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

Abstract

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 (μ-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 137Cs 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 (photoluminescence, 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.