Xenon GPSC high-pressure operation with large-area avalanche photodiode readout

The performance of a xenon high-pressure gas proportional scintillation counter (GPSC) instrumented with a large area avalanche photodiode (LAAPD) as the VUV-photosensor has been investigated for filling pressures from 1 up to 10 bar, for 22- and 60-keV photons. The LAAPD photosensor is placed directly within the xenon envelope, as a substitute for the photomultiplier tube, avoiding the constraints of the use of a quartz scintillation window for GPSC-photosensor coupling, which absorbs a significant amount of scintillation and is a drawback for applications where large detection areas and high filling pressures are needed. The lowest energy resolutions are achieved for pressures around 5 bar (4.5% and 3.0% full width at half-maximum (FWHM), for 22- and 60-keV photons, respectively). Increasing the pressure to the 8 bar range, competitive energy resolutions of 5.0% and 3.6% are still achieved for 22- and 60-keV photons, respectively. This detector could be a compelling alternative in applications where compactness, large detection area, insensitivity to strong magnetic fields, room temperature operation, large signal-to-noise ratio and good energy resolution are important requirements.