Data aquisition and -evaluation electronics for the Rosat PSPCs

Abstract

The German X-ray satellite Rosat will carry two redundant position sensitive proportional counters (PSPC) and a high resolution imager. For the PSPCs the corresponding front-end and evaluation electronics were designed and built at the MPI. For each accepted X-ray event in the energy range from 0.1 to 2.0 keV the energy and the arrival time as well as the location are determined. In order to reduce the telemetry data rate, the event location is calculated on board, using a microcomputer. A newly designed electronical background suppression system for charged particles was incorporated. By this system, a suppression efficiency of 97.5% was measured. Together with a five sided anticoincidence, 99% was achieved. Each of the PSPCs, of which only one at a time is active, contains its own charge sensitive amplifiers and pulse shapers. The analog signals of the PSPCs 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/s can be evaluated.