SCINTILLATION CHARACTERISTICS OF GSO SINGLE-CRYSTAL GROWN UNDER O-2-CONTAINING ATMOSPHERE

A Ce doped Gd2SiO5 (GSO) single crystal is an excellent scintillator featuring a large light output, a short decay constant and a high absorption coefficient. We have investigated dependence of the scintillation characteristics on the growth atmosphere. GSO crystal is usually grown in pure N-2, which due to thermal etching during the growth always roughens the boule surface, inducing some micro-cracks on the surface which often triggers the large crack in the boule. To eliminate this, we first introduced 1 vol% O-2-containing N-2 gas for the growth atmosphere. The resultant boule turned be very smooth in surface, but pale yellow in color and degraded in the scintillation characteristics, To retain these properties. we then introduced an annealing process and found the annealing under pure Nz atmosphere quite effective on the recovery both in color and scintillation properties.