Determination of electron lifetime in compressed Xe gas for gamma-spectroscopy

High-pressure xenon gas (HPXe) has been used as the active medium in radiation detection applications: gamma spectroscopy, neutron spectroscopy, neutrino detection, etc. In recent years, gamma-spectrometers based on HPXe, in particular, have achieved high energy resolution (<1.7% at 662 keV) and great detection efficiency. In order for Xe to have good electronic qualities, it needs to be of high purity. This work reports on the determination of the charge carrier lifetime in Xe, which reflects its purity and characterizes the quality of the gas for gamma-spectroscopy. Our previously developed analytical model for charge transport in an ionization chamber filled with Xe is used to determine the electron lifetime in Xe in the parallel-electrode configuration. The model is used to fit the measurement results obtained by using a dedicated ionization chamber. For undoped Xe gas of approximately 6N purity, the dependence of the ionization pulse rise time vs. gas pressure was measured. By using the data and the analysis, the lifetime at each pressure was estimated.