Three Pointed Proportional Counters(PPC)
The PPC is a multi-cell multi-layer proportional counter array with active anticoincidence on three sides. The total geometric area is about 400 cm2 and the filling gas is 90% Argon + 10% Methane. A 25 micron aluminized mylar acts as the entrance window. The field of view is restricted to 2o X 2o by a passive collimator. The detector has a command controlled high voltage unit. The processing electronics for the PPC has an onboard memory of 512 kbytes and the spectra (64 channels spanning 2 to 30 keV) and light-curves are stored onboard with the command selectable integration times. Automatic South Atlantic Anomaly (SAA) recognition, selectable thresholds, storage of calibration data etc. are the additional features available in the onboard processor.