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

Gas proportional scintillation counters are room-temperature, 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/√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 _e are calculated, and results are presented for the Fano factor, the w-value and the intrinsic energy resolution as a function of E_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     

The electroluminescence of Xe-Ne gas mixtures: a Monte Carlosimulation study

We have performed a Monte Carlo simulation of the drift of electrons through a mixture of gaseous xenon with the lighter noble gas neon at a total pressure of 1 atm. The electroluminescence characteristics and other transport parameters are investigated as a function of the reduced electric field and composition of the mixture. For Xe-Ne mixtures with 5, 10, 20, 40, 70, 90, and 100% of Xe, we present results for electroluminescence yield and excitation efficiency, average electron energy, electron drift velocity, reduced mobility, reduced diffusion coefficients, and characteristic energies over a range of reduced electric fields which exclude electron multiplication. For the 5% Xe mixture, we also assess the influence of electron multiplication on the electroluminescence yield. The present study of Xe-Ne mixtures was motivated by an interest in using them as a filling for gas proportional scintillation counters in low-energy X-ray applications. In this energy range, the X rays will penetrate further into the detector due to the presence of Ne, and this will lead to an improvement in the collection of primary electrons originating near the detector window and may represent an advantage over the use of pure Xe