The energy resolution of high-pressure xenon-filled proportional counters

The performance characteristics of xenon-filled proportional counters with different anode diameters have been measured for fill gas pressures from 1 to 10 atm. For 25 mu m anodes the resolution in pure xenon, for example, degrades from 7.5% at 1 atm to 9.4% at 10 atm, the corresponding figures for 12.5 mu m anodes being 7.1% and 9.1%, respectively. It is shown that these data are consistent with changes in the field in the avalanche region, which modify the energetics of the avalanche process, affect the partition of energy into ionization and excitation, and ultimately influence the statistics of the charge amplification process.<>