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Ludlum Measurements 15, Manual

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Ludlum Measurements 15 Manual Download Page 5

Ludlum Measurements, Inc. 

 

June 2020 

Table of Contents 

Introduction  

  1 

Getting Started  

  2 

Unpacking and Repacking 

2-1 

Battery Installation 

2-2 

Connecting a Detector to the Instrument 

2-2 

Battery Test 

2-2 

Instrument Test 

2-3 

Operational Check 

2-4 

Specifications  

  3 

Model 42-14H Neutron Detector 

3-2 

Model 44-7 Alpha-Beta-Gamma Detector 

3-2 

Identification of Controls and Functions  

  4 

Safety Considerations 

  5 

Environmental Conditions for Normal Use 

5-1 

Warning Markings and Symbols 

5-1 

Cleaning and Maintenance Precautions 

5-2 

Calibration and Maintenance  

  6 

Calibration 

6-1 

    Calibration of Discriminator  

6-1 

    Calibration of Ratemeter 

6-1 

    Calibration of High Voltage Readout 

6-2 

    Calibration of High Voltage 

6-2 

    Calibration of High Voltage for Neutrons 

6-2 

    Efficiency Calibration 

6-3 

Maintenance 

6-3 

    Recalibration 

6-3 

    Batteries 

6-4 

Troubleshooting 

  7 

Summary of Contents for 15

Page 1: ...LUDLUM MODEL 15 NEUTRON COUNTER WITH DETECTOR MODELS 44 7 42 14H June 2020 Serial Number 336330 and Succeeding Serial Numbers ...

Page 2: ... MODELS 44 7 42 14H June 2020 Serial Number 336330 and Succeeding Serial Numbers This Manual also applies to Serial Numbers of Model 15 Instruments where the accompanying BF 3 detector has been replaced by He 3 He 3 detectors are labeled with an H ...

Page 3: ... any implied warranty of merchantability or fitness which extend beyond the description of the face there of If the product does not perform as warranted herein purchaser s sole remedy shall be repair or replacement at the option of Ludlum Measurements In no event will Ludlum Measurements be liable for damages lost revenue lost wages or any other incidental or consequential damages arising from th...

Page 4: ......

Page 5: ...ma Detector 3 2 Identification of Controls and Functions 4 Safety Considerations 5 Environmental Conditions for Normal Use 5 1 Warning Markings and Symbols 5 1 Cleaning and Maintenance Precautions 5 2 Calibration and Maintenance 6 Calibration 6 1 Calibration of Discriminator 6 1 Calibration of Ratemeter 6 1 Calibration of High Voltage Readout 6 2 Calibration of High Voltage 6 2 Calibration of High...

Page 6: ...l Analog Converter 8 2 Scale Ranging 8 2 Meter Drive 8 2 Meter Compensation 8 2 Fast Slow Time Constant 8 2 Low Voltage Supply 8 3 Low Voltage Reference 8 3 High Voltage Supply 8 3 Recycling 9 Parts List 10 Model 15 Neutron Counter with Detectors 10 1 Main Board Drawing 464 x 655 10 1 Calibration Board Drawing 363 585 10 3 Wiring Diagram Drawing 363 587 10 4 Drawings and Diagrams 11 ...

Page 7: ...eaker with audio ON OFF capability fast slow meter response meter reset button and a six position switch for selecting battery check or range multiples of 1 10 100 and 1000 Each range multiplier has its own calibration potentiometer Other controls include two position toggle switch for selection of alpha beta gamma B G or neutron detection N high voltage check HV and meter reset RES buttons and fr...

Page 8: ...ortant If multiple shipments are received ensure that the detectors and instruments are not interchanged Each instrument is calibrated to specific detectors and therefore not interchangeable To return an instrument for repair or calibration provide sufficient packing material to prevent damage during shipment Every returned instrument must be accompanied by an Instrument Return Form which can be d...

Page 9: ...t Caution The detector operating voltage HV is supplied to the detector via the detector input connector A mild electric shock may occur if you make contact with the center pin of the input connector Switch the Model 15 range selector switch to the OFF position before connecting or disconnecting the cable or detector Connect one end of a detector cable to the desired detector by firmly pushing the...

Page 10: ...he fast and slow response time F S positions to observe variations in the display The S position should respond approximately five times slower than the F position Note The slow response position is normally used when the instrument is displaying low numbers which require a more stable meter movement The fast response position is used at high rate levels Check the meter reset function by depressin...

Page 11: ...Inc Page 2 4 June 2020 Operational Check To assure proper operation of the instrument between calibrations and periods of nonuse an instrument operational check including battery test and instrument test as described above should be performed prior to use ...

Page 12: ...ly 0 500 000 cpm depending on the meter face utilized Linearity reading within 10 of true value with detector connected Audio built in unimorph speaker with ON OFF switch greater than 60 dB at 0 61 m 2 feet Connector series C other available Power two D cell batteries housed in a sealed externally accessible compartment Battery Life typically 600 hours with alkaline batteries battery condition may...

Page 13: ...ar throughout energy spectrum 0 025 12 MeV Neutron Sensitivity typically 55 cpm mrem hr 241 AmBe fast neutrons Detection Range thermal to approximately 12 MeV Gamma Rejection typically 10 cpm or less through 10 R hr 100 mSv h 137 Cs Alpha Beta Gamma Detector thin end window GM detector Window 2 0 0 3 mg cm2 mica Window Area active is 6 4 cm2 1 in2 open is 5 2 cm2 0 8 in2 Efficiency 4pi geometry ty...

Page 14: ...to 500 000 cpm Multiply the scale reading by the multiplier to determine the actual scale reading Battery Compartment sealed compartment to house two D cell batteries AUD ON OFF Toggle Switch in the ON position operates the unimorph speaker located on the left side of the instrument The frequency of the clicks is relative to the rate of the incoming pulses The higher the rate the higher the audio ...

Page 15: ...oltage on the meter face corresponding to the selected detector B G N The output resistance of the high voltage supply is 1 5 megohms with a typical scintillation voltage divider of 100 megohms The actual detector voltage will be 98 5 of the indicated voltage The following controls are located under the front panel calibration cover Discriminator Adjustment DIS allows the input pulse threshold to ...

Page 16: ...aximum relative humidity of less than 95 non condensing Pollution Degree 3 as defined by IEC 664 Occurs when conductive pollution or dry nonconductive pollution becomes conductive due to condensation This is typical of industrial or construction sites Warning Markings and Symbols Caution The operator or responsible body is cautioned that the protection provided by the equipment may be impaired if ...

Page 17: ...ntact with internal hazardous live parts that are accessible using a tool 1 Turn the instrument power OFF and remove the batteries 2 Allow the instrument to sit for one minute before accessing internal components The crossed out wheelie bin symbol notifies the consumer that the product is not to be mixed with unsorted municipal waste when discarding each material must be separated The symbol is pl...

Page 18: ...e pulser s pulse height to 10 0 5 mV for use without a GM detector If a GM detector is used set the pulse height to 30 0 5 mV Set the pulser s pulse rate to 400 10 counts per minute Adjust the DIS control until the meter reading increases from 0 to a stable reading near 400 counts per minute Check the adjustment by lowering the Model 500 pulser s pulse height to 9 mV for 10 mV setting or 29 mV for...

Page 19: ...r Set the B G N switch to N Press the HV Test switch and record the HV reading on both the Model 500 and the Model 15 Adjust the HVN potentiometer for 1500 V on pulser readout Press the HV button and adjust the internal Model 15 HV control until the meter reads 1500 V Reduce the HVN control for 1000 V on pulser HV readout HV test should indicate 1000 10 Increase the HVN control to 2000 V on Pulser...

Page 20: ...xposed to a known gamma field Determine counts minute per mR hr Maintenance Instrument maintenance consists of keeping the instrument clean and periodically checking the batteries and the calibration The Model 15 instrument may be cleaned with a damp cloth using only water as the wetting agent Do not immerse instrument in any liquid Observe the following precautions when cleaning 1 Turn the instru...

Page 21: ...ed any time the instrument is placed into storage Battery leakage may cause corrosion on the battery contacts which must be scraped off and or washed using a paste solution made from baking soda and water Use a spanner wrench to unscrew the battery contact insulators exposing the internal contacts and battery springs Removal of the handle will facilitate access to these contacts Note Never store t...

Page 22: ...ed are 1 detector cables 2 sticky meters and 3 battery contacts Note that the first troubleshooting tip is for determining whether the problem is with the electronics or with the detector A Ludlum Model 500 Pulser is invaluable at this point because of its ability to simultaneously check high voltage input sensitivity or threshold and the electronics for proper counting We hope these tips will pro...

Page 23: ...check the HV ensure that one with high impedance is used as a standard multimeter could be damaged in this process 2 Check for noise in the detector cable by disconnecting the detector placing the instrument on the lowest range setting and wiggling the cable while observing the meter face for significant changes in readings 3 Check for sticky meter movement Does the reading change when you tap the...

Page 24: ...ween the speaker and the input preamplifier may cause noise 1 Substitute a known good detector and or cable 2 Has the correct operating voltage been set Refer to the calibration certificate or detector instruction manual for correct operating voltage If the instrument uses multiple detectors confirm that the high voltage is matched to the current detector being used 1 Ensure that the AUD ON OFF sw...

Page 25: ...proximately 1 4 V providing just enough bias current to conduct all of the current from the current mirror Positive pulses from U10 are coupled to the discriminator Discriminator Comparator U2 provides discrimination The discriminator is set by the DIS discriminator control located on the front panel coupled to pin 3 of U2 These pulses are coupled to pin 5 of U3 for meter drive and pin 12 of U3 fo...

Page 26: ...eir related capacitors This arrangement allows the same current to be delivered to C105 by one count on the X1 range as 1000 counts on X1K range Meter Drive The meter is driven by the emitter to Q6 coupled as a voltage follower in conjunction with pin 1 of U6 For ratemeter drive the meter is coupled to C105 at P1 15 For high voltage the meter is coupled to R132 at P1 11 For battery test the voltag...

Page 27: ...igh Voltage Supply High voltage is developed by blocking oscillator Q145 T165 and rectified by voltage multiplier CR166 167 169 and 175 Output voltage increases as current through Q44 increases with maximum output voltage with Q44 saturated High voltage is coupled back through R47 R90 to opamp pin 6 of U6 R147 completes the high voltage circuit to ground High voltage output is set by front panel c...

Page 28: ...imply desires to inform its consumers of the range of recyclable materials present in its products so that the user will have flexibility in following all local and federal laws The following types of recyclable materials are present in Ludlum Measurements Inc electronics products and should be recycled separately The list is not all inclusive nor does it suggest that all materials are present in ...

Page 29: ...0pF 3kV 04 5532 C102 100µF 10V 04 5576 C103 10µF 20V 04 5592 C104 100µF 10V 04 5576 C105 22µF 35V 04 5594 C106 0 001µF 100V 04 5519 C109 0 01µF 100V 04 5523 C111 0 01F 100V 04 5523 C112 470pF 100V 04 5555 C113 0 01µF 100V 04 5523 C115 0 01µF 100V 04 5523 C117 47pF 100V 04 5533 C119 0 001µF 100V 04 5519 C121 330pF 100V 04 5531 C122 0 0047F 3kV 04 5547 C126 10µF 20V 04 5592 C134 100µF 10V 04 5576 C1...

Page 30: ...MXT3904TRLF 05 5888 U5 ICM7555 06 6136 U6 TLC27M7IP 06 6248 U7 MAX631 06 6249 U8 CMXT3904TRLF 05 5890 U9 U10 CMXT3904TRLF 05 5888 U101 LM385Z 1 2 05 5808 CR94 1N4148 07 6272 CR166 CR167 GI250 2 07 6266 CR169 GI250 2 07 6266 CR175 GI250 2 07 6266 RT1 RT2 150 OHM 07 6332 R132 1M 09 6814 R3 634 OHM 12 7808 R18 1k 10 7009 R27 1 MEG 10 7028 R28 4 7 MEG 10 7030 R36 1 MEG 10 7028 R46 10k 10 7016 R47 R48 ...

Page 31: ... 7029 R87 10k 10 7016 R89 R90 100k 10 7023 R91 4 7k 10 7014 R128 100k 10 7023 R137 10k 10 7016 R138 1 MEG 10 7028 R147 432k 12 7689 R150 2 37k 12 7648 R159 10k 10 7016 R172 47k 10 7020 R177 200 OHM 10 7006 P1 CONN 1 640456 6 MTA100X16 13 8134 P2 CONN 640456 2 MTA100X2 13 8073 W2 W29 CLOVERLEAF RECEPTACLE 18 8771 L13 470uH 21 9600 T165 T165 40 0902 BOARD Completely Assembled Calibration Board 5363 ...

Page 32: ...3 CONN 640456 6 MTA100 13 8095 P4 CONN 640456 4 MTA100 13 8088 J1 CONN 1 640442 6 13 8187 J2 CONN 640442 2 MTA100 13 8178 J3 CONN 640442 6 MTA100 13 8171 J4 CONN 640442 4 MTA100 13 8170 J5 RECPT UG706 U SCREW IN C 13 7751 DS1 UNIMORPH TEC 3526 PU 21 9251 B1 B2 D CELL BATTERY 21 9313 S1 PA 600 210 08 6501 S2 923 SWTCHCRFT 08 6518 S3 30 1 PB 08 6517 S4 S6 7101 SYZ QE 08 6511 M1 PORT BEZEL W MVMNT AS...

Page 33: ...W O BATT LID 4363 349 PORT HANDLE ROLLED W SCREWS 7363 139 PORT HANDLE FOR CLIP W SCREWS 7363 203 REPLACEMENT CABLE STD 39 inch 40 1004 CLIP 44 3 TYPE W SCREWS 7002 026 01 CLIP 44 7 TYPE W SCREWS 7010 007 01 CLIP 44 6 TYPE W SCREWS 7010 008 01 MODEL 44 7 END WINDOW GM PROBE 47 1536 MODEL 15 MODERATOR W 42 14H NEUTRON PROBE 47 1575 MISCELLANEOUS DETECTORS ...

Page 34: ...ture Compensation Drawing 464 655 MAIN CIRCUIT BOARD LAYOUT Drawing 464 658 2 sheets CALIBRATION BOARD Drawing 363 585 CALIBRATION BOARD LAYOUT Drawing 363 586 2 sheets WIRING DIAGRAM Drawing 363 587 MODEL 42 14H DETECTOR ASSEMBLY Drawing 204 16 MODEL 44 7 DETECTOR ASSEMBLY Drawing 2 157 MODEL 44 7 ENERGY RESPONSE CURVE Section 11 ...

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