Proton-Induced Activation of New Scintillator Materials: SrI, GAGG, CLLB, CLLBC, TLYC, CLYC-7

In recent years, a number of new scintillator materials with improved energy resolution for gamma-ray detectors have become commercially available for use in terrestrial-based homeland security applications, and some are being incorporated into instrumentation for space. Unlike terrestrial applications, the harsh environment of space-in particular, energetic trapped particles, cosmic rays, and neutrons-often activates these materials, and any improvement in sensitivity as a result of improved energy resolution could be offset by the additional background due to activation. The purpose of this work was to measure potential backgrounds due to trapped and cosmic-ray proton-induced activation in the new materials: SrI 2 :Eu (SrI), 7 Li-enriched Cs 2 LiYCl 6 :Ce (CLYC-7), Cs 2 LiLaBr 6 :Ce (CLLB), Cs 2 LiLa(Br,Cl) 6 :Ce (CLLBC), Tl 2 LiYCl 6 :Ce (TLYC), and Gd 3 (Al,Ga) 5 O 12 :Ce (GAGG). Using a large-diameter 64-MeV proton beam, detectors were irradiated with a total dose of 100 rad (Si), roughly equivalent to the annual dose in a typical low earth orbit. Measurements were made with a single 100% relative efficiency high-purity germanium (HPGe) (0.05-3 MeV) and the irradiated detector. Two multichannel analyzers (MCAs) operating in the event mode were used to collect the data. Time-tagged events were processed into various spectral integration times for analysis, and characteristic gamma-ray energies and decay times were used to identify activation products. Most of the identified activation products were the result of (p, xn) reactions, with a few exceptions. This work identifies the primary radioisotopes generated by energetic proton activation in six different scintillator materials.