A simple approach to X-ray spectrometry with driftless gas proportional scintillation counters

Driftless gas proportional scintillation counters (GPSCs) are used not only for soft X-ray spectrometry but also for X-rays with energies in the 0.1 to 25-keV region. At the higher energies, however, pulse amplitudes will depend on where the absorption occurred in the detector. Pulse-shape analysis with either analog or digital pulse techniques is required to restore proportionality between the measured pulse and the energy of the X-ray. In this paper, we describe a simpler approach to driftless GPSC spectrometry at higher energies. The method eliminates the requirement for additional analog electronics or digital signal processing with only a modest amount of energy-dependent degradation in overall performance. The approach relies on short amplifier time constants and allows tradeoffs in the design of X-ray spectrometers whose performance requirements do not justify the complexity of a fully compensated system. We report the results of a comprehensive study of the performance characteristics of a driftless GPSC using short time constants with no additional compensation and compare its performance with that of a fully compensated digital system as a function of X-ray energy.