Scintillation and ionization yields produced by in high-density gaseous xenon

The average numbers of scintillation photons and liberated electrons produced by 5.49-MeV α - particles were measured in high-density gaseous xenon. The density range is 0.12–1.32 g/cm3 for scintillation measurements at zero electric field, and 0.12–1.03 g/cm3 for the scintillation and ionization measurements under various electric fields. The density dependence of scintillation yield at zero electric field was observed. The W s - value , which is defined as the average energy expended per photon, increases with density and becomes almost constant in the density range above 1.0 g/cm3. Anti-correlations between average numbers of scintillation photons and liberated electrons were found to vary with density. It was also found that the total number of scintillation photons and liberated electrons decreases with increasing density. Several possible reasons for the variation in scintillation and ionization yields with density are discussed.