned to the unit Write this num
12. ions desired Each logic output for LL Out and UL Out is a NIM standard slow positive pulse that is compatible with ORTEC counters ratemeters and other instruments The output impedance through each output path is sufficiently low to drive as many as ten paralleled 10000 inputs 3 5 LOWER LEVEL REFERENCE INPUT If the LL Ref toggle switch on the rear panel of the 552 is set at Ext the reference level for the lower level discriminator must be furnished through the adjacent In BNC connector the 10 turn Lower Level control on the front panel is disconnected An input of 0 to 10 V through this connector corresponds directly to a range of 0 to 10 V for the lower level discriminator threshold The signal through the LL Ref In connector is not used unless the toggle switch is set at Ext 4 OPERATING INSTRUCTIONS After the 552 has been connected into a system according to the installation information in Section 3 the operating and strobe modes can be selected and the discriminator thresholds can be adjusted as required for each application Figure 4 1 illustrates the timing relationships that will be effective in the 552 operating with an internal strobe for each of three possible input pulse amplitudes The first two pulses exceed the lower level threshold without also exceeding the upper level and the third pulse exceeds both threshold levels Superimposed on each of these input pulses in Fig 4 1 are two internally stretched c
13. is intended for transmission to the driven unit through 50Q cable with 50Q termination The positive outputs can be furnished through 500 or 93Q cable to the driven unit A channel B output means that the logic for the channel A output has been satisfied and that an output strobe is furnished The output strobe can be generated internally or furnished from an external source depending on the setting of the rear panel switch The time when the channel B outputs are generated using the internal strobe is at a fixed delay after the trigger point on the decay of the input waveform The decay level is selected by a front panel switch that can be set at any multiple of 10 from 10 through 100 baseline crossover of a bipolar input referring to the decay from the peak amplitude of the pulse The range of the front panel Delay control is about 0 1 through 1 1 Us The channel B output time using an external strobe is promptly at the strobe pulse this strobe pulse must be furnished within 10 Us after the trigger point or the internal logic is reset without generating a channel B output Separate logic outputs are available through the rear panel to indicate when on the leading edge of an input pulse each of the two discriminators is triggered These responses can be used to monitor the discriminator levels during adjustment to be counted in external scalers to provide subgroup routing to a multichannel analyzer or for any other applicat
14. ll three operating modes 1 3 OUTPUT STROBE A rear panel toggle switch selects either an internal strobe based on a delayed trigger derived from the input signal or a strobe pulse that is furnished through the rear panel Strobe In connector to determine when the channel B outputs are to be generated This has no effect on the channel A output which is generated promptly at the constant fraction trigger When external strobe is used the input signal must be received within 10 us after the trigger time or the channel B outputs will not be generated When the internal strobe is used the Delay control on the front panel can be adjusted to set the delay time from the trigger point to the channel B output in the range of 0 1 through 1 1 Us 1 4 CONSTANT FRACTION TECHNIQUE Both output channels derive information that uses the constant fraction technique which is an ORTEC development It consists of comparing the amplitude along the decay of a pulse to a selected fraction of the peak amplitude of the same pulse Thus through a wide range of input pulse peak amplitudes the timing information is obtained with precision The reference fractions that are available in both output channels indicate the percentage of amplitude decay from the peak toward the ground reference level Thus a setting of 10 in either channel selects a trigger point at 90 of the peak amplitude for that channel or a setting of 20 selects a trigger point at 80
15. n be inferred from its operating responses 5 2 STRETCHER CALIBRATION There is a provision for calibration of the stretcher circuit Potentiometers R18 and R29 mounted on the printed circuit provide this calibration Use the following procedure 1 Remove jumper at location J1 from A to B and insert in B to C 2 Set potentiometer R18 fully counterclockwise as viewed from the top 3 With no input signals into the 552 adjust R27 to obtain O V 1 mV at TP1 4 Remove jumper at location JI from B to C and insert in A to B 5 With no input signals into the 552 adjust R18 to obtain O V 1 mV at TP1 Leave jumper in position A to B for normal operation 5 3 WALK CALIBRATION A Walk Adj control is furnished separately for each of the two output channels R86 serves channel A and R100 serves channel B Use the following procedure after the stretcher has been calibrated as described in Section 6 2 1 With the 552 turned on and with no input signal adjust R86 to a point where the dc levels at pins 3 and 4 of IC7 have a difference of 0 V Adjust R100 so the dc levels at pins 3 and 4 of IC9 have a difference of 0 V 2 Set the front panel ATTN switch at X1 the Mode switch at Int and use Internal Strobe Adjust the Lower Level control to its minimum setting 3 Furnish a 10 V shaped pulse into the 552 Input connector Use whatever shaping will be used for subsequent operation 4 Examine the response time for
16. nal injury and or damage to equipment or other property These are DANGER Indicates a hazard that could result in death or serious bodily harm if the safety instruction is not observed WARNING Indicates a hazard that could result in bodily harm if the safety instruction is not observed CAUTION Indicates a hazard that could result in property damage if the safety instruction is not observed Please read all safety instructions carefully and make sure you understand them fully before attempting to use this product In addition the following symbol may appear on the product ATTENTION Refer to Manual DANGER High Voltage Please read all safety instructions carefully and make sure you understand them fully before attempting to use this product SAFETY WARNINGS AND CLEANING INSTRUCTIONS DANGER Opening the cover of this instrument is likely to expose dangerous voltages Disconnect the instrument from all voltage sources while it is being opened WARNING Using this instrument in a manner not specified by the manufacturer may impair the protection provided by the instrument Cleaning Instructions To clean the instrument exterior Unplug the instrument from the ac power supply Remove loose dust on the outside of the instrument with a lint free cloth Remove remaining dirt with a lint free cloth dampened in a general purpose detergent and water solution Do not use abrasive cleaners CAUTION To preven
17. ntrol or the voltage signal applied to the rear panel LL Ref Ext connector for the lower level discriminator reference threshold STROBE MODE Rear panel 2 position locking toggle switch selects either an internal strobe derived from the input signal or an external strobe furnished through the adjacent connector to generate a channel B output The automatic reset time is 10 Us B FRACTION Front panel switch selects the constant fraction that will be used for the channel B response point marked 1 through 9 and BI for 10 through 90 and bipolar crossover 100 referring to the decay after the peak of the input waveform A FRACTION An internal jumper selects the constant fraction that will be used for the channel A response point jumper positions are 1096 2096 and 50 referring to the decay from the peak of the input waveform 2 3 INPUTS INPUT Front panel dc coupled BNC connector accepts positive unipolar or bipolar signals 0 to 10 V linear range 12 V maximum width gt 100 ns 1000Q input impedance LL REF IN Rear panel BNC accepts lower level bias when the LL Ref mode switch selects Ext An input of 0 to 10 V on this connector corresponds to a range of 0 to 10 V for the front panel Lower Level control Input protected to 24 V EXT STROBE IN Rear panel BNC accepts a NIM standard slow positive pulse nominally 5 V 500 ns wide to cause an output to occur from the channel B circuits when the Strobe switch i
18. onstant fraction reference levels the upper stretched level is at the 50 point on the input pulse decay which can be set in channel A the lower stretched level is at the 70 point on the input pulse decay which can be set in channel B When the input pulse decays through the 50 level the channel A CF discriminator is fired and triggers a prompt channel A output When the input pulse decays through the 70 level the channel B CF discriminator is fired and triggers an internal delay which then generates both negative and positive channel B outputs at the end of the delay The delay is front panel adjusted in the range of 0 1 through 1 1 Us If the 552 is set for Normal or Window mode time significant pulses would be generated for each of the first two input pulses but none would be generated for the third pulse because it is too large to satisfy the single channel criteria If the 552 is set for Integral mode the responses would be generated for the third input pulse as shown by the broken line output pulses For any mode of operation the LL Out and UL Out pulses are generated when the input pulse amplitude exceeds the related discriminator level The adjusted lower level threshold is furnished from either the front panel Lower Level control or an external source that is furnished through the rear panel LL Ref connector selection of the source is made with the rear panel LL Ref toggle switch In either case the range for an unatten
19. r and it occurs at the selected trigger level on the trailing edge of the linear input The channel B outputs are dependent on satisfaction of input logic and of a strobe which can be either internally generated or furnished from an external source The channel A output is available as a NIM standard fast negative pulse from a front panel BNC connector It is intended for transmission to the driven unit through 500 cable with 500 termination When the 552 is set for either the Normal or Window mode a channel A output means that an input pulse amplitude is sufficient to trigger the lower level discriminator without also triggering the upper level discriminator When the 552 is set for the Integral mode of operation the channel A output means that the input pulse amplitude is sufficient to trigger the lower level discriminator triggering of the upper level discriminator does not affect the output for this mode The time when a channel A output is made available is promptly at a trigger point on the decay of the input waveform The decay level is selected by an internal jumper on the printed circuit board which can be set for 10 20 or 50 referring to the decay from the peak amplitude of the pulse Three channel B outputs are available A NIM standard fast negative pulse is furnished through a front panel connector and a NIM standard slow positive pulse is furnished through both front and rear panel connectors The negative output
20. s set at Ext The external strobe must be provided within 10 Us after the linear input At the end of this period the 552 resets its internal logic without producing a channel B output 2 4 OUTPUTS SCA NEG OUT A Front panel BNC connector provides NIM standard fast negative output pulses from channel A only nominally 16 mA 800 mV on 500 load lt 20 ns wide lt 5 ns rise time Output occurs promptly at the channel A constant fraction trigger point SCA NEG OUT B Front panel BNC connector provides NIM standard fast negative output pulses from channel B only nominally 16 mA 800 mV on 500 load lt 20 ns wide lt 5 ns rise time Output occurs promptly at strobe time SCA POS OUT B Front and rear panel BNC connectors provide NIM standard slow positive output pulses from channel B only nominally 5 V 500 ns wide Output occurs promptly at strobe time 2 lt 100 LL OUT Rear panel BNC connector provides positive NIM standard output nominally 5 V 500 ns wide Output occurs as leading edge of the linear input crosses the LL threshold Z lt 10Q UL OUT Rear panel BNC connector provides positive NIM standard output nominally 5 V 500 ns wide Output occurs as leading edge of the linear input crosses the UL threshold Z lt 10Q 2 5 RELATED EQUIPMENT The 552 is compatible with all ORTEC amplifiers and other amplifiers having a 0 to 10 V linear output range 2 6 ELECTRICAL AND MECHANICAL POWER REQUIRED
21. t moisture inside of the instrument during external cleaning use only enough liquid to dampen the cloth or applicator Allow the instrument to dry completely before reconnecting it to the power source vi MODE NORM INT WIN B FRACTION ATIN De T INPUT i 1 i a pete Sr Ser Tors LL REF STROBE ds ORTEC MODEL 552 PULSE SHAPE ANALYZER AND TIMING SINGLE CHANNEL ANALYZER 1 DESCRIPTION 1 1 PURPOSE The ORTEC 552 PSA T SCA provides a versatile group of signal derivation functions It can be used as either a single channel analyzer or as an integral discriminator by comparing the time relationships between its two sets of outputs information can be interpreted for pulse shape analysis Each input signal that is accepted by the adjusted amplitude criteria generates two separate outputs each precisely time related to the input signal For reference in the instrument one output signal is generated through channel A and the other through channel B The input logic circuits can be used in any of three modes selected by a front panel switch The Integral mode uses the adjusted lower level discriminator as the only logic reference and generates an output if the input signal amplitude exceeds the lower level The Normal mode uses both lower level and upper level discriminators and generates an output if the input amplitude exceeds the lower level bias but does not e
22. ted after an adjusted delay following the constant fraction trigger point the delay is adjusted on the front panel within the range of 0 1 to 1 1 Us permitting normalization for specific applications When the rear panel switch selects external strobe the channel B outputs are generated promptly when a NIM standard positive strobe is furnished through the rear panel connector the strobe signal must be furnished within 10 Lis after the channel B constant fraction trigger point There are two channel B outputs one is a NIM standard fast negative pulse and the other is a NIM standard slow positive pulse By using an internally strobed channel B output the timing differentials between channels A and B can be used to measure the decay characteristics of an input pulse as the constant fraction points of the two channels are changed For example using a 5096 fraction for channel A and 1096 for channel B the time difference on the decaying waveform can be measured by subtracting the channel B delay In many applications the decay time of the pulse is significant for the type of particle that is detected so the pulse shape can be used to identify the nature of the source The 552 accepts either unipolar or bipolar input pulses having either RC or delay line pulse shaped waveforms It includes an input attenuator so that an input amplitude can be reduced by a factor of 1 10 or 100 selected by a front panel toggle switch The walk of the a
23. ttenuator is typically less than 1 ns This feature can be used to optimize the timing accuracy of both output channels The walk characteristics can be optimized individually in each channel using a front panel screwdriver adjustment for each channel When these controls are adjusted properly the walk characteristics for a bipolar delay line shaped input are less than 2 5 ns overa 200 1 dynamic range of input amplitudes see Fig 1 1 The instrument is designed to meet the interchangeability standards recommended by USDOE Report DOE ER 0457T An ORTEC 4001 4002 Series Bin and Power Supply provides all the necessary power through the rear panel module connector All signal levels and impedances are compatible with other ORTEC NIM modules 5521205 460 Amp Bipolar Output Tektronix Attenuator Channel B Walk ns Channel A 10 1 201 40 1 60 1 801 1001 200 1 Dynamic Range Fig 1 1 Typical Walk vs Dynamic Range 1 2 LOWER LEVEL REFERENCE A rear panel toggle switch selects either the front panel Lower Level control or the voltage signal furnished through the rear panel LL Ref connector as the reference for the lower level discriminator This permits flexibility in operation where an external reference source can furnish the lower level threshold from a stepped or sliding voltage source to automatically sweep the SCA response through a spectral range The selected source for the lower level reference is effective for a
24. uated input signal is from 0 to 10V measured from chassis ground The adjusted upper level threshold is determined by the setting of the front panel Upper Level control and by the mode selector toggle switch When the Fraction 70 p UL Out Channel A Qut Channel Trigger Delay gt Channel Neg Out Channel B Pos Qut Fig 4 1 Timing Relationships for Input and Output Pulses for Operation with Internal Strobe Switch is set at either Int or Norm the range of the variable control is from 0 to 10 V measured from chassis ground When the switch is set at Win the range of the variable control is 0 to 1 V measured above the adjusted lower level threshold When the rear panel Strobe switch selects Ext operation of the 552 is the same as it is for Int except for the time at which a channel B output is made available For this mode of operation an external strobe pulse must be furnished after the channel B CF trigger time and before an automatic reset and the channel B outputs are furnished promptly at the strobe time The time window during which the strobe can be effective is from the trigger time to 10Us after the trigger If no strobe is furnished within the time window the internal logic is reset without generating an output through channel B For optimum time significant outputs each front panel Walk Adj control must be trimmed for the combined effects of the
25. xceed the upper level the front panel Upper Level control is adjusted within a range of 0 to 10 V with ground as the zero reference point The Window mode operates the same as the Normal mode except that the zero reference point for the Upper Level control is equal to the adjusted lower level and the range of the Upper Level control is 0 to 1 V The lower level for any mode can be furnished from the front panel control or by a dc input signal through a rear panel connector An output signal through channel A is generated by the constant fraction method on the trailing edge of the input signal after the logic for acceptance has been completed The fraction is selectable at 1096 20 or 50 measured down from the peak pulse height using a jumper on the printed circuit board to select the fraction The output occurs promptly at the constant fraction point on the trailing edge and is a NIM standard fast negative output pulse with excellent timing characteristics An output signal through channel B is also generated by the constant fraction method on the trailing edge of the input signal The fraction for channel B is selected by a front panel switch that can be set for any level from 1096 through 10096 bipolar crossover in 1096 increments of the peak pulse height The unit must be strobed either internally or externally for an output pulse to be provided When the rear panel switch selects internal strobe the channel B outputs are genera
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