Specifications

Table of Contents
2
USING PHOTOMULTIPLIER TUBES
PMT Selection for Photon Counting 63
Geometry 63
Spectral Response 63
Gain and Risetime 63
Dark Counts 64
PMT Base Design 64
Dynode Biasing 64
Snubbing 66
PMT Base Conclusions 67
Cathode Shielding 67
Preamplifiers 67
Gain Requirement 67
Plateauing a PMT 67
The 'Correct' Way 68
The 'Fast and Pretty Good' Way 68
TYPICAL EXPERIMENT
Energy Levels of Ruby 69
Apparatus 69
Operation 69
Instrument Configuration 70
Computer Data Acquisition 70
CIRCUIT DESCRIPTION
Microprocessor Control 73
Microprocessor System 73
RS-232 Interface 73
GPIB Interface 73
Input Ports 73
Slow Counters 73
Output Ports 73
Front Panel 73
D/A Converter 74
Fast Counters 74
Signal Inputs 74
Discriminators 74
A and B Counters 74
T Counter 75
Start / Stop and Dwell 75
Gate Generators 76
Digital Delay 76
Analog Delay 76
Delay Reset 77
Gates 77
Power Supply 77
PARTS LISTS
Main Assembly 79
Power Supply 93
Miscellaneous 95
SCHEMATIC DIAGRAMS
Signal Amplifiers SR400-1
Discriminators SR400-2
Fast Counters A and B Prescallers SR400-3
Fast Counters T Prescaller SR400-4
Slow Counters (A, B, T) SR400-5
Dwell Timer: Start/Stop SR400-6
Fast Gate Delay Ramps SR400-7
Slow Gate Delay Counters SR400-8
Fast Gate Ramps SR400-9
Width Oscillators SR400-10
Slow Gate Width Counters SR400-11
Microprocessor System SR400-12
Counters and Timers:
Digital Interface 1 SR400-13
Output Ports:
Digital Interface 2 SR400-14
Digital to Analog Converter SR400-15
Power Supply