Comparative study of gas amplification and energy resolution in some argon-based mixtures

Abstract

A mean gas amplification factor M in mixtures of argon with propane and DME at various pressures ⩽50 kPa is studied. The deviations from the linear dependence of gas gain on high voltage in a semi-log plot are compared with those observed earlier in argon–isobutane mixtures. In all three kinds of mixtures, the magnitude M 0 of the gas gain where deviations start depends on the partial pressure of the admixture. Energy resolution at 5.9 keV has been measured in pure gases and in argon-based mixtures as a function of the gas gain. The best resolution has been obtained at low gas gains, ∼100–200. At these gains better resolution is obtained for mixtures with lower partial pressure of the admixture. At high gas gains energy resolution depends strongly on the admixture partial pressure, and above M 0 it degrades much faster due to avalanche chain formation.