Model 575AAmplifier

Operating and Service Manual

Printed in U.S.A. ORTEC® Part No. 717460 1202Manual Revision C

Advanced Measurement Technology, Inc.

a/k/a/ ORTEC®, a subsidiary of AMETEK®, Inc.

WARRANTYORTEC* warrants that the items will be delivered free from defects in material or workmanship. ORTEC makesno other warranties, express or implied, and specifically NO WARRANTY OF MERCHANTABILITY ORFITNESS FOR A PARTICULAR PURPOSE.

ORTEC’s exclusive liability is limited to repairing or replacing at ORTEC’s option, items found by ORTEC tobe defective in workmanship or materials within one year from the date of delivery. ORTEC’s liability on anyclaim of any kind, including negligence, loss, or damages arising out of, connected with, or from the performanceor breach thereof, or from the manufacture, sale, delivery, resale, repair, or use of any item or services coveredby this agreement or purchase order, shall in no case exceed the price allocable to the item or service furnishedor any part thereof that gives rise to the claim. In the event ORTEC fails to manufacture or deliver items calledfor in this agreement or purchase order, ORTEC’s exclusive liability and buyer’s exclusive remedy shall be releaseof the buyer from the obligation to pay the purchase price. In no event shall ORTEC be liable for special orconsequential damages.

Quality ControlBefore being approved for shipment, each ORTEC instrument must pass a stringent set of quality control testsdesigned to expose any flaws in materials or workmanship. Permanent records of these tests are maintained foruse in warranty repair and as a source of statistical information for design improvements.

Repair ServiceIf it becomes necessary to return this instrument for repair, it is essential that Customer Services be contacted inadvance of its return so that a Return Authorization Number can be assigned to the unit. Also, ORTEC must beinformed, either in writing, by telephone [(865) 482-4411] or by facsimile transmission [(865) 483-2133], of thenature 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 standardprocedure requires that instruments returned for repair pass the same quality control tests that are used fornew-production instruments. Instruments that are returned should be packed so that they will withstand normaltransit handling and must be shipped PREPAID via Air Parcel Post or United Parcel Service to the designatedORTEC repair center. The address label and the package should include the Return Authorization Numberassigned. Instruments being returned that are damaged in transit due to inadequate packing will be repaired at thesender's expense, and it will be the sender's responsibility to make claim with the shipper. Instruments not inwarranty should follow the same procedure and ORTEC will provide a quotation.

Damage in TransitShipments should be examined immediately upon receipt for evidence of external or concealed damage. The carriermaking delivery should be notified immediately of any such damage, since the carrier is normally liable for damagein shipment. Packing materials, waybills, and other such documentation should be preserved in order to establishclaims. After such notification to the carrier, please notify ORTEC of the circumstances so that assistance can beprovided in making damage claims and in providing replacement equipment, if necessary.

Copyright © 2002, Advanced Measurement Technology, Inc. All rights reserved.

*ORTEC® is a registered trademark of Advanced Measurement Technology, Inc. All other trademarks usedherein are the property of their respective owners.

iii

CONTENTS

WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii

SAFETY INSTRUCTIONS AND SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv

SAFETY WARNINGS AND CLEANING INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

1. DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2. POLE-ZERO CANCELLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3. ACTIVE FILTER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2. SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.1. PERFORMANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.2. CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.3. INPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.4. OUTPUTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.5. RELATED EQUIPMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42.6. ELECTRICAL AND MECHANICAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3. INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.2. CONNECTION TO POWER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.3. CONNECTION TO PREAMPLIFIER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53.4. CONNECTION OF TEST PULSE GENERATOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.5. SHAPING CONSIDERATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63.6. LINEAR OUTPUT CONNECTIONS AND TERMINATING CONSIDERATIONS . . . . . . . . . . . . . . 63.7. SHORTING OR OVERLOADING THE AMPLIFIER OUTPUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4. OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.1. INITIAL TESTING AND OBSERVATION OF PULSE WAVEFORMS . . . . . . . . . . . . . . . . . . . . . . 74.2. FRONT PANEL CONTROLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.3. PANEL CONNECTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74.4. STANDARD SETUP PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.5. POLE-ZERO ADJUSTMENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84.6. OPERATION WITH SEMICONDUCTOR DETECTORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94.7. OPERATION IN SPECTROSCOPY SYSTEMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114.8. OTHER EXPERIMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

5. MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155.1. TEST EQUIPMENT REQUIRED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155.2. PULSER TEST* . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155.3. SUGGESTIONS FOR TROUBLESHOOTING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165.4. FACTORY REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165.5. TABULATED TEST POINT VOLTAGES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

iv

SAFETY INSTRUCTIONS AND SYMBOLS

This manual contains up to three levels of safety instructions that must be observed in order to avoidpersonal 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 isnot 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 notobserved.

Please read all safety instructions carefully and make sure you understand them fully before attempting touse 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 touse this product.

v

DANGER Opening the cover of this instrument is likely to expose dangerous voltages. Disconnect theinstrument from all voltage sources while it is being opened.

WARNING Using this instrument in a manner not specified by the manufacturer may impair theprotection provided by the instrument.

CAUTION To prevent moisture inside of the instrument during external cleaning, use only enough liquidto dampen the cloth or applicator.

SAFETY WARNINGS AND CLEANING INSTRUCTIONS

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.

! Allow the instrument to dry completely before reconnecting it to the power source.

vi

1

ORTEC MODEL 575A AMPLIFIER

1. DESCRIPTION

1.1. GENERALThe ORTEC 575A Amplifier is a single-width NIMmodule that features a versatile combination ofjumper-selectable pulse-shaping characteristics.The amplifier has extremely low noise, a wide gainrange, and excellent overload response foruniversal application in high-resolutionspectroscopy. It accepts input pulses of eitherpolarity. Input may originate from germanium orsilicon semiconductor detectors, from scintillationcounters with either fast or slow scintillators, fromproportional counters, from pulsed ionizationchambers, from electron multipliers, etc.

The unit has an input impedance of ~1000S andaccepts either positive or negative input pulses withrise times <650 ns and fall times >30 :s. Threeintegration and differentiation time constants arejumper-selectable on the printed wiring board(PWB) to provide optimum shaping for resolutionand count rate. The differentiation network hasvariable pole-zero cancellation that can be adjustedto match preamplifiers with decay times >30 :s.The pole-zero cancellation drastically reduces theundershoot after the differentiator and greatlyimproves overload and count rate characteristics. Inaddition, the amplifier contains an active, filter-shaping network that optimizes the signal-to-noiseratio and minimizes the overall resolving time.

The amplifier has unipolar and bipolar BNC outputs.The unipolar output is used for spectroscopy insystems where dc coupling can be maintained fromthe 575A to the analyzer. A BLR (baseline restorer)circuit is included in the unit for improvedperformance at all count rates. Baseline correctionis applied only during intervals between input pulsesand automatically selects a discriminator level toidentify input pulses. The unipolar output dc level iswithin the range of !5 mV to +5 mV. This outputpermits the use of the direct-coupled input of theanalyzer with a minimum amount of interfaceproblems.

The 575A can be used for constant-fraction timingwhen operated in conjunction with an ORTEC 551,552, or 553 Timing Single-Channel Analyzer. TheORTEC Timing Single-Channel Analyzers featurea minimum of walk as a function of pulse amplitude

and incorporate a variable delay time on the outputpulse to enable the timing pick-off output to beplaced in time coincidence with other signals.

The 575A has complete provisions, including powerdistribution, for operating any ORTEC solid-statepreamplifier. Normally, the preamplifier pulsesshould have a rise time of 0.25 :s or less toproperly match the amplifier filter network and adecay time >30 :s for proper pole-zerocancellation. The input impedance is 1000S.

When long preamplifier cables are used, the cablescan be terminated in series at the preamplifier endor in shunt at the amplifier end with the properresistors. The output impedance is ~0.2S, and theoutput can be connected to other equipment by asingle cable going to all equipment. The cable mustbe shunt-terminated at the far end. (See Section 3for further information).

1.2. POLE-ZERO CANCELLATIONPole-zero cancellation is a method for eliminatingpulse undershoot after the differentiating network.In an amplifier not using pole-zero cancellation(Fig. 1) the exponential tail on the preamplifieroutput signal (usually 50 to 500 :s) causes anundershoot whose peak amplitude is roughlydetermined from :

undershoot amplitude differentiated pulse amplitude

=differentiation time peramplifier pulse decay time

For a 1-:s differentiation time and a 50-:s pulse decay time the maximum undershoot is 2%, andthis decays with a 50-:s time constant. Underoverload conditions this undershoot is oftensufficiently large to saturate the amplifier during aconsiderable portion of the undershoot, causingexcessive dead time. This effect can be reduced byincreasing the preamplifier pulse decay time (whichgenerally reduces the counting rate capabilities ofthe preamplifier) or compensating for theundershoot by providing pole-zero cancellation.

2

Fig. 1. Differentiation in an Amplifier Without Pole-Zero Cancellation.

Fig. 2. Differentiation in a Pole-Zero Cancelled Amplifier.

Pole-zero cancellation is accomplished by thenetwork shown in Fig. 2. The pole [s + (1/To)] due tothe preamplifier pulse decay time is cancelled bythe zero of the network [s + (k/R2C1)]. In effect, the

dc path across the differentiation capacitor adds anattenuated replica of the preamplifier pulse to justcancel the negative undershoot of thedifferentiating network.

3

),()]/1([

1

)/1()( ∞→

+×

+= n

RCsRCs

ssG

n

Fig. 3. Pulse Shapes for Good Signal-to-Noise Ratios.

Total preamplifier-amplifier pole-zero cancellationrequires that the preamplifier output pulse decaytime be a single exponential decay and be matchedto the pole-zero cancellation network. The variablepole-zero cancellation network allows accuratecancellation for all preamplifiers having 30-:s orgreater decay times. Improper matching of the pole-zero network will degrade the overload performanceand cause excessive pileup distortion at mediumcounting rates. Improper matching causes either anundercompensation (undershoot is not eliminated)or an overcompensation (output after the mainpulse does not return to the baseline but decays tothe baseline with the preamplifier time constant).The pole-zero adjust is accessible on the frontpanel of the 575A and can easily be adjusted byobserving the baseline on an oscilloscope with amonoenergetic source or pulser having the samedecay time as the preamplifier under overloadconditions. The adjustment should be made so thatthe pulse returns to the baseline in the minimumtime with no undershoot.

1.3. ACTIVE FILTERWhen only FET gate current and drain thermalnoise are considered, the best signal-to-noise ratiooccurs when the two noise contributions are equalfor a given input pulse shape. The Gaussian pulseshape (Fig. 3) for this condition requires anamplifier with a single RC differentiation and nequal RC integrations where n approaches infinity.The Laplace transform of this transfer function is

where the first factor is the single differentiation,and the second factor is the n integrations. Theactive filter approximates this transfer function.

Figure 3 illustrates the results of pulse shaping in anamplifier. Of the four pulse shapes shown the cuspwould produce minimum noise, but this isimpractical to achieve with normal electroniccircuitry and would be difficult to measure with anADC. The true Gaussian shape deteriorates thesignal-to-noise ratio by only about 12% from that ofthe cusp and produces a signal that is easy tomeasure but requires many sections of integration(n64). With two sections of integration thewaveform identified as a Gaussian approximationcan be obtained, and this deteriorates the signal-to-noise ratio by about 22%. The ORTEC active filternetwork in the 575A provides a fourth waveform in

Fig. 3; this waveform has characteristics superior tothe n = 2 Gaussian approximation, yet obtains themwith two complex poles and a real pole. By thismethod, the output pulse shape has a good signal-to-noise ratio, is easy to measure, and yet requiresonly a practical amount of electronic circuitry toachieve the desired results.

4

2. SPECIFICATIONS

2.1. PERFORMANCEGAIN RANGE Continuously adjustable from 5 to1250.

PULSE SHAPE Semi-Gaussian on all ranges withpeaking time equal to 2.2J, 50% pulse width equalto 3.3J, and pulse width at 0.1% level equal to 4.0times the peaking time. Bipolar crossover = 1.5J.

INTEGRAL NONLINEARITY <±0.05% for 1.5-:sshaping time.

NOISE <5 :V rms referred to the input using 3 :sunipolar shaping; <7 :V using 1.5 :s shaping; bothfor a gain $100.

TEMPERATURE INSTABILITY Gain #±0.0075%/°C, 0 to 50°C.Dc Level #±30 :V/°C, 0 to 50°C.

WALK #±5 ns at 0.5 :s shaping for 50:1 dynamicrange, including contribution of an ORTEC 551 or552 Constant-Fraction Timing Single-ChannelAnalyzer.

OVERLOAD RECOVERY Recovers to within 2%of rated output from ×300 overload in 2.5nonoverload pulse widths using maximum gain forunipolar output. Same recovery from ×500 overloadfor bipolar.

RESTORER Gated active baseline stabilizer withautomatic threshold circuit to provide the thresholdlevel as a function of signal noise to the baselinerestorer discriminator.

SPECTRUM BROADENING* Typically <10%FWHM for a 60Co 1.33-MeV gamma line at 85% offull scale for an incoming count rate of 1 to 50k cps.Unipolar output, 1.5 :s shaping.

SPECTRUM SHIFT* Peak position shifts typically<0.02% for a 60Co 1.33-MeV gamma line at 85% offull scale (measured at the unipolar output, 1.5 :sshaping, 1 to 50k cps).

*These count rate specifications were measured with a 10% HPGe detector.Detectors with a large number of slow, rise-time signals will most likely give poorerresults.

2.2. CONTROLSFINE GAIN Ten-turn precision potentiometer withgraduated dial for continuously variable direct-reading gain factor of ×2.5 to ×12.5.

COARSE GAIN Six-position switch selectsfeedback resistors for gain factors of 2, 4, 10, 20,40, and 100.

SHAPING TIME Three-position printed wiringboard (PWB) jumpers, easily accessible throughside panel, select time constants for active pulse-shaping filter network of 0.5, 1.5, or 3 :s.

POS/NEG Toggle switch selects either Pos or Neginput pulse polarity.

PZ ADJ Screwdriver adjustable potentiometer toset the pole-zero cancellation to compensate inputdecay times from 30 :s to 4.

2.3. INPUTINPUT BNC (UG-1094A/U) front and rear panelconnectors accept either positive or negative pulseswith rise times of 10 to 650 ns and decay times of30 :s to 4; Zin = 1000S dc-coupled; linearmaximum 2 V; absolute maximum 20 V.

2.4. OUTPUTSUNI Front panel BNC connector with Zo <1S andrear panel connector with Zo = 93S. Short-circuitproof; full-scale linear range of 0 to +10 V; activefilter shaped; dc-restored with dc level adjustable to±25mV.

BI Front panel BNC connector with Zo < 1S andrear panel connector with Zo = 93S. Short-circuitproof; positive lobe leading and full-scale linearrange of 0 to +10 V; active filter shaped.

PREAMP POWER Rear panel standard ORTECpower connector (Amphenol 17-10090) mates withcaptive and noncaptive power cords on all ORTECpreamplifiers.

2.5. RELATED EQUIPMENTThe ORTEC 575A Amplifier accepts linear pulsesfrom, and furnishes power to, any standard ORTECpreamplifier or equivalent. Its output pulses may beused for linear signal analysis, using any of the

5

ORTEC modular instruments and multichannelanalyzers.

2.6. ELECTRICAL AND MECHANICALPOWER REQUIRED +24 V, 55 mA; !24 V, 40mA; +12 V, 70 mA; !12 V, 75 mA.

WEIGHTNet 1.5 kg (3.3 lb).Shipping 3.1 kg (7.0 lb.)

DIMENSIONS Standard single-width NIM module3.43 × 22.13 cm (1.35 × 8.714 in.) per TID-20893(Rev).

3. INSTALLATION

3.1. GENERALThe 575A operates on power that must be furnishedfrom a NIM-standard bin and power supply such asthe ORTEC 4001A/4002A Series. The bin andpower supply is designed for relay rack mounting.If the equipment is to be rack mounted, be sure thatthere is adequate ventilation to prevent anylocalized heating of the components used in the575A. The temperature of equipment mounted inracks can easily exceed the maximum limit of 50°Cunless precautions are taken.

3.2. CONNECTION TO POWERThe 575A contains no internal power supply andmust obtain the necessary dc operating power fromthe bin and power supply in which it is installed foroperation. Always turn off power for the powersupply before inserting or removing any modules.After all modules have been installed in the bin andany preamplifiers have also been connected to thePreamp Power connectors on the amplifiers, checkthe dc voltage levels from the power supply to seethat they are not overloaded. The ORTEC4001A/4002A Series Bins and Power Supplies haveconvenient test points on the power supply controlpanel to permit monitoring these dc levels. If anyone or more of the dc levels indicates an overload,some of the modules will need to be moved toanother bin to achieve operation.

3.3. CONNECTION TO PREAMPLIFIERThe preamplifier output signal is connected to the575A through the Input BNC connectors on the frontand rear panels. The input impedance is ~1000Sand is dc-coupled to ground; therefore, thepreamplifier output must be either ac-coupled orhave approximately zero dc voltage under no-signalconditions.

The 575A incorporates pole-zero cancellation toenhance the overload and count rate characteristicsof the amplifier. This technique requires matchingthe network to the preamplifier decay-time constantto achieve perfect compensation. The pole-zeroadjustment should be set each time the preamplifieror the shaping time constant of the amplifier ischanged. For details of the pole-zero adjustmentsee Section 4.5. An alternate method isaccomplished easily by using a monoenergeticsource and observing the amplifier baseline with anoscilloscope after each pulse under ~×2 overloadconditions. Adjustment should be made so that thepulse returns to the baseline in a minimum amountof time with no undershoot.

Preamplifier power at +24 V, !24 V, +12 V, and!12 V is available through the Preamp Powerconnector on the rear panel. When the preamplifieris connected, its power requirements are obtainedfrom the same bin and power supply as is used forthe amplifier, and this increases the dc loading oneach voltage level over and above therequirements for the unit at the module position inthe bin.

When the 575A is used with a remotely locatedpreamplif ier (i.e., preamplif ier-to-amplif ierconnection through 25 ft or more of coaxial cable),be careful to ensure that the characteristicimpedance of the transmission line from thepreamplifier output to the 575A input is matched.Because the input impedance of the 575A is~1000S, sending-end termination will normally bepreferred; the transmission line should be series-terminated at the preamplifier output. All ORTECpreamplifiers contain series terminations that areeither 93S or variable; coaxial cable type RG-62/Uor RG-71/U is recommended.

6

3.4. CONNECTION OF TEST PULSEGENERATOR

THROUGH A PREAMPLIFIER The satisfactoryconnection of a test pulse generator (such as theORTEC 419 Precision Pulse Generator orequivalent) depends primari ly on twoconsiderations: the preamplifier must be properlyconnected to the unit as discussed in Section 3.3,and the proper input signal simulation must beapplied to the preamplifier. To ensure proper inputsignal simulation, refer to the instruction manual forthe particular preamplifier being used.

DIRECTLY INTO THE 575A Since the input of the575A has 1000-S input impedance, the test pulsegenerator will normally have to be terminated at theamplifier input with an additional shunt resistor. Inaddition, if the test pulse generator has a dc offset,a large series isolating capacitor is also requiredbecause the 575A input is dc coupled. The ORTECtest pulse generators are designed for directconnection. When any one of these units is used, itshould be terminated with a 100-S terminator at theamplifier input or be used with at least one of theoutput attenuators set at In. (The small error due tothe finite input impedance of the amplifier cannormally be neglected.)

SPECIAL CONSIDERATIONS FOR POLE-ZEROCANCELLATION When a tail pulser is connecteddirectly to the amplifier input, the PZ ADJ should beadjusted if overload tests are to be made (othertests are not affected). See Section 4.5 for the pole-zero adjustment. If a preamplifier is used and a tailpulser is connected to the preamplifier test input,similar precautions are necessary. In this case theeffect of the pulser decay must be removed; that is,a step input should be simulated.

3.5. SHAPING CONSIDERATIONSThe shaping time constant on the 575A isselectable by PWB-mounted jumpers in steps of0.5, 1.5, and 3 :s. The choice of the proper shapingtime constant is generally a compromise betweenoperating at a shorter time constant foraccommodation of high counting rates andoperating with a longer time constant for a bettersignal-to-noise ratio. For scintillation counters, theenergy resolution depends largely on the scintillatorand photomultiplier, and therefore a shaping timeconstant of about four times the decay-timeconstant of the scintillator is a reasonable choice(for Nal, a 1.5!:s shaping time constant is aboutoptimum). For gas proportional counters, the

collection time is normally in the 0.5 to 5 :s rangeand a 1.5 :s or greater time constant selection willgenerally give optimum resolution. For surfacebarrier semiconductor detectors, a 0.5! to 2!:sresolving time will generally provide optimumresolution. Shaping time for Ge(Li) detectors willvary from 1.5 to 6 :s, depending on the size,configuration, and collection time of the specificdetector and preamplifier. When a charge-sensitivepreamplifier is used, the optimum shaping timeconstant to minimize the noise of a system can bedetermined by measuring the output noise of thesystem and dividing it by the system gain. The575A has almost constant gain for all shapingmodes; therefore, the optimum shaping can bedetermined by measuring the output noise with avoltmeter as each shaping time constant isselected.

3.6. LINEAR OUTPUT CONNECTIONSAND TERMINATING CONSIDERATIONS

Since the 575A unipolar output is normally used forspectroscopy, the unit is designed with the flexibilityto interface the pulse with an analyzer. A gatedbaseline restorer (BLR) circuit is included in thisoutput for improved performance at all count rates.The threshold for the restorer gate is determinedautomatically, according to the input noise level.The unipolar output dc level is 0 to ± 5 mV. Threegeneral methods of termination are used. Thesimplest of these is shunt termination at thereceiving end of the cable. A second method isseries termination at the sending end. The third is acombination of series and shunt termination, wherethe cable impedance is matched both in series atthe sending end and in shunt at the receiving end.The combination is most effective, but this reducesthe amount of signal strength at the receiving endto 50% of that which is available in the sendinginstrument.

To use shunt termination at the receiving end of thecable, connect the output from the 575A front orrear panels through 93-S cable to the input of thereceiving instrument. Then use a BNC teeconnector to attach both the interconnecting cableand a 100-S terminator at the input connector ofthe receiving instrument. Since the inputimpedance of the receiving instrument is normally1000S or more, the effective instrument inputimpedance with the 100-S terminator will be of theorder of 93S, and this will match the cableimpedance correctly.

7

oV

cpsRate

10000125max ×=

τ

Fig. 4. Typical Unipolar and Bipolar OutputWaveforms.

Fig. 5. Settings for Time-Constant Jumpers.

For customer convenience, ORTEC stocks theproper terminators and BNC tees, or they can beordered from a variety of commercial sources.

3.7. SHORTING OR OVERLOADING THEAMPLIFIER OUTPUT

The 575A output is dc-coupled with an outputimpedance of ~0.2S. If the output is shorted witha direct short circuit, the output stage will limit thepeak current of the output so that the amplifier will

not be harmed. When the amplifier is terminatedwith 100S, the maximum count rate consistent withlinear output is

where Vo is the peak output pulse amplitude in volts(V) and J is the shaping time in :s.

4. OPERATION

4.1. INITIAL TESTING AND OBSERVATIONOF PULSE WAVEFORMS

Refer to Section 5 for information on testingperformance and observing waveforms at frontpanel test points. Figure 4 shows typical outputwaveforms.

4.2. FRONT PANEL CONTROLSGAIN A Coarse Gain switch and a Gain control (aprecision 10-turn locking potentiometer) select andprecisely adjust the gain factor for the amplificationin the 575A. Switch settings are ×2, 4, 10, 20, 40,and 100. Continuous fine gain range is from ×0.5 to×12.5 using markings of 500 through 1250 dialdivisions.

Using these controls collectively, the gain can beset at any level from ×5 through ×1250.

POS/NEG A toggle switch selects an input circuitwhich accepts either polarity of pulses from thepreamplifier.

PZ ADJ A screwdriver control sets the pole-zerocancellation to match the preamplifier pulse decaycharacteristics. The range is from 30 :s to 4.

SHAPING PWB jumpers, easily accessed throughthe side panel, select equal integration anddifferentiation time constants to shape the inputpulses. Settings are 0.5, 1.5, and 3 :s. Illustrateddrawings and instructions for setting time-constantjumpers are shown in Fig. 5.

4.3. PANEL CONNECTORSINPUTS Accept input pulses to be shaped and/oramplified by the 575A. Compatible characteristics;positive or negative with rise time from 10 to 650 ns; decay time >30 :s for proper pole-zero

cancellation; input linear amplitude range 0 to 2 Vwith a maximum limit of ±20 V. Input impedance is~1000S.

8

Fig. 6. Typical Waveforms Illustrating Pole-ZeroAdjustment Effects; Oscilloscope Trigger,Internal Pos., 60Co Source with 1.33-MeV PeakAdjusted ~9 V; Count Rate 3 kHz; Shaping TimeConstant 1.5 :s.

OUTPUTSUNI Front panel BNC connector with Zo<1S andrear panel connector with Zo = 93S. Short-circuitproof; full-scale linear range of 0 to +10 V; activefilter shaped; dc-restored with dc level adjustable to±25 mV.

BI Front panel BNC connector with Zo < 1S andrear panel connector with Zo = 93S. Short-circuitproof; positive lobe leading and full-scale linearrange of 0 to +10 V; active filter shaped.

PREAMP POWER Rear panel standard ORTECpower connector (Amphenol 17-10090) mates withcaptive and noncaptive power cords on all ORTECpreamplifiers.

4.4. STANDARD SETUP PROCEDUREa. Connect the detector, preamplifier, high-voltage

power supply, and preamplifier into a basicsystem and connect the amplifier output to anoscilloscope. Connect the preamplifier powercable to the Preamp connector on the 575A rearpanel. Turn on power in the bin and powersupply and allow the electronics of the system towarm up and stabilize.

b. Set the 575A controls initially as follows:

Shaping 1.5 :sCoarse Gain 10Fine Gain 5.00Pos/Neg Match input pulse

polarity

c. Use a 60Co calibration source; place it about 25 cm from the active face of the detector. Theunipolar output pulse from the 575A should beabout 8 to 10 V using a preamplifier with aconversion gain (charge sensitivity) of170 mV/MeV.

d. Readjust the Gain control so that the higherpeak from the 60Co source (1.33 MeV) providesan amplifier output at ~9 V.

4.5. POLE-ZERO ADJUSTMENTThe pole-zero adjustment is extremely critical forgood performance at high count rates. Thisadjustment should be checked carefully for the bestpossible results.

USING A GERMANIUM SYSTEM AND 60Coa. Adjust the radiation source count rate beween

2 kHZ and 10 kHz.

b. Observe the unipolar output with anoscilloscope. Adjust the PZ ADJ control so thatthe pulse trailing edges return to the baselinewithout overshoot or undershoot (Fig. 6).

The oscilloscope used must be dc coupled andmust not contribute distortion in the observedwaveforms. Oscilloscopes such as Tektronix 453,454, 465, and 475 will overload for a 10-V signalwhen the vertical sensitivity is <100 mV/cm. Toprevent overloading the oscilloscope, use the clampcircuit shown in Fig. 7.

9

Fig. 7. A Clamp Circuit that can be used to PreventOverloading the Oscilloscope Input.

Fig. 8. Pole-Zero Adjustment Using a Square W tothe Preamplifier.

US I NG S Q UARE WAVE T HRO UG HPREAMPLIFIER TEST INPUTA more precise pole-zero adjustment in the 575Acan be obtained by using a square wave signal asthe input to the preamplifier. Many oscilloscopesinclude a calibration output on the front panel, andthis is a good source of square wave signals at afrequency of ~1 kHZ. The amplifier differentiatesthe signal from the preamplifier so that it generatesoutput signals of alternate polarities on the leadingand trailing edges of the square wave input signal,and these can be compared as shown in Fig. 8 toachieve excellent pole-zero cancellation. Use thefollowing procedure:

a. Remove all radioactive sources from the vicinityof the detector. Set up the system as for normaloperation, including detector bias.

b. Set the 575A controls as for normal operation;this includes gain, shaping, and input polarity.

c. Connect the source of 1-kHz square wavesthrough an attenuator to the Test input of thepreamplifier. Adjust the attenuator so that the575A output amplitude is ~9 V.

d. Observe the Unipolar output of the 575A with anoscilloscope. Adjust the PZ ADJ control forproper response according to Fig. 8. Use theclamp circuit in Fig. 7. to prevent overloadingthe oscilloscope input.

4.6. OPERATION WITH SEMICONDUCTORDETECTORS

CALIBRATION OF TEST PULSER An ORTEC419 Precision Pulse Generator (or equivalent) iseasily calibrated so that the maximum pulse heightdial reading (1000 divisions) is equivalent to 10-MeV loss in a silicon radiation detector. Theprocedure is as follows:

a. Connect the detector to be used to thespectrometer system; that is, preamplifier, mainamplifier, and biased amplifier.

b. Allow excitation from a source of known energy(e.g., alpha particles) to fall on the detector.

c. Adjust the amplifier gain and the bias level ofthe biased amplifier to give a suitable outputpulse.

10

o

dialrms

E

EEFWHMN

35.2)( =

Fig. 9. System for Measuring Amplifier and DetectorNoise Resolution.

Fig. 10. Noise as a Function of Bias Voltage.

d. Set the pulser Pulse Height control at theenergy of the alpha particles striking thedetector (e.g., set the dial at 547 divisions for a5.47-MeV alpha particle energy).

e. Turn on the pulser and use its Normalize controland attenuators to set the output due to thepulser for the same pulse height as the pulseobtained in step c. Lock the Normalize controland do not move it again until recalibration isrequired.

The pulser is now calibrated; the Pulse Height dialreads directly in MeV if the number of dial divisionsis divided by 100.

AMPLIFIER NOISE AND RESOLUTIONMEASUREMENTS As shown in Fig. 9, apreamplif ier, amplif ier, pulse generator,oscilloscope, and wide-band rms voltmeter such asthe Hewlett-Packard 3400A are required for thismeasurement. Connect a suitable capacitor to theinput to simulate the detector capacitance desired.To obtain the resolution spread due to amplifiernoise:

a. Measure the rms noise voltage (Erms) at theamplifier output.

b. Turn on the 419 precision pulse generator andadjust the pulser output to any convenientreadable voltage, Eo, as determined by theoscilloscope.

The full-width-half-maximum (FWHM) resolutionspread due to amplifier noise is then

where Edial is the pulser dial reading in MeV, and2.35 is the factor for rms to FWHM. For average-responding voltmeters such as the Hewlett-Packard400D, the measured noise must be multiplied by1.13 to calculate the rms noise.

The resolution spread will depend on the total inputcapacitance, because the capacitance degrades thesignal-to-noise ratio much faster than the noise.

D E T E C T O R N O I S E - R E S O L U T I O NMEASUREMENTS The measurement justdescribed can be made with a biased detectorinstead of the external capacitor that would be usedto simulate detector capacitance. The resolutionspread will be larger because the detectorc o n t r i b u t e s b o t h n o i s e a n d

capacitance to the input. The detector noise-resolution spread can be isolated from the amplifiernoise spread if the detector capacitance is known,since

(Ndet)2 + (Nelec)

2 = (Ntotal)2,

where Ntotal is the total resolution spread, and Nelec

is the electronic resolution spread when the detectoris replaced by its equivalent capacitance.

The detector noise tends to increase with biasvoltage, while the detector capacitance decreases.The net change in resolution spread will dependupon which effect is dominant. Figure 10 showscurves of typical noise-resolution spread versusbias voltage using data from several ORTEC siliconsurface-barrier semi-conductor radiation detectors.

A M P L I F I E R N O I S E - R E S O L U T I O NMEASUREMENTS USING MCA Probably themost convenient method of making resolutionmeasurements is with a pulse height analyzer, asshown by the setup illustrated in Fig. 11.

11

Fig. 11. System for Measuring Resolution with a PulseHeight Analyzer.

Fig. 12. System for Detector Current and VoltageMeasurements.

Fig. 13. Silicon Detector Back Current vs Bias Voltage.

The electronic noise-resolution spread can bemeasured directly with a pulse height analyzer andthe mercury pulser as follows:

a. Select the energy of interest with an ORTEC419 Precision Pulse Generator. Set the amplifierand biased amplifier gain and bias level controlsso that the energy is in a convenient channel ofthe analyzer.

b. Calibrate the analyzer in keV per channel, usingthe pulser; full scale on the pulser dial is 10MeV when calibrated as described above.

c. Obtain the amplifier noise-resolution spread bymeasuring the FWHM of the pulser peak in thespectrum.

The detector noise-resolution spread for a givendetector bias can be determined in the samemanner by connecting a detector to the preamplifierinput. The amplifier noise-resolution spread must besubtracted as described in “Detector Noise-Resolution Measurements.” The detector noise willvary with detector size and bias conditions andpossibly with ambient conditions.

CURRENT VOLTAGE MEASUREMENTS FOR SiAND Ge DETECTORS The amplifier system is notdirectly involved in semiconductor detector currentvoltage measurements, but the amplifier serves topermit noise monitoring during the setup. Thedetector noise measurement is a more sensitivemethod than a current measurement of determiningthe maximum detector voltage that should be usedbecause the noise increases more rapidly than thereverse current at the onset of detector breakdown.Make this measurement in the absence of a source.

Figure 12 shows the setup required for currentvoltage measurements. An ORTEC 428 BiasSupply is used as the voltage source. Bias voltageshould be applied slowly and reduced when noiseincreases rapidly as a function of applied bias.Figure 13 shows several typical current voltagecurves for ORTEC silicon surface-barrier detectors.When it is possible to float the microammeter at thedetector bias voltage, the method of detectorcurrent measurement shown by the dashed lines inFig. 12 is preferable. The detector is grounded as innormal operation, and the microammeter isconnected to the current monitoring jack on the 428detector bias supply.

12

Fig. 14. System for High-Resolution Alpha-ParticleSpectroscopy.

Fig. 15. System for High-Resolution GammaSpectroscopy.

4.7. OPERATION IN SPECTROSCOPYSYSTEMS

HIGH-RESOLUTION ALPHA-PARTICLESPECTROSCOPY SYSTEM The block diagram ofa high-resolution spectroscopy system formeasuring natural alpha particle radiation is shownin Fig. 14. Since natural alpha radiation occurs onlyabove several MeV, an ORTEC 444 BiasedAmplifier is used to suppress the unused portion ofthe spectrum; the same result can be obtained byusing digital suppression on the MCA in manycases. Alpha-particle resolution is obtained in thefollowing manner:

a. Use appropriate amplifier gain and minimumbiased amplifier gain and bias level.Accumulate the alpha peak in the MCA.

b. Slowly increase the bias level and biasedamplifier gain until the alpha peak is spreadover 5 to 10 channels and the minimum- tomaximum-energy range desired corresponds tothe first and last channels of the MCA.

c. Calibrate the analyzer in keV per channel usingthe pulser and the known energy of the alphapeak (see “Calibration of Test Pulser”) or twoknown-energy alpha peaks.

d. Calculate the resolution by measuring thenumber of channels at the FWHM level in thepeak and converting this to keV.

HIGH-RESOLUTION GAMMA SPECTROSCOPYSYSTEM A high-resolution gamma spectroscopysystem block diagram is shown in Fig. 15. Althougha biased amplifier is not shown (an analyzer withmore channels being preferred), it can be used ifthe only analyzer available has fewer channels andonly higher energies are of interest.

When a germanium detector that is cooled by aliquid nitrogen cryostat is used, it is possible to

obtain resolutions from about 1 keV FWHM up(depending on the energy of the incident radiationand the size and quality of the detector).

Reasonable care is required to obtain such results.Some guidelines for obtaining optimum resolutionare:a. Keep interconnection capacitance between the

detector and preamplifier to an absoluteminimum (no long cables).

b. Keep humidity low near the detector-preamplifier junction.

c. Operate the amplifier with the shaping time thatprovides the best signal-to-noise ratio.

d. Operate at the highest allowable detector biasto keep the input capacitance low.

S C I N T I L L AT I O N - C O U N T E R G AM M ASPECTROSCOPY SYSTEMS The ORTEC 575Acan be used in scintillation-counter spectroscopysystems as shown in Fig. 16. The amplifier shapingtime constants should be selected in the region of0.5 to 1.5 :s for Nal or plastic scintillators. Forscintillators having longer decay times, longer timeconstants should be selected.

13

Fig. 16. Scintillation-Counter Gamma SpectroscopySystem.

Fig. 18. Gamma-Ray Charged-Particle Coincidence Experiment.

Fig. 17. High-Resolution X-Ray Energy Analysis SystemUsing a Proportional Counter.

X - R A Y S P E C T R O S C O P Y U S I N GPROPORTIONAL COUNTERS Space chargeeffects in proportional counters, operated at highgas amplification, tend to degrade the resolutioncapabilities drastically at x-ray energies, even atrelatively low counting rates. By using a high-gain,low-noise amplifying system and lower gasamplification, these effects can be reduced and aconsiderable improvement in resolution can beobtained.

The block diagram in Fig. 17 shows a system of thistype. Analysis can be accomplished bysimultaneous acquisition of all data on amultichannel analyzer or counting a region ofinterest in a single-channel analyzer window with acounter and timer or counting ratemeter.

4.8. OTHER EXPERIMENTS

Block diagrams illustrating how the 575A and otherORTEC modules can be used for experimentalsetups for various other applications are shown inFigs. 18, 19, and 20.

14

Fig. 19. Gamma-Ray Pair Spectrometry.

Fig. 20. Gamma-Gamma Coincidence Experiment.

15

Fig. 21. Circuit Used to Measure Nonlinearity.

5. MAINTENANCE

5.1. TEST EQUIPMENT REQUIREDThe following test equipment should be used toadequately test the specifications of the 575Aamplifier:

1. ORTEC 419 Precision Pulse Generator or 448Research Pulser.

2. Tektronix 547 Series Oscilloscope with a type1A1 plug-in or equivalent.

3. Hewlett-Packard 3400A rms voltmeter.

5.2. PULSER TEST*FUNCTIONAL CHECKS Set the 575A controls asfollows:

Coarse Gain 100Gain 7.5Input Polarity NegShaping Time Constant 1.5 :s

a. Connect a positive pulser output to the 575Ainput and adjust the pulser to obtain +10V at theunipolar output. This should require an inputpulse of 13.3 mV using a 100-S terminator atthe input. Adjust PZ if necessary.

b. Change the input polarity switch to Pos andthen back to Neg while monitoring the output fora polarity inversion.

c. Monitor the bipolar output for dc level of<±5 mV; pulse shape should be bipolar. Returnto UNI.

d. Recheck the output pulse amplitude and adjustif necessary to set it at +10 V with maximumgain. Decrease the Coarse Gain switch stepwisefrom 100 to 2 and ensure that the outputamplitude changes by the appropriate amountfor each step. Return the Coarse Gain switch to100.

e. Decrease the Gain control from 7.5 to 2.5 andcheck to see that the output amplitudedecreases by a factor of 2. Return the Gaincontrol to maximum at 7.5.

f. With the shaping jumpers set for 1.5 :smeasure the time to the peak on the unipolaroutput pulse; this should be 3.3 :s (or 2.2J).

*See IEEE Standards No. 301-1976.

Measure the time to baseline crossover of thebipolar output; this should be 5.0 :s (or 3.3J).

g. Change the shaping jumpers to 0.5 and 3 :s inturn. At each setting, check to see that the timeto the unipolar peak is 2.2J. Return the jumpersto 1.5 :s.

OVERLOAD TESTS Start with maximum gain,J = 1.5 :s, and a +10 V output amplitude. Increasethe pulser output amplitude by ×200 and observethat the unipolar output returns to within 200 mV ofthe baseline within 24 :s after the application of asingle pulse from the pulser. It will probably benecessary to vary the PZ ADJ control on the frontpanel in order to cancel the pulser pole andminimize the time required for return to thebaseline.

16

LINEARITY The integral nonlinearity of the 575Acan be measured by the technique shown in Fig. 21. In effect, the negative pulser output issubtracted from the positive amplifier output tocause a null point that can be measured withexcellent sensitivity. The pulser output must bevaried between 0 to 10 V, which usually requires anexternal control source for the pulser. The amplifiergain and the pulser attenuator must be adjusted tomeasure 0 V at the null point when the pulseroutput is 10 V. The variation in the null point as thepulser is reduced gradually from 10 V to 0 V is ameasure of the nonlinearity. Since the subtractionnetwork also acts as a voltage divider, this variationmust be less than

(10 V full scale) × (±0.05% maximum nonlinearity)×(1/2 for divider network)=±2.5 mV for the maximum null-point variation.

OUTPUT LOADING Use the test setup of Fig. 21.Adjust the amplifier output to 10 V and observe thenull point when the front panel output is terminatedin 100 S. The change should be <2.5 mV.

NOISE Measure the noise at the amplifier unipolaroutput with maximum amplifier gain and 3-:sshaping time. Using a true-rms voltmeter, the noiseshould be <5 :V × 750 (gain), or 3.75 mV.

For an average responding voltmeter, the noisereading would have to be multiplied by 1.13 tocalculate the rms noise. The input must beterminated in 100S during the noisemeasurements.

5.3. SUGGESTIONS FORTROUBLESHOOTING

In situations where the 575A is suspected of amalfunction, it is essential to verify suchmalfunction in terms of simple pulse generatorimpulses at the input. The unit must bedisconnected from its position in any system, androutine diagnostic analysis performed with a testpulse generator and oscilloscope. It is imperativethat the testing not be performed with a source anddetector until the amplifier performs satisfactorilywith the test pulse generator.

The testing instructions in Section 5.2 shouldprovide assistance in locating the region of troubleand repairing the malfunction. The two side plates

can be completely removed from the module toenable oscilloscope and voltmeter observations.

5.4. FACTORY REPAIRThis instrument can be returned to the ORTECfactory for service and repair at a nominal cost. Ourstandard procedure for repair ensures the samequality control and checkout as for a newinstrument. Always contact Customer Services atORTEC, (865) 483-2231, before sending in aninstrument for repair to obtain shipping instructions.A Return Authorization Number is required and willbe assigned to the unit. This number should bemarked on the address label and on the package toensure prompt attention when the unit reaches thefactory.

5.5. TABULATED TEST POINT VOLTAGESThe voltages given in Table 5.1 are intended toindicate typical dc levels that can be measured onthe PWB. In some cases the circuit will performsatisfactorily even though, due to componenttolerances, there may be some voltagemeasurements which differ slightly from the listedvalues. The tabulated values should not beinterpreted as absolute voltages but rather shouldbe used as an aid during troubleshooting.

Table 5.1. Typical dc Voltages

Note: All voltages measured with no input signal,with the input terminated in 100 S, and allcontrols set fully clockwise at maximum.

Location Voltage

T1 ±50 mVT2 ±60 mVT3 ±0.7 VT4 ±1.0 VT5 ±60 mVT6 0 to ! 0.8 VT7 ±6 mV

17

Pin Function Pin Function1 +3 V 23 Reserved2 !3 V 24 Reserved3 Spare bus 25 Reserved4 Reserved bus 26 Spare5 Coaxial 27 Spare6 Coaxial *28 +24 V7 Coaxial *29 !24 V8 200 V dc 30 Spare bus9 Spare 31 Spare

*10 +6 V 32 Spare*11 !6 V *33 117 V ac (hot)12 Reserved bus *34 Power return ground13 Spare 35 Reset (Scaler)14 Spare 36 Gate15 Reserved 37 Reset (Auxiliary)*16 +12 V 38 Coaxial*17 !12 V 39 Coaxial18 Spare bus 40 Coaxial19 Reserved bus *41 117 V ac (neutral)20 Spare *42 High-quality ground21 Spare G Ground guide pin22 Reserved

Pins marked (*) are installed and wired inORTEC’s 4001A and 4001C Modular SystemBins.

Bin/Module Connector Pin Assignments For Standard Nuclear Instrument Modules

per DOE/ER-0457T.