Radiation Damage in 20-cm Long LYSO:Ce and BaF₂:Y Crystals

Inorganic scintillators are widely used in high-energy physics (HEP) experiments. Bright and fast cerium-doped lutetium yttrium oxyorthosilicate ( $\text {Lu}_{2(1-x)}\text {Y}_{2x}\text {SiO}_{{5}}\text {:Ce}$ or LYSO:Ce or LYSO) crystals are being used to construct the compact muon solenoid (CMS) barrel timing layer (BTL) detector at the high-luminosity large hadron collider (HL-LHC), where up to 2.5-Mrad ionization dose, $1.7 \times 10^{13}$ charged hadrons/cm2, and $2 \times 10^{14}~\text {n}_{\text {eq}}/\text {cm}^{2}$ are expected. With an ultrafast scintillation of less than 0.6- ns decay time and a suppressed slow component, yttrium-doped barium fluoride (BaF2:Y) crystal is a promising ultrafast inorganic scintillator for future HEP time of flight and calorimeter applications at the energy and intensity frontiers. The 20-cm-long LYSO:Ce and BaF2:Y crystals were irradiated by 800-MeV proton beam at the blue room of Los Alamos Neutron Science Center (LANSCE) up to $7.5 \times 10^{15}$ p/cm2. We report on the degradation of their optical and scintillation properties.