FUNDAMENTAL MECHANISMS DETERMINING THE PERFORMANCE OF GAS PROPORTIONAL DETECTORS

The average ionic charge created in Ar, Kr and Xe as a result of X-ray photoabsorption has been determined using time-of-flight mass spectro scopy in conjunction with synchrotron radiation (XTOFS). Measurements were carried out at the Ni K edge, 1.5 angstrom. Calculations predicti ng the degree of electron multiplication expected from inelastic colli sions in the gas at atmospheric pressures have been performed. Theory is found to be in agreement with present experimental findings. The es timated total electron yield in the gas is a guide in the determinatio n of the efficiency of a gas proportional counter. Xenon gas is found to be the preferred candidate.