Effects of Neutron Irradiations in Various Crystal Samples of Large Size for Future Crystal Calorimeter

In this paper, we report an investigation on the radiation damage effects induced by neutrons in large size crystal scintillator: BGO, CeF_3, LYSO:Ce and PWO. The irradiations were carried out by using fast neutrons from one ^(241)Am-Be and two ^(252)Cf sources. The optical and scintillation properties of these samples, including UV excitation and emission spectra, longitudinal transmission, light output, decay kinetics and light response uniformity, were measured before and after the irradiations. The neutron induced photo-current was also measured, and was used to estimate the readout noise under the neutron flux expected by an electromagnetic calorimeter at a very severe radiation environment. Because of its high light output and excellent radiation resistance LYSO:Ce crystal is found to have the smallest neutron induced readout noise as compared to other large size crystals, indicating it is a good candidate material for a future crystal calorimeter in a severe radiation environment.