The AD8 amplifier-discriminator is a compact, low noise, high gain electronics module designed to be used in photomultiplier photon counting systems to generate TTL output pulses. An output pulse of fixed width and amplitude is produced for each photomultiplier output pulse that exceeds the input discriminator threshold level. The threshold level is fixed to -2 mV, which is sufficiently sensitive to enable most photomultipliers with 10 or more dynodes to operate in single photon counting mode.
Two outputs are provided; one with a pulse-pair resolution of 25ns for input count rates up to 150Mcps, and the other with a pulse-pair resolution of 10µs for rates up to 100kcps. The slower output is intended to be used where it is required to eliminate photomultiplier afterpulses.
The AD8 is housed in a metal box and is compatible with the ET Enterprises MCS-CT3 multi-channel scaler/counter-timer. When used together, the AD8 can be powered from theMCS-CT3. These units are also compatible with the ET Enterprises range of ambient temperature and cooled photomultiplier housings, enabling high performance and costeffective photon detection systems to be set up with minimal effort.