Gamma-Ray Responses of Pr:LuYAP and Pr:YAP Scintillators

Pr³⁺ doped LuYAP crystal was grown by the Czochralski method with 1 inch diameter and 10 cm length. In order to compare scintillation characteristics, Pr³⁺ doped YAP crystal was also grown by the micro-pulling-down method. Absorption spectra of them were measured and Pr³⁺ 4f → 4f5d and 4f2 → 4f absorption lines were observed at 230,470, and 600 nm, respectively. In photoluminescence measurements, here excited by Xe lamp pulse of wavelength around 223,250 and 280 nm emission lines due to Pr³⁺ 4f5d → 4f transition were detected. When coupled with PMT R7600 and irradiated by gamma-rays, gamma-ray induced light yields were estimated as 1900 ph/MeV for Pr: LuYAP and 5600 ph/MeV for Pr: YAP. In both crystals, light yield non-proportionality and energy resolution were investigated by individual lines in the gamma-ray energy range from 59.5 keV to 1408 keV. The gamma-ray excited decay time constants turned out to be 9.8 ns for Pr:LuYAP and 9.0 ns for Pr:YAP.