Account of scintillation efficiency for low-velocity heavy ions

The track-effect theory of scintillation efficiency is generalized for applicability at low velocities and applied to room-temperature pulse-height data (L vs E) for keV-energy heavy ions (6≤Z≤80) in CsI(Tl). By subtraction of the elastic-collision-loss contribution to the total energy, data are reduced to the form dLdη vs velocity, where dLdη is the differential light emission per unit of electronic energy deposit. It is found that agreement between theory and experiment is achieved over the entire range of the data with no specific role attributed to elastic scattering other than the consumption of a portion of the energy of the incident ion. The role of electron promotion in determining the pulse-height characteristics is examined. Those features of the model developed specifically for low-velocity application are presented. Results of the treatment and implications regarding the degree of applicability of the track-effect model are discussed.