Model 467 Time to Pulse Height Converter and SCA
Contents
1. BIN MODULE CONNECTOR PIN ASSIGNMENTS NUCLEAR INSTRUMENT MODULES Function 3 volts 3 volts Spare Bus Reserved Bus Coaxial Coaxial Coaxiat 200 volts de Spare 6 volts 6 volts Reserved Bus Spare Spare Reserved 12 volts 12 volts Spare Bus Reserved Bus Spare Spare Reserved PER TID 20893 _ Pin 23 24 25 26 27 28 29 30 31 32 33 34 4835 36 37 38 39 40 41 142 Function Reserved Reserved Reserved Spare Spare 24 volts 24 volts Spare Bus Spare Spare 115 volts ac Hot Power Return Ground Reset iScaler Gate Ri Reset Auxiliary Coaxial Coaxial Coaxial 115 volts ac Neut High Quality Ground Ground Guide Pin Pins marked are installed and wired in ORTEC 401A and 4018 Modular System Bins Pins marked and are installed and wired in EGUG ORTEC HEP M250 N and M350 N NIMBINS2. The nomenclature used to identify the integrated circuit packages referred to in this manual is defined below for the example IC2 10 where IC integrated circuit 2 component number 10 pin number Any portion of an IC package can be designated by its output pin number 5 2 TPHC CIRCUIT The start input circuit contains D1 Q1 and resistors R1 through R4 which form a voltage limiter to protect the base input circuit of 02 A negative input signal of 250 mV or more limited at 700 mV is amplified by Q2 and Q3 and causes tunnel diode D3 to switch from its low state 50 mV to its high state 450 mv The tunnel diode remains in the high state until reset is furnished from Q51 to trigger D3 back to its low state While tunnel diode D3 is in its high state the current that normally flows through Q5 is switched to Q4 to perform two functions it drives the true start output circuit 05 06 1C1 and Q56 for an external timing signal keyed to an accepted and valid siart input and it switches the current that normally flows through Q12 to Q11 While current flows through Q11 Q10 is held at cutoff and a constant current from 046 charges the selected timing capacitor linearly the timing capacitor C6 and possibly C32 or C33 is selected by the Range Multiplier switch S2 If the X1 selection is changed to a X1000 selection C29 and C31 can also be selected as a part of the timing capacitor The voltage to which the s
3. CN6 drives the base of Q53 negative through Q55 The reset circuit forces D3 to its low state and clamps it until the external signal drops below approximately 3 5 V During this period a start signal will not be accepted l If SCA Inhibit switch S3 is set at In an SCA output signal is necessary in order to enable a strobed TPHC output With the switch in this position Q30 is normally saturated and blocks the gating signal at Q31 A positive SCA output signal SCA OK cuts off Q30 and allows the gating signal to propagate through Q31 to the gating circuit 6 MAINTENANCE G 6 1 TESTING PERFORMANCE The following test procedures are furnished as a guide during installation and checkout of the 467 TPHC SCA Test Equipment The following test equipment is recom mended Each test procedure refers to this list by the unit identification number for the required itemis of test equipment An equivalent unit may be substituted for any item in the list providing that it furnishes the function required for each specific application 1 Hewlett Packard 222A Pulse Generator 2 ORTEC 436 100 MHz Discriminator 3 ORTEC 416A Gate and Delay Generator 4 ORTEC 425 Nanosecond Delay 5 Photomultiplier tube with scintillator and radiation source 6 ORTEC 403A Time Pickoff Control 7 ORTEC 449 Log Lin Ratemeter 8 Tektronix Type 585 Oscilloscope 9 ORTEC 6240 Multichannel Analyzer 10 ORTEC 414A Fast Coincidence 11 ORTEC 444 Gated Bia
4. LINEAR OUTPUT SIGNAL CONNECTIONS AND TERMINATING IMPEDANCE The source impedance of the standard TPHC output with the 0 to 10 V linear range is about 19 through the connector on the front panel and 939 through the connector on the rear panel For the front panel circuit the interconnection to other modules does not usually require any special considera tions especially if the interconnecting cable is shorter than 4 ft in length Paralleling several loads on a single output will still not reduce the O to 10 V signal span significantly unless the combined load is less than 10092 The rear panel TPHC output circuit is designed for use of 930 cable to transfer the signals into a measuring circuit that has an input impedance of at least 100082 With this series impedance matched circuit connection there will usually not be any interference with the signal If oscilla tions should occur it will be necessary to provide an additional shunt termination of 10082 in parallel with the input circuit of the receiving instrument but this will result in about a 50 loss of signal amplitude As with any analog instrument oscillations may be ob served occasionally when unterminated lengths of cable are used Short cable lengths up to 4 ft need not be terminated When longer cabie lengths are required for transfer of a linear signal the cable should be terminated in a resistive load equal to the cable impedance to prevent reflections and oscil
5. SIGNAL CONNECTIONS The start and stop input circuits accept NIM standard fast negative pulses Each of these input circuits is designed with a 509 input impedance and is intended as the proper termination for the signals furnished through 502 cables Impedance considerations for each of the remaining logic inputs and output for the 467 are noncritical and 93N cable is usually used They can be terminated with 10082 to prevent ringing if the signal is used to drive a high impedance load 4 OPERATING INSTRUCTIONS TIME TO PULSE HEIGHT CONVERSION 4 1 There are seven front panel controls on the 467 Of these four are directiv associated with the conversion of a start to stop interval into an analog equivalent TPHC output pulse These controls are Range usec Multiplier TPHC Output Delay and Anti Coinc Coinc If the SCA Inhibit switch is set at In this also affects the generation of a TPHC output The Range psec and Multiplier switches determine the full scale limit for time conversion Any of 15 combinations may be selected as follows Switch Settings Full Scate Time Limit Range Multiptier 0 05 xi 50 ns 0 1 XI 100 ns 0 2 xi 200 ns 0 4 Xi 400 ns 0 05 X10 500 ns 0 8 Xi 800 ns 0 1 X10 Tus 0 2 X10 2 us 0 4 X10 4 us 0 05 X100 5 us 0 8 X10 8 us 0 1 X100 10 us 0 2 X100 20 us 0 4 X100 40 us 0 8 X100 80 us For example with the Range switch set at 0 05 and the Multiplier switch at X100 t
6. control the subsequent generation of a TPHC output if the front panel SCA inhibit switch is set at In Under this condition the SCA must generate an Output in order to permit the generation of a TPHC output at its strobe time and this can limit the range of time signals that are furnished to a multichannel analyzer to generate a spectrum An inde pendent SCA output signal is furnished through both the front and rear panel SCA Output BNC connectors for any external applications that may be desired A rear panal switch selects either Window or Normal mode for the SCA In the Window mode the acceptance range is from the LLD setting to the sum of the LLO plus ULD settings In tne Normal mode the LLD control and the ULD control each operates independently and the acceptance range is from the LLD setting to the ULD setting the ULD setting must always be greater than the LLD setting to generate an SCA output 5 CIRCUIT DESCRIPTION 5 1 GENERAL The circuits for the 467 are shown in schematics 467 0201 S1 and 467 0301 S1 and in block diagram 467 0101 81 All these drawings are included at the back of the manual The components that are included in schematic 467 0201 S1 all have reference designation numbers that are less than 300 and those on the 467 0301 S1 drawing have reference designations in the 300 series The division of circuits between the two boards on which the compo nents are mounted is indicated in the biock diagram
7. such as those in linear accelerator applications for example can be rejected by a Stop inhibit Mode switch and a circuit that is time adjustable from 0 1 to 1 0 us An inhibit reset circuit also permits the operator to abort and cancel a measurement after a true start has been recognized The input gate for the start circuit can be operated in either an anticoincidence or a coincidence mode Time ranges may be switch selected for full scale intervals from 50 ns to 80 us Each time measurement is analog stored in a low loss stretcher amplifier until a linear gate is opened by either an internal or an external strobe The internal strobe can be obtained from either the start or the stop input pulse and in either case occurs automatically at a selected delay following the reference An external strobe can be used for a prompt output at the strobe time provided that a time measurement has been compieted and reset has not occurred A rear panel switch can select either 5 or 120 us after stop for an automatic reset if no strobe has been furnished If reset occurs before a strobe no TPHC output signal is available There are two other sources for reset one occurs if the start to stop time interval exceeds the range that is selected and the other occurs as a result of an input pulse through the inhibit Reset Logic Input connector on the front panel The normal setting for the rear panel switch is 120 ps the 5 us setting should be used only if t
8. Model 467 Time to Pulse Height Converter and SCA Operating and Service Manual PHYSICS 111 LAB 286 Le Conte Hall T A FILE COPY NOT FOR LOAN Sh IND fa 74 0 3 80 Model 467 Time to Pulse Height e Converter and SCA Operating and Service Manual This manual applies to instruments marked Rev 21 on rear panel Y woe L Lev verb E A rd a ny r Ae hua Lira et Printed in U S A 2908 2 5C 0878 iii e CONTENTS Page WARRANTY kowt temi les haa ae Ae a tae AAA eae es Ree ea ae A oe Y PHOTOGRAPHS 0 0 ce ee eee rd tos e Arne 1 DESCRIPTION o eee ee Aa T E EE Wea BEE e dala EE 1 1 Purpose and Features dt e ts pole ie cara Me aah T Me Beara aes bs SI 1 2 Operation LL er eee tar nici amp feed Bock Sha AA 1 3 Logic A ACNE ARA E Lae a a SI 2 SPECIFICATIONS 0 ooo OR rele aa au Lea il 2 1 Performance RODE e Mn e E AZ 2 2 Controls CC ON A e se 8 2 3 Inputs ccc eee ee we o ASALTA Se Paneer E A a Pak ah Re a 3 ibi OUTPUtB ao doce e a ee a ea oe IRENE I Rs We tease A 3 2 5 Electrical and Mechanical te ee PA CD Lecce kite a 4 3 INSTALLATION o o EA AA LL 4 GOA NE ia a e ia a AB agg Me yer Aleta a A Fidi Connection ta Powar osea LE TI A E Aa 3 3 Connection into a System LL 4 e 3 4 Linear Output Signal Connections and Terminating Impedance 50000000zz 5 3 5 5 Logi
9. able output and the strobe signal is ignored lf the 467 is to be used as a stretcher or buffer storage of the analog output for more than 120 ys a simple modification can increase this time limit see Section 6 5 By the addition of four jumpers in the 467 circuit the X1 setting of the Multiplier switch can be replaced by a X1000 setting if these jumpers are added as described in Section 6 4 the minimum time range setting is 500 ns and the maximum range is 800 HS in any application of the 467 in which stop signals occur immediately following a true start but are to be ignored in favor of time measurements to stop signals that occur tater the rear panel Stop Inhibit circuit can be used With the Mode switch set at In the adjacent screwdriver control can be adjusted for a delay of 0 1 to 1 0 us and all stop signals are ignored that occur within the adjusted delay time following a true start signal The adjusted time delay can be monitored through the rear panel Monitor connector to measure the duration of the delay signal that occurs at each true start input time 4 2 SINGLE CHANNEL ANALYSIS The single channel analyzer portion of the 467 measures ihe peak amptitude of each analog TPHC pulse as soon as is formed if the peak amplitude is within the lower an uoper limits that are set with the LLD and ULD controls on the front panei an SCA output signal is generated after a 400 ns propagation time The signal can be used to
10. c Signal Connections ee 4 OPERATING INSTRUCTIONS o o o 1 S 4 1 Time to Pulse Height Conversion LL dae da ANA d ala eo a 5 4 2 Single Channel Analysis 2 i 6 5 CIRCUIT DESCRIPTION ic cd A ke e ee e en e l 7 5 1 General gi Si e e a A a a E a a A paa E Sidi TPAC CRONE il a A A ALIA eg ace 7 5 3 Single Channel Analyzer Circuit usasa 1 ee 8 GA Auxiliary Logia Dic e a AR A a a aa B a Re ge 8 6 MAINTENANCE is sa O fon E A A AT A una 9 6 1 Testing Performance o ura Ear a ia a a AA 9 6 2 Corrective Maintenance a ai ouo cso rasiau 0 4 0 4 0 9 e E 04 12 6 3 Troubleshooting ii ei aa a e e a ae i o A 14 6 4 Typical DC Voltages eel alam 4 4 4 0 2 4 4 e 0 15 6 9 Modifications a a e AA aa a RR Ae Ae duo e 15 6 6 Factory Repair aos sex a A a A a a a 15 Schematics and Block Diagram 467 0201 S1 e 467 0301 51 467 0101 81 vi SCA OUTPUT SCA MODE WINDOW STOP INHIBIT MODE DELAY MONITOR ORTEC 467 TIME TO PULSE HEIGHT CONVERTER AND SCA MANUAL 1 DESCRIPTION 1 1 PURPOSE AND FEATURES The ORTEC 467 Time to Pulse Height Converter and Single Channel A alyzer TPHC SCA measures the time interval between the leading edge of logic pulses furnished to its start and stop inputs and generates an analog output pulse that is proportional to the measured time through the TPHC output The TPHC output p
11. determine whether its peak amplitude is within the single channel acceptance range If the SCA responds it generates an SCA output that goes high about 600 ns after the leading edge of the true stop and this signal continues until the trailing edge of the subsequent reset If the SCA does not respond because the amplitude is either less than the LLO or greater than the ULD no SCA output is generated The front panel SCA inhibit switch determines whether the SCA response is essential in order to generate a TPHC output If the switch is set at In a TPHC output is generated only if the SCA has responded If the switch is set at Out the generation of the TPHC output is independ ent of the SCA response The TPHC output must be strobed The source of the strobe can be switch selected from the true start or true stop signal or from an external signal If true start is selected as the reference the strobe occurs after a fixed delay that is selected by the Multiplier switch so that it will accommodate the maximum range time if the switch is set at X1 the delay is 2 us for the X10 setting the delay is 10 us and for the X100 setting the delay is 100 us if true stop is selected as the reference the strobe occurs after a delay that has been adjusted with the front panel TPHC Output Delay control 1 to 10 us after the leading edge of the true stop signal If the Strobe Sync switch is set at Ext a signal must be furnished through th
12. e Strobe Ext BNC connector to strobe the output promptly The reset interval is 5 us and no output can be strobed after the teading edge of the reset pulse There should be no interference if the Strobe Reset switch is set at 120 us unless external strobe is being used and the strobe input pulse does not arrive within the interval before reset Reset can occur as the result of the completion of a read interval in which the TPHC signal is furnished as an output or of an overrange indication where no significant peak amplitude is available or of an inhibit reset input that cancels the cycle at its leading edge and inhibits further response by the 467 The principal purpose for the automatic reset is to furnish this function if external strobe is being used and the input pulse is not furnished If reset occurs for any reason before the TPHC output is completed the TPHC output width is reduced by the reset A busy output starts at the leading edge of the true start output and continues until the trailing edge of the subsequent reset This can be used to control external equipment by indicating each interval during which no new start input can be accepted 2 SPECIFICATIONS 2 1 PERFORMANCE Time to Pulse Height Converter Time Resolution lt 10 ps 10 11 s FWHM on 50 and 100 ns ranges lt 0 01 FWHM of full range for all other ranges Temperature Instability lt z10 ps C for 50 ns range lt 40 015 C for higher ranges 3 D
13. ector provides a positive 3 5 V pulse to indicate the time period during which stop signals are inhibited Rise Time lt 100 ns Output Width Variable from 100 ns to 21 0 us with Stop Inhibit Delay trim potentiometer beginning when a true start pulse is received Stop pulses are rejected until this pulse returns to the baseline if the Stop Inhibit Mode switch is in the in position Impedance 108 dc coupled 2 5 ELECTRICAL AND MECHANICAL Power Required 24 V 165 mA 24V 120 mA 12V 320 mA 12 V 140 mA Dimensions NIM standard double width module 2 70 in wide by 8 714 in high per TID 20893 3 INSTALLATION 3 1 GENERAL An ORTEC 401 402 Series Bin and Power Supply or equal in which the 467 will be installed is intended for rack mounting If vacuum tube equipment is operated in the same rack there must be sufficient cool air circulating to prevent localized heating of the all transistor circuits in the 467 and in the other modules in the Bin and Power Supply Rack mounted equipment subjected to the temper atures in vacuum tube equipment can exceed the maximum for which the transistorized circuits are designed unless this precaution is taken The 467 should not be subjected to temperatures in excess of 120 F 50 C 3 2 CONNECTION TO POWER The 467 is designed per TID 20893 and accepts its operating power requirements through a mating power connector when it is installed in an ORTEC 401 402 Series Bin and Po
14. elected timing capacitor can be charged is limited to 3 6 V by Q7 The voltage developed across the timing capacitor is applied to the input of a stretcher amplifier that includes 041 through Q44 This amplifier has a gain of unity and its output voltage is obtained from the gate of Q44B if a stop signal is not furnished within the selected time range Schmitt trigger Q53 and Q54 fires at a timing capacitor level of about 3 V from a 10 V signal on Q37E This identifies an overrange condition The output triggers the reset circuit which includes Q48 049 Q51 and Q52 The reset circuit causes tunnel dicde D3 to return to its low state without generating a TPHC output pulse if an external stop signal is received prior to the overrange identification Q46 is switched off and the timing capacitor receives no further charge The charge that accumulated on the timing capacitor between the start and stop input pulses determines the capacitor s voltage and therefore the output voltage In the stop input circuit diode D9 and its associated resistors form an amplitude limiting circuit similar to the start input circuit A valid start pulse enables the stop circuit through Q17 The stop pulse is amplified by 018 and 019 If the stop pulse arrives while 011 is enabled this diode is driven to its high state to switch the current from 021 through 020 When Q20 conducts Q45 is driven into conduction and the constant current through Q46 is cut of
15. ernal or external strobe Impedance lt 1 on front oanel and 938 on rear panel dc coupled Output dc Level Adjustable from 0 to 0 5 V de with front panel DC Adj screwdriver control SCA Outputs Front and rear panel BNC connectors 100 protected from short circuit and excessive duty cycle Amplitude 4 V on positive logic if TPHC pulse is in the LLD ULD window and O V if TPHC is not in the window Output Timing Pulse begins 600 ns after a valid stop pulse and continues until TPHC resets Impedance 108 dc coupled True Start Output Rear panel BNC connector provides a positive logic timing output to indicate the interval from an accepted start input signal until reset Rise Time lt 100 ns Output Width The interval from the start input until reset time which can occur at strobe time overrange or 120 us after stop signal Impedance lt 109 de coupled True Stop Output Rear panel BNC connector provides a positive 4 V pulse to indicate vatid stop and the interval from an accepted stop input signal until reset occurs Rise Time lt 100 ns Impedance 2108 de coupled U Output Width The interval from the stop input until reset time TPHC Busv Output Via rear panel BNC connector to indicate the total time that the 467 is inv lved in a conversion amplitude 4 V t lt 100 ns Z 109 dc coupled Output width is equal to the interval from the start input to 5 us after reset Stop Inhibit Monitor Rear panel BNC conn
16. f The selected timing capacity is not charged any further and has no discharge path so it holds the voltaje to which it has been charged Switching pair 021 and 020 also performs two additional functions If the internal stop strobe is used a trigger is furnished to the read timer Q24 and 027 through Q29 This circuit generates a delay of 1 to 1G us and then operates gate circuit 035 and O36 Switchirg pair Q21 and 020 also furnishes a strobe to the SCA circi it through 022 and Q23 Read timer Q27 and 028 performs two functions It opens linear gate Q36 and triggers reset througr 052 Timing for 027 and Q28 is adjusted by R86 and the gate width is normally set at about 2 us The linear ga e is opened during this period and reset occurs at the enci of the period At reset tunnel diode D3 is switched tc its low state and cannot be switched back to high again for about 5 ys this feature prevents pileup When D3 is reset it forces D11 to its low state through 04 012 and Q17 Linear gate Q36 conducts a current with an amplitude proportional to the charge stored n the timing capacity and the charge is proportional tc the time between start and stop input signals The gatiny pulse from Q33 causes Q35 to conduct to in turn cut off Q36 The current that was flowing through Q36 is rerouted into OA 1 during the period of the gating pulse OA is a high gain operational amplifier that has its gain regula ed to 1 for positive input si
17. gnals and to O for negative input signals The output from OA 1 drives another operational amplifier OA 2 on the 0301 board that has a gain of 1 and generates the positive TPHC output signals The TPHC information may be strobed out in three different ways The strobe pulse can be referenced inter nally to the stop signal internally to the start signal or externally In each case a 0 1e shot multivibrator is triggered to generate the gate pulse In the stop strobe mode R73 and R74 with C13 determine the time from the stop pulse until 024 conducts and the ne shot circuit is triggered The delay is adjusted from 1 to 10 us by R73 on the front panel In the start strohe mode the true start signal from IC1 12 triggers a one shot multivibrator that includes 1C3 6 C55 R189 and R191 The period of this one shot circuit is variable internally and determines the delay between the start pulse and the strobe pulse The start strobe signal drives the gate one shot that includes IC4 Q59 and Q26 In tre external strobe mode a positive pulse through the Strobe Ext input connector drives the gate one shot through Q26 Logic signals corresponding to true start true stop and TPHC busy are generated by the circuits that include IC1 1C2 056 057 nd Q58 If for any reason a strobe signal is not received the TPHC circuits are reset after Sor 120 us selected by 5 through Q33 and the overrange circuit by R103 C19 an i C22 For
18. h goss not affect the operation of the instrument Stop Inhibit Delay A 20 turn trim potentiometer mounted on the rear panel allows the stop inhibit period to be adjusted from 100 ns to 1 us after a true start pulse 2 3 INPUTS Start Input Front panel BNC connector Amplitude 250 mV minimum protected to 100 V Zin 509 decoupled Rise Time No limit but rise time should be as short as possible to provide maximum accuracy Pulse Width 3 ns at 250 mV maximum limit 4 us Stop Input Specifications same as for the Start input Gate Logic Input Front panel BNC connector Logic 0 lt 2 V logic 1 gt 2 V input protected to 100 V Gate signal must occur 10 ns before the start and must overlap the start input pulse Impedance 41 kQ dc coupled Inhibit Reset Logic Input Front panel BNC connector Amplitude of gt 4 V resets circuit at any point in the cycle and inhibits start pulses for the duration of the pulse input protected to 12 V Strobe Ext Rear panel BNC connector Amplitude gt 2 V protected to gt 25 V Rise Time No limit 7 Pulse Width 10 ns minimum 4 us maximum Impedance 1 kN decoupled Control Outputs Prompt with strobe input 2 4 OUTPUTS TPHC Outputs Front and rear panel BNC connectors 100 protected from short circuit and excessive duty cycle Unipotar O to 10 V linear lt 500 ns rise time Width Internally adjustable from 1 0 to 2 5 ps Output Timing Prompt with either int
19. he full scale time range is 5 us Any stop inout signal that occurs within 5 ps after a true start signal will initiate the gating of an output pulse through both TPHC Output connectors The output pulse will not be furnished through these connectors unless it is strobed The strobe condition is selected by a rear panel switch and can be based On the time of the true start signal delayed by an amount of time greater than the selected full scale time or by th stop signal delayed by an amount of time adjusted with the front panel TPHC Output Delay control or by an external strobe input signal When the output does occur its peak amplitude will be proportional to the ratio of the measured start to stop interval to the selected full scale time in a O to 10 V range Internal logic eliminates any pulse ambiguity No output pulse is furnished unless a stop signal is accepted within the selected full range time A stop signal is not effective unless it is preceded by a true start signal For further logical control either a coincidence or anticoincidence mode can be selected for gating control of the start input circuit To eliminate gating for the start input sei the Gate switch at Anti Coinc and leave the gate input circuit without any connection When the same switch setting is used and an input signal is furnished start signals are not accepted when the gate signal is 2 V or more For coincidence gating of the start input circuit set
20. he stop strobe mode is used and the delay is adjusted to minimum or if the external strobe mode is used and the strobe will be furnished within the selected interval The peak amplitude of the TPHC signal is sampled by the SCA at the time of a true stop input If the amplitude is within the adjusted acceptance range of the SCA an SCA logic output is generated The width of the SCA output is from the stop input until the subsequent reset Since this output occurs before the TPHC signal is used to generate ts analog output the SCA output can be used to inhibit a TPHC output unless the analog signal is within the SCA window and to thus limit the range of a timing spectrum as it is stored in the multichanne analyzer The single channel analyzer has a lower level discriminator that can be adjusted through the full linear range of th TPHC signals from 0 through 10 V The range for its upper level discriminator is also O through 10 V but the zero reference point for the ULD must be selected on the rear panel with the Window Normal switch When the switch is set at Window the zero reference for the ULD is the adjusted setting of the LLD control When the switch is set at Normat the zero reference for the ULD is ground zero and is equal to the LLD zero point 1 3 LOGIC An input can be accepted through the Start input connec tor on the front panel unless the 467 is busy processing a previous set of information or the response is inhibi
21. hen measure the time difference 7 from origin to response and furnish an output amplitude that is some fraction of the selected full scale amplitude proportional to the ratio of T to the selected full scale time range In any experiment in which the two count rates differ noticeably such as one in which fewer responses than event origins can be expected use the lower count rate as the start input to the 467 This assures that the 467 dead time will be minimized because it analyzes the time difference only after a start signal is accepted When the response is used as a start signal furnish the signals from the origin of events through a delay line into the stop input and adjust the delay to match the selected full scale time of the 467 At each start input signal the 467 will analyze the time until its related origin signal is furnished to the stop input The time measured is then delay time minus 7 and produces a so called inverted time spectrum The purpose for this type of system connection is to reduce the number of conversions and the corresponding dead time during the experiment For each signal accepted through the start input there must be a conversion but for each signal through the stop input there need not be a conversion For each start signal that is not followed by a stop signal within the selected time fuil range the converter measures a time equal to the total range even though no output pulse is generated 3 4
22. ifferential Nonlinearity lt 2 from 10 ns through fuli range for 50 ns range lt t2 from 5 range to full range for ali higher ranges Integral Nonlinearity lt 0 1 from 10 ns through full range for 50 ns range lt 0 1 from 5 range to full range for all higher ranges Single Channel Analyzer Temperature Instabilitv ULD lt 0 01 C LLD lt 0 01 C 6 Nonlinearity Effectively determined by the 10 turn poten tiometers ULD lt 0 5 over 10 V range LLD lt t0 5 over 10 V range 2 2 CONTROLS Range sec Switch selectable 15 range choices of 05 0 1 0 2 0 4 or 0 8 us multiplied by X1 X10 or X100 the X1 position can be internally modified to be X1000 to extend time range capability to 800 ps Multiplier Front panel 3 position selector switch settings select multiple factors for the selected time ranges of X1 X10 and X100 resulting in 15 time ranges from 50 ns to 80 us TPHC Output Delay Front panel 10 turn screwdriver potentiometer adjusts the output delay from the stop input to the internal stop strobe range lt 1 us to gt 10 us Anti Coinc Coinc Front panel slide switch selects either coincidence or anticoincidence logic for gating the start input circuit SCA ULD Front panel 10 turn potentiometer determines the window width or the upper level discriminator setting range O to 10 V SCA LLD Front panel 10 turn potentiometer adjustable from O to 10 V SCA Inhibit Front panel slide sw
23. itch In In this position the TPHC output pulse is available only if the output level falls within the SCA window Out in this position the switch has no effect on the TPHC output DC Adj 20 turn potentiometer to adjust the dc level over the range 0 5 V Strobe Sync Rear panel 3 position slide switch for select ing one of three modes Int Start In this position the information is strobed out 2 us after the start pulse when the Multiplier switch is in the X1 position 10 us in the X10 position and 100 us in the X100 position Ext In this position a positive pulse fed into the Strobe Ext connector will strobe the information to the output if the strobe pulse has a magnitude of 3 V or larger int Stop tn this position the information is strobed out 1 to 10 us adjustable by the TPHC Output Delay control after a true stop pulse Strobe Reset Rear panel 2 position switch that allows the converter to be reset either 5 us or 120 ps after a true stop pulse if a strobe pulse has not been received SCA Mode Rear panel 2 position stide switch Normal Allows independent use of upper level discrimi nator and lower level discriminator Window ULD setting is added to LLD setting when switch is in this position Stop Inhibit Mode Rear panel 2 position slide switch In Rejects stop pulses that occur within 100 ns to within 1 us adjustable by the Stop inhibit Delay control after a true start pulse Out in this position switc
24. lations in the cable Oscillation suppres sion can be effected by either a series termination at the sending end of the cable or by a shunt termination at the receiving end For convenience a BNC tee can usually accommodate both the cable and a mating terminator at the input of the receiving instrument These units are available commercially including BNC terminators with nominal values of 50 100 and 10002 ORTEC stocks a limited quantity of all but the 1000N terminators for your convenience as listed below BNC Tee Connector ORTEC C 29 502 Terminator ORTEC C 28 10082 Terminator ORTEC C 27 When a shunt termination at the receiving end of the cable is impractical consider series termination at the sending end For a series termination the full signal amplitude span is available at the receiving end only if the input impedance is many times the characteristic impedance of the cable For series termination install the correct resistance between the actual amplifier output on the etched circuit board and the output connector Effectively the terminating resistance is in series with the input impedance of the receiving instrument and may resuit in some loss in signal amplitude For example if the series terminator is 932 and the driven load is 9002 the available signal span will be only about 90 of the maximum signal amplitude for each pulse The termination of a 93Q cable in a 93Q load will cause a 50 loss for the signal 3 5 LOGIC
25. sed Amplifier Preliminary Procedures Take the following preliminary steps when the 467 is installed 1 Check the module visually for possible damage 2 With the power turned off install the 467 into a NIM standard Bin and Power Supply such as one of the ORTEC 401 402 Series 3 Check the installation for proper mechanical atignment 4 Switch on ac power and check the dc power voltage levels at test points on the 402 Power Supply control panel Basic Switch Settings Set the 467 controls as follows Range 0 05 us Multiplier 1 ULD 10 fully clockwise LLD 0 fully counterclockwise SCA Inhibit Out Logic input Anti Coinc Strobe Sync Int Stop SCA Mode Normai Strobe Reset 120 us Stop inhibit Mode Out Conversion Tests Use the typical test setup shown in Fig 6 1 and supply a start and stop pair of input signals with known time difference into the 467 Observe the TPHC output Then use the following procedures 1 Adjust the delay for the stop input to 25 or 30 ns more than the basic 13 ns required for a minimum response 2 Check to see that the full scale time range is 0 05 jus X 1 or 50 ns l PULSE GENERATOR m Neg Output FANOUT 12 0113 OSCILLO SCOPE 18 Stop Input jovitad Fig 6 1 Test System for Checking Conversion FOR AEC STANDARD 3 u a CeODINOMNDWN 2041 12 13 14 15 16 17 18 19 20 21 22 i SELE kem NIM BIN STD wiring
26. ted by a gate input condition The acceptance of a start input is essential in order to initiate a response in the 467 When a start input is accepted a positive logic signal is available through the rear panel True Start Output connector and is continued until the leading edge of a subsequent reset The reset can be caused by a TPHC output by the sensing of an overrange condition or by an inhibit reset signal through the front panel BNC The true start signal permits the internal circuits to start measuring a time interval and enables the stop input circuit The Stop input BNC can accept an input signal after it has been enabled by the true start condition It may be enabled immediately at true start or the rear panel Stop Inhibit Mode switch can be set at in and there will be a delay from true start before the stop signal can be accepted the delay range is 0 1 through 1 0 us When a stop input signal is accepted this indicates that an interval has been measured and its analog equivalent is stored and available A signal is furnished through the true stop output that continues until the leading edge of a subsequent reset If no stop input is accepted before an overrange condition is sensed or before an inhibit reset input is furnished the measurement will be aborted and no output signals for either SCA or TPHC will be generated At the true stop time the SCA is enabled to sample the peak amplitude of the stored timing signal and to
27. the Gate switch at Coinc and furnish a signal of 2 V or more through the Gate Logic Input connector when start signals are to be accepted If a signal is furnished through the tnhibit Reset connector on the front panel any time measurement that may be in process will be aborted and no new measurement can begin until the inhibit reset signal is removed To be effective the inhibit reset signal must precede an output strobe time The rear panel Strobe Sync switch selects the source for the strobe signal for the TPHC output When the switch is set at Int Start the strobe is generated by a delayed true start signal and the delay is fixed at a time that is longer than the selected full range time When the switch is set at Int Stop the strobe is generated by a delayed true stop signal and the delay is adjusted by the TPHC Output Delay control on the front panel within the range of 1 to 10 us When the switch is set at Ext an input pulse must be furnished through the adjacent BNC connector and the TPHC output signal is strobed promptly at the external signal time The timing of an external strobe input signal must be within the switch selected interval 5 or 120 ps after the true stop pulse for the measurement If the strobe is furnished prior to stop the signal is not accepted In the case of a strobe pulse failing to arrive within the selected interval after stop the 467 will have been automatically reset internally so there is no avail
28. this condition there is no TPHC output signal 5 3 SINGLE CHANNEL ANALYZER CIRCUIT There are two discriminator circuits in the SCA The lower level discriminator uses IC304 1C305 and 1C306 The upper level discriminator uses 1C301 1C302 and 1C303 Both channels obtain their reference voltage from 0301 and the maximum voltage at TP1 and TP2 is adjusted to 5 V with R301 and R316 The TPHC amplitude from Q37 is divided by R333 and A334 and 50 of the TPHC level is compared in 1C303 and 1C306 to their reference levels determined by the settings of R302 and R317 on the front panel and to the setting of rear panel SCA Mode switch S6 l A signal is obtained from the stop circuit through Q23 to trigger a one shot that includes IC308 R336 and C352 The output of the one shot is used to strobe the lower and upper comparators If the TPHC signal exceeds the lower reference but does not exceed the upper reference a positive logic output of 4 V is obtained at Q305 through 1C307 IC308 and IC309 if the TPHC signal is less than the lower reference or greater than the upper reference the gate circuits in 1C309 are not activated and there is no SCA output When switch S6 is set at Window the lower level and upper level reference voltages are summed at the input of 1C302 For this condition the window is the difference between the lower level adjustment and the sum of both the lower and upper level adjustments within the linear range limi
29. ts of the SCA 5 4 AUXILIARY LOGIC The 467 includes an input gate circuit a stop inhibit circuit an inhibit and reset circuit and an SCA inhibit circuit The function of each of these logic circuits is defined in Sections 4 1 and 4 2 The input gate circuit consists of D7 Q13 Q15 and Q16 When Gate switch S8 is set at Anti Coinc Q13 is saturated and a negative start input pulse can trigger tunnel diode D3 tf a positive gate input signal is furnished through CN2 Q15 conducts and clamps D3 to prevent it from respond ing With the Gate switch set at Coinc Q13 clamps D3 and prevents it from responding except when a positive input is furnished through CN2 Stop signals can be inhibited from triggering D11 through a controlled interval following each true start This function uses IC3 and IC4 The start signal triggers a one shot multivibrator that includes IC3 C56 R196 and R197 The output of 1C4 is normally high and is driven low during the period of the one shot If Stop Inhibit switch 7 is set at In the positive signal from 1C4 clamps Q17 through 016 to prevent response in D11 After 1C4 returns to low Q17 conducts and enables D11 to accept a stop input pulse A Positive monitor output is produced through 060 during the inhibit interval A signal through the Inhibit Reset connector on the front panel activates the overrange circuit Q53 and Q54 and resets the TPHC circuit at any time during a cycle A positive input through
30. ulses are appropriate for multichannel analysis to obtain timing spectra They are also connected internally to the single channel analyzer to generate an SCA output logic pulse for each TPHC pulse with a peak amplitude within the adjusted single channel limits There are 15 full scale time ranges that can be switch selected with the 467 from 50 ns through 80 ys Each TPHC output pulse has a peak amplitude that is propor tional to the ratio of the measured time interval to the selected full scale interval and the range of these pulses is O through 10 V The 467 is an extremely accurate and versatile instrument It is composed of a very stable gated time to pulse height converter a law droop stretcher a strobed TPHC output and a single channel analyzer that can be operated i in either a normal or window mode The integrated assembly in a NIM standard double width module combines excellent time resolution over a broad dynamic range with excellent temperature stability and linearity It is dc coupled throughout to prevent pileup and count rate distortion 1 2 OPERATION Start to stop time conversion is accomplished only after a valid start has been identified and after a stop pulse has arrived within the selected time range The start input is disabled during the busy interval to prohibit pileup the stop input is disabled after the first accepted stop signal Unwanted stop signals that occur immediately after a start input
31. wer Supply As a safety precaution always turn off the power for the Bin before inserting or removing any modules if all the modules installed in the Bin are ORTEC 400 and or 700 Series instruments there will be no overload on any portion of the Power Supply However if any modules not designed by ORTEC are included in the Bin this protection may not be effective monitor the de voltages at the test points on the control panel of the Bin after all modules have been installed and the power is turned on in order to determine that none of the four power levels have been reduced by an overload 3 3 CONNECTION INTO A SYSTEM The 467 can accept both start and stop pulses from discriminators that furnish NIM standard fast negative logic signals or from the timing output of a photomultiplier tube base Typical ORTEC instruments that provide compatible signals are the 416A 403A 473 and 260 discriminators and the 265 269 270 and 271 Photomultiplier Tube Bases The start and stop inputs will properly terminate 502 cable and this type is recommended to ensure proper termination of the signals No input or output connectors need be terminated when they are not in use in any experiment in which it is reasonable to assume that the count rates for start and stop will be equal or nearly so use the signal furnished from the origin of events into the start input and the signal furnished from the response into the stop input The 467 will t
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