Electric field dependence of luminescence due to alpha particles in gaseous xenon and the energy expended per photon

The luminescence yield of gaseous xenon by alpha particles is measured as a function of electric field strength under the pressures of 1.0 and 2.0 atm. The luminescence yield rapidly decreases as increase of the electric field and reaches a constant yield at higher electric field strength. The constant luminescence yield suggests an average energy expended per photon (W/sub s/) is determined from its value. In this study, the W/sub s/ is obtained to be 59.4/spl plusmn/2.4 eV and the ratio of average luminescence yield to average ionization one is calculated to be 0.37/spl plusmn/0.02, which agrees well with Platzman's prediction.