Chalerm Wanarak

Scintillation Properties of LuAG:Ce, YAG:Ce and LYSO:Ce Crystals for Gamma-Ray Detection

The scintillation properties of LuAG:Ce and YAG:Ce crystals were compared with LYSO:Ce crystal under ¿ -ray excitation. Light yield non-proportionality and energy resolution were measured with a Photonis XP5500B PMT. The energy resolution, obtained in this work for 662 keV ¿ -rays, was 6.7, 7.0 and 8.7%, respectively, for LuAG:Ce, YAG:Ce and LYSO:Ce detectors. The values reflect the influence of the light yield non-proportionality on the measured energy resolution. A fast component in the scintillation decay of LuAG:Ce crystal is faster than that of the YAG:Ce crystal, whereas the relative intensity of a fast component for YAG:Ce crystal is higher than that of LuAG:Ce crystal. The coincidence time resolution, obtained in this work for 511 keV annihilation quanta, was 660, 583 and 222 ps, respectively, for YAG:Ce, LuAG:Ce and LYSO:Ce detectors in coincidence experiment together with a BaF2 detector. Time resolution was also discussed in terms of a number of photoelectrons and decay time of the light pulse.

Luminescence properties and scintillation response in Ce3+-doped Y2Gd1Al5-xGaxO12 (x = 2, 3, 4) single crystals

The compositional dependence of luminescence properties and scintillation response were investigated in Ce3+-doped Y2Gd1Al5-xGaxO12 (x = 2, 3, 4) single crystals. The Gd3+ → Ce3+ energy transfer was evidenced by photoluminescence excitation spectra of Ce3+ emission. With increasing Ga content in the garnet host, the Ce3+ luminescence from the lowest 5d level (5d1) is shifted toward higher energy due to the decrease in the crystal field splitting of the 5d levels. Light yield (LY) and its dependence on the amplifier shaping time were measured under excitation with γ-rays. High LY value of ∼38 000 ph/MeV was obtained for a Y2Gd1Al3Ga2O12:Ce sample. Scintillation decay was measured with an extended dynamical and temporal scale under the nanosecond pulse soft X-ray excitation. The decrease of both LY value and relative contribution of slower decay component in the scintillation response was observed with increasing Ga content in the garnet host.

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.

Lu1.8Y0.2SiO5:Ce and LaCl3:Ce Scintillators for Gamma-Ray Detection

The scintillation properties of Lu1.8Y0.2SiO5:Ce (LYSO:Ce) and LaCl3:Ce scintillators were studied under g-ray excitation. For 662 keV g-rays (137Cs source), energy resolution of 4.5% obtained for LaCl3:Ce coupled to XP5200B PMT is much better than that of 8.2% for LYSO:Ce. The estimated photofraction of 26.1% at 662 keV for LYSO:Ce is higher than that of 15.7 % for LaCl3: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. The coincidence timing resolution, obtained in this work for 511 keV annihilation quanta, was 222 and 229 ps, respectively, for LYSO:Ce – and LaCl3:Ce – based detectors in coincidence with a BaF2 detector.

Comparison of Lu3Al5O12:Ce and LaBr3:Ce Scintillators in Gamma-Ray Spectrometry

The performances of Ce-doped Lu3Al5O12 (LuAG:Ce) and LaBr3 (LaBr3:Ce) scintillators were compared for γ-ray detection using photomultiplier tube ( XP5500B PMT) readout. For 662 keV γ-rays (137Cs source), an energy resolution of 3.5% obtained for LaBr3:Ce is much better than that of 6.7% obtained for LuAG:Ce, while the estimated photofraction of 28.0% for LuAG:Ce is higher than that of 16.2% for LaBr3:Ce. The light yield non-proportionality and energy resolution versus γ-ray energy were measured and the intrinsic resolution of the crystals was calculated. The coincidence timing resolution, obtained in this work for 511 keV annihilation quanta, was 583 ps and 204 ps, respectively, for LuAG:Ce –BaF2 and LaBr3:Ce – BaF2 detectors.