Experimental Study of the $w$-Values and Fano Factors of Gaseous Xenon and Ar-Xe Mixtures for X-Rays

Abstract

An experimental study of the -values and Fano factors for Ar-Xe gaseous mixtures at atmospheric pressures for 5.895 keV X-rays was carried out with two experimental set-ups based on gas proportional scintillation counter techniques. For the 100% Xe, Ar-40% Xe, Ar-20% Xe and Ar-10% Xe mixtures at 800 Torr the measured -values were 21.61 eV, 21.63 eV, 21.64 eV and 21.42 eV, respectively, within an accuracy of 0.21 eV. For the same mixtures the Fano factors were 0.254, 0.258, 0.250 and 0.256, respectively, within an accuracy of about 0.004. For lower Xe concentrations of 5%, 3% and 1% the Fano factors were 0.24, 0.23 and 0.22, respectively. These experimental results are compared with those available in the literature.

An InGrid based Low Energy X-ray Detector for the CAST Experiment

“…Additionally energy resolutions σ E /E of down to 3.85 % at 5.9 keV could be achieved at optimized settings in a gas mixture of Argon and isobutane with 10 % quencher fraction and energy determination by simple pixel (or electron) counting. This value, however, is already close to the lower limit of roughly 3 % given by the Fano factor [17]. The corresponding spectrum is shown in figure 4c, again the number of fired-pixels is taken as measure of the photon energy.…”

Quenched and Non-Quenched Ar-Xe Penning Mixtures as Detection Media for a Gridded-Microstrip Gas Chamber X-Ray Detector

“…Another parameter, the gas multiplication factor, , that characterizes gas avalanche detectors, can be also estimated from a comparison of pulse-height spectral peaks generated by a 5.9 keV X-ray source and a charge calibrator: (2) where is a 2 pF calibrated capacitor, is the amplitude of the test pulse from the pulse generator, is the average energy required to produce an electron-ion pair in the gas, is the electron charge and and are the channel numbers, in the multichannel analyzer, for the test pulse and for the X-ray (with energy ) charge pulse collected at the anode, respectively. Although the -values for pure Xe and Ar and their mixtures can be found in the literature [17] this is not true for the case of P10-Xe mixtures. In these cases, instead of the gas multiplication factor , we used pulse amplitudes to characterize the gas gain of each studied mixture as will be described in Sections IV and V. Pulse amplitudes are proportional to the position of the centroid of the gaussian fitted to spectrum main peak, , i.e.…”

A new technique for gaseous gamma ray detectors: The multigrid high pressure xenon gas proportional scintillation counter

“…2 = intrinsic limit, which is 0.6 % for 662 keV in Xe assuming a Fano factor F=0.25 and w=21.6 eV [10].…”

“…This detector consist of a high pressure Xe filled cylinder at ground potential with 4 circular grids parallel to each other and to a CsI film (about 500 nm thick), vacuum evaporated in the lower and inner surface of the detector. The ionizing radiation is absorbed, mainly by photoelectric and Compton processes, in the 5 to 20 cm long HPXe drift region (at a pressure p in the 5-20 atm range), where the electric field is below the 1 V.cm -1 .Torr -1 threshold for secondary scintillation, and produces n primary electrons (n §30,000 electrons for a 662 keV γ-photon) [10].…”