On the scintillation response of NaI(Tl)-crystals

Several articles hare been reviewed on the scintillation response of NaI(Tl). Those publications which report results obtained with radioactive sources either dispersed throughout the NaI(Tl)-lattice or located inside the wells of NaI(Tl)-crystals match within a +/-0.9% standard deviation of a linear scintillation response between 3 MeV and 3 keV, Several authors wire placed their sources outside the crystals measured nonlinear responses of NaI(Tl) with up to +/-7% of standard deviations between 700 and 4.5 keV. The presented analysis suggests that the observed nonlinearity is not an intrinsic effect of NaI(Tl) but could he caused, at least partly, by effects occurring at the radiation entrance surfaces of the crystals.