Spectroscopic analysis of proton-induced fluorescence from yttrium and gadolinium oxysulfide phosphors

The effect of proton-induced damage on the relative scintillation efficiency of various inorganic phosphors was determined. Proton-induced degradation of phosphors such as Y/sub 2/O/sub 2/S:Eu, Gd/sub 2/O/sub 2/S:Pr, and Gd/sub 2/O/sub 2/S:Tb was studied. Materials were selected for high efficiency, fast prompt fluorescence response, and minimal delayed fluorescence. Phosphors were exposed to a 3-MeV proton beam at ambient temperatures to control heating damage. Real-time, in situ measurements of the fluorescence spectra permitted observation of the spectral characteristics for the deterioration of scintillation yield due to particle-induced damage. The light spectra emitted were nearly identical to those excited by electrons, indicating a common excitation process. Rare earth oxysulfides give intense emissions but the corresponding light intensity drops rapidly with dose. Light intensity decreases with dose, following the Birks and Black model where damage sites compete for excitons with light-producting sites. Decay of broadband and spectral peak intensity follows similar patterns.<
>