Luminescence efficiency of Al2O3:C,Mg radiophotoluminescence in charged particle beams

In hadron therapy, it is important to evaluate how sensitive a detector is upon radiation with varying ionization densities, i.e. linear energy transfer (LET), as the LET changes when penetrating through material. For solid-state detectors, it is therefore essential to characterize the luminescence efficiency (eta(HT,gamma)) of the detector as a function of LET. In this work, we investigate the radiophotuminescence (RPL) response from Al2O3:C,Mg 2D films and crystals exposed to various high LET beams (H-1, He-4, C-12, Si-28 and Fe-56). The measured eta(HT,gamma) curve from RPL films and crystals as function of the particle LET is compared with the eta(HT,gamma) if curve from Al2O3:C OSL samples. Furthermore, a 2D RPL image, from Al2O3:C,Mg films irradiated with a 61.3 MeV 40 mm diameter broad proton beam, depicts a 2D depth dose distribution of the Bragg peak and demonstrates similar LET dependence as from the luminescence efficiency curve. The eta(HT,gamma) curves are consistent with Birks' law, where we observe expected quenching for increasing LET.