Data acquisition and evaluation electronics for the ROSAT Position Sensitive Proportional Counters (PSPC's)

Front-end and evaluation electronics for the ROSAT position sensitive proportional counters (PSPC) were designed and built. For each accepted X-ray event in the energy range from 0.1 to 2.0 keV, the energy and the arrival time, and the location are determined. In order to reduce the telemetry data rate, the event location is calculated on board. An electronic background suppression system for charged particles was incorporated. With this system, a suppression efficiency of 97.5% is measured. With a five-sided anticoincidence, 99% is achieved. Each of the PSPC's, of which only one at a time is active, contains its own charge sensitive amplifiers and pulse shapers. The analog signals of the PSPC's are mixed and routed to the commonly used analog evaluation electronics and the microcomputer. In order to reduce the number of peak detectors and analog to digital converters, the signals are multiplexed. Up to 1000 events/sec can be evaluated.