X-ray-induced radiation damage in CsI, Gadox, Y2O2S and Y2O3 thin films

The stability of CsI, CsI(Tl), Gd2O2S(Tb), Gd2O2S(Eu), Y2O2S(Eu) and Y2O3(Eu) thin films under bombardment by 9–18 keV X-rays is described. Both external photocurrent and scintillation light yield were measured as functions of accumulated dose at radiation fluxes of 106–107 photons s−1 mm−2 on Beamline 2.2 of the Daresbury Synchrotron Radiation Source (SRS). All of the samples studied showed changes of several percent (both reductions and increases) in photocurrent and scintillation light yield of several percent for accumulated doses of up to 5×1011 photons mm−2. No significant dependence of the film response on the angle of X-ray incidence was observed for angles up to 45° from the normal. It was found that the accumulated dose is not the only parameter determining the degradation of photoconverter performance; the flux rate has also to be taken into account. Scanning Electron Microscope studies of the irradiated samples did not reveal any significant surface modification.