Performance characteristics of a gas proportional scintillation counter coupled to a microstrip gas chamber photosensor

A P10-filled microstrip gas chamber (MSGC) is used to replace the conventional photomultiplier tube (PMT) as the photosensor for a Gas Proportional Scintillation Counter (GPSC). The Vacuum Ultra-Violet (VUV) scintillation light produced in the xenon-filled GPSC is transmitted through a 1 mm thick high-purity quartz window to the MSGC where it is converted to photoelectrons by a CsI photocathode deposited directly onto the surface of a microstrip plate (MSP). These photoelectrons are afterwards multiplied near the microstrip plate anodes with a charge gain of about 103. The energy resolution achieved for 5.9 keV X-rays is 11.5% which, while not yet as good as the 8% figure for standard GPSC (instrumented with a PMT), is already better than the energy resolution obtained for standard proportional counters. Experimental results are presented and discussed. With this design a compact GPSC is obtained which has the further advantage of being much less sensitive to magnetic fields than PMT-based GPSCs.