Study on scintillation properties of rare earth (Pr, Nd and Tm) activated Lu₂SiO₅

Rare earth (Pr, Nd and Tm) doped Lu₂SiO₅ (LSO) single crystals were grown by the micro-pulling down (μ-PD) method. The concentrations were added 0.05, 0.10, and 0.25% of Pr, 0.10, 0.25, and 0.50% of Nd, 0.1, 1, 10, and 100% of Tm with respect to Lu, respectively. Optical and radiation measurements were carried out on the samples. Pr samples have a transparency of about 80% in visible wavelength range in all crystals. Intense absorptions related with Pr³⁺ 4f-5d transitions were observed peaking around 230, 255 nm, and weak absorptions due to 4f-4f transitions were detected around 450 nm. In radio luminescence spectra, emissions due to Pr³⁺ 5d-4f transition were observed peaking around 275 nm, 310 nm, and emissions due to 4f-4f transition were observed peaking around 500 nm. By pulse height analysis with gamma-ray excitation using ¹³⁷Cs, Pr 0.1% doped sample showed the highest light yield of 2,800ph/MeV. In decay time measurements using different excitation energy (photo-luminescence, X- and gamma-ray), two different processes of 5d-4f emissions were found. Fast decay component corresponds to direct excitation of Pr³⁺ (4-6 ns) and slower component (25 ns) reflects the energy migration process from the host lattice to the emission center.