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Summary of Contents for ORTEC A-576 A-PAD

Page 1: ...Model A 576 A PAD Preamplifier Amplifier Discriminator with Bias Supply Operating and Service Manual Printed in U S A ORTEC Part No 761930 0202 Manual Revision D ...

Page 2: ... that a Return Authorization Number can be assigned to the unit Also ORTEC must be informed either in writing by telephone 865 482 4411 or by facsimile transmission 865 483 2133 of the nature of the fault of the instrument being returned and of the model serial and revision Rev on rear panel numbers Failure to do so may cause unnecessary delays in getting the unit repaired The ORTEC standard proce...

Page 3: ...NECTION TO POWER 4 3 4 OUTPUT CONNECTIONS 4 3 5 ENERGY OUTPUT FULL SCALE ADJUSTMENT 4 4 OPERATION 5 4 1 GENERAL 5 4 2 CONNECTING A DETECTOR 5 5 THEORY OF OPERATION 6 LIST OF FIGURES Fig 1 Block diagram of Alpha Spectrometer 1 Fig 2 Jumper Locations for Setting Polarity on the PWB 3 Fig 3 Side Panel Test Pulser Selection 4 Fig 4 Typical A PAD Output Waveforms with 5 MeV Test Pulser 5 Fig 5 Detailed...

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Page 5: ...MeV by includes a variable detector bias supply a internal jumper selection preamplifier a shaping and stretching amplifier a biased amplifier a test pulser and a discriminator In addition to the calibrated Energy output the Fig 1 The detector bias supply and the amplifier COUNT front panel BNC connector provides a NIM have selectable polarity so that it can be ued with any standard positive logic...

Page 6: ...o give a 4 µs wide positive output pulse INPUT BIAS POLARITY PWB jumpers allow ENERGY RANGES 3 TO 8 MeV 4 to 7 MeV 3 to 5 polarity Negative for ORTEC Surface Barrier or Ion MeV 4 to 6 MeV 5 to 7 MeV 6 to 8 MeV Implanted Ruggedized detectors or positive for conventional detectors Shipped in Negative position CALIBRATED TEST PULSER Equivalent Energy 5 MeV 6 MeV or 7 MeV Shipped at 5 MeV Rate is 100 ...

Page 7: ...are accessible when the side panel is removed from the instrument chassis Five of the jumpers are used to select either positive or negative detector voltage polarity and the corresponding correct amplifier polarity Negative bias is required for ORTEC Ruggedized detectors positive for conventional surface barrier or ion implanted detectors These five internal jumpers need to be changed only when a...

Page 8: ...ut PREAMP IN connector on the A PAD For best Continue with operation of the A 576 results keep the length of this cable as short as possible due to the capacitive loading of the cable to minimize preamplifier noise and maintain the preamplifier stability Type RG 62 U cable is recommended for the detector to preamplifier connection This is 93 6 cable with a capacity of 13 5 pF ft 3 3 CONNECTION TO ...

Page 9: ...e bias voltage with a 6 µs width shown in Fig 4 ON may damage the FET transistor at the input of the preamplifier or destroy the detector 4 System electronic noise can be tested by Then proceed as follows the MCA from the ENERGY output 1 With the bias OFF connect the detector to the 5 The test pulser can then be turned OFF by moving A PAD with a short cable preferably RG 62A U the TEST BIAS OFF sw...

Page 10: ...es at the J3 location in the circuit COUNT output signal The pulse from the second The 100 V power supply output on the PWB can be If the stretcher is enabled the peak amplitude is tested for both polarity and amplitude at test point stretched to improve the measurement accuracy of the TP1 which is identified on the PWB The variable 0 to multichannel analyzer which uses the ENERGY 100 V bias volta...

Page 11: ...etected input energy exceeds the selected bias MeV range The output of the biased amplifier is a level The full scale output of 10 V can be adjusted positive pulse with an amplitude in the range from 0 1 down to 7 75 V using the front panel screwdriver to 10 V which is proportional to the amount by which control E ...

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