Pr-doped gadolinium pyrosilicate, which had a composition of Gd 2 Si 2 O 7 , was synthesized by the floating zone method with different Pr concentrations from 0.1 to 2.0 mol%. After confirming the crystal phase by X-ray diffraction analysis, photoluminescence (PL) and scintillation properties were investigated. PL emission spectra showed a broad emission peak at 340-360 nm due to Pr 3+ 5d-4f transition, and decay times were around 9-12 ns. In X-ray-induced scintillation spectra, we confirmed a similar spectral shape with PL, and scintillation decay times were around 18-29 ns. In the 137 Cs γ-ray-irradiated pulse height measurement, the 1.0% Pr-doped sample had shown the highest scintillation light yield of 2290 ph/MeV among the present samples. In the same setup, we also used different γ-ray sources to check the energy response linearity. Finally, energy resolution as a function of γ-ray energy was investigated.

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Lanthanum and lutetium pyrosilicate (La 2 Si 2 O 7 and Lu 2 Si 2 O 7 , respectively) single crystals with a Tm doping concentration of 2.0% were successfully synthesized by the floating-zone method. X-ray diffraction patterns showed a single phase in each compound without the impurity phase. Both their photoluminescence (PL) and scintillation properties were systematically determined in this study, including PL emission, PL decay time, X-ray-induced scintillation spectra, X-ray-induced scintillation decay time, afterglow level, and pulse height spectra. The emission from Tm 3+ 4f-4f transition was observed on both samples as shown by PL emission as well as X-ray-induced scintillation spectra. Under 137 Cs 662 keV γ-ray irradiation, their scintillation light yields were 2340 ph/MeV for Tm-doped Lu 2 Si 2 O 7 and 1440 ph/MeV for Tm-doped La 2 Si 2 O 7 .

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Pr-doped yttrium pyrosilicates Y 2 Si 2 O 7 (YPS) single crystals were synthesized by the floating zone method. Five samples with different Pr concentration from 0.1% to 2.0% were prepared to study optical and scintillation properties. When we measured photoluminescence (PL), the emission due to the 5d-4f transition of Pr 3+ appeared in all the samples at the UV wavelength, and PL decay times were around 4-10 ns. In scintillation properties, all of the samples had the same scintillation emission spectral shape with different intensities, and samples with higher Pr concentration trended to have smaller scintillation decay time than those with lower Pr concentration. Under the 137 Cs γ-rays irradiation, the highest scintillation light yield among the present samples was 6600 ph MeV −1 in Pr 1.0% one. In addition, linearity and energy resolution as a function of γ-ray energy were observed in all the samples. © 2019 The Japan Society of Applied Physics Optical propertiesThe PL quantum yield (QY) was evaluated by Quantaurus-QY (Hamamatsu Photonics C11347-01). The absolute QY was calculated by the following equation, QY = N e /N a , when N e and N a , are the numbers of emission and absorption