Charge collection and energy resolution studies in compressed xenon gas near its critical point

Abstract

We have built a 4.5 l high purity Xe gas ionization chamber and operated it at pressures of up to 62 atm (1.4 g/cm 3) at room temperature. This thermodynamic regime in pure xenon has not previously been studied. Ionization from a 207Bi internal conversion electron source was drifted over distances of 2.7 and 5.0 cm in two separate gridded ionization chambers within the gas volume. We observed that there was less than 1% difference in the charge collected from these two detectors at the same electric field strength. Energy resolution measurements were performed over the range of xenon densities from 0.49 to 1.40 g/cm 3 at several electric field strengths. An electronic noise subtracted resolution of 16 keV FWHM was measured for the 976 keV 207Bi internal conversion line at an electric field strength of 1.3 kV/cm in compressed xenon gas near its critical density.