Akapong Phunpueok

Luminescence and Scintillation Properties of Ce-Doped LYSO and YSO Crystals

The luminescence and gamma-ray detection properties of the new cerium-doped rare-earth scintillator lutetium-yttrium oxyorthosilicate ( Lu1.95Y0.05SiO5:Ce, LYSO:Ce) were investigated and compared to those of cerium-doped yttrium oxyorthosilicate ( Y2SiO5:Ce, YSO:Ce) crystal. The light yield and energy resolution were measured using photomultiplier tube (PMT) readout. The non-proportionality of the light yield and energy resolution versus γ-ray energy were measured and the intrinsic resolution of the crystals was calculated. In spite of significant progress in light yield and luminescence properties, the energy resolution of LYSO:Ce appears to still suffer from an excess variance in the number of scintillation photons. The mass attenuation coefficient of LYSO:Ce and YSO:Ce for 662 keV gamma rays was also measured by transmission method and compared with the theoretical values calculated by WinXCom program.

Luminescence and Scintillation Properties of Ce-Doped YAP and LuYAP Crystals

The luminescence and gamma-ray detection properties of cerium-doped scintillators, namely, Lu0.3Y0.7AlO3:Ce (Lu0.3Y0.7AP:Ce), Lu0.7Y0.3AlO3:Ce (Lu0.7Y0.3AP:Ce ), and YAlO3:Ce (YAP:Ce) were investigated. UV excitation and emission spectra of studied crystals were compared. The light yield and energy resolution were measured using photomultiplier tube (PMT) readout. The light yield non-proportionality and energy resolution versus gamma-ray energy were measured and the intrinsic resolution of the crystals was determined after correcting the measured energy resolution for PMT statistics. For 662 keV gamma rays (137Cs source), YAP: Ce showed the highest light yield of 28,500 ph/MeV and the best energy resolution of 4.4 % , while its photofraction is worst.

Light Yield Non-Proportionality and Energy Resolution of Lu1.8Y0.2SiO5:Ce and LaCl3:Ce Scintillation Crystals

The scintillation response of Lu1.8Y0.2SiO5:Ce (LYSO:Ce) and LaCl3:Ce scintillators were compared under g-ray excitation using photomultiplier tube (PMT) readout. For 662 keV g-rays (137Cs source), energy resolution of 4.5±0.2% obtained for LaCl3:Ce coupled to XP5200B PMT is much better than that of 8.2±0.4% for LYSO:Ce. The non-proportionality of the light yield and energy resolution versus g-ray energy were measured and the intrinsic resolution of the crystals was calculated. Special attention was devoted to the correlation between intrinsic resolution and non-proportional response of scintillators.

Comparison of Lu0.7Y0.3AP:Ce and Bi4Ge3O12 Scintillators in Gamma Ray Spectrometry

The scintillation response of Lu0.7Y0.3AP:Ce and Bi4Ge3O12 scintillation crystals have been compared using photomultiplier tube readout for photon energies ranging from 22.1 to 1274.5 keV. Lu0.7Y0.3AP:Ce showed a light yield non-proportionality of about 20% upon lowering energy from 1,274.5 to 22.1 keV, which is better than that of about 39% obtained for Bi4Ge3O12. Lu0.7Y0.3AP:Ce showed the light yield of 13,400 ph/MeV and energy resolution of about 8 % for 662 keV gamma rays from a 137Cs source. The photofraction of Bi4Ge3O12 is better than that of Lu0.7Y0.3AP:Ce. The intrinsic resolution of the crystals versus energy of gamma rays has been determined after correcting the measured energy resolution for photomultiplier tube statistics.