Absorption of electrons in xenon for energies up to 200 keV: a Monte Carlo simulation study

Abstract

Gas proportional scintillation counters are roomtemperature, general-purpose x-ray detectors, which are used in many applications due to their good energy resolution, which can be better than standard proportional counters by a factor of -2. However, for energies higher than -20 keV, the experimentally measured energy resolution is found to deviate from the usual 1 d E law. Under these circumstances, it is of great interest to understand the mechanisms involved in the detection of higher energy x-rays. Since the photoelectrons will then carry most of the absorbed energy, we study in this work the response of xenon detectors, to electrons with energies up to -200 keV, using a Monte Carlo simulation technique. Distributions of the number of primary (subionization) electrons produced per parent electrons with energy E, are calculated, and results are presented for the Fano factor, the w-value and the intrinsic energy resolution as a function of E, in the range 20-200 keV. The influence of an applied reduced electric field on the results is assessed, showing that for 200 keV electrons an increase in the field from 0.1 to 0.8 Td causes an increase as high as 35% in the intrinsic energy resolution.

Monte Carlo model for electron degradation in xenon gas

“…The electron collision process in xenon was studied earlier by Date et al [17] using a Monte Carlo method. Rachinhas et al [18] studied the absorption of electrons with energies ≤ 200 keV in xenon using a Monte Carlo simulation technique. They calculated mean energy per ion pair (w-value) and Fano factor in the energy range 20-200 keV and studied the influence of electric field on the results.…”

A simulation study of the effect of drift electric fields on the response of radiation detectors using the PENELOPE code

“…We first noticed this subtle field effect in a detailed Monte Carlo study of the w-value, Fano factor F, and intrinsic energy resolution in Xe for the absorption of electron beams with energies E e up to 200 keV [6], where we encountered an unexpected dependence of F and w on the applied drift field. For the absorption in Xe of X-rays with energies E ph in the range 60-200 keV, we later analysed in Ref.…”