Crystal growth and scintillation properties of Pr-doped oxyorthosilicate for different concentration

摘要

0.05, 0.1 and 0.25 mol% Pr (with respect to Lu) doped Lu_2SiO_5 (LSO) single crystals were grown by the micro-pulling down ((i-PD) method. The grown crystals were transparent, and a slight segregation of Pr~3+ was observed both in the crystal cross-section and growth direction. Transparency in the visible wavelength range was about 80% in all the crystals. Intense absorptions related with the Pr~(3+) 4f-5d transitions were observed around 230 and 255 nm, and weak absorptions due to the 4f-4f transitions were detected around 450 nm. In radioluminescence spectra, the Pr~(3+) 5d-4f transitions were observed around 275and 310 nm, and emissions due to the 4f-4f transition were observed around 500 nm. In the pulse height analysis using ~(137)Cs gamma-ray excitation, Pr 0.1% doped sample showed the highest light yield of 2,800 ph/MeV. In the decay time measurements using different excitation sources (photo-luminescence, X- and gamma-ray), two different processes related to the 5d-4f emission peaks were found. Fast decay component corresponds to direct excitation of Pr~(3+) (4-6 ns) and slower component (25 ns) reflects the energy migration process from the host lattice to the emission center.