Basic optical properties and radiation responses of undoped, Tm 3+ 1.0% and 2.0% activated Ca3(BO3)2 (CBO) crystalline scintillator prepared by the micro-pulling down (μ-PD) method are reported. Tm3+: CBO crystals showed three weak absorption bands around 190, 260 and 350 nm, owing to the Tm3+ 4f-4f transition. Strong blue luminescence peaks at 360 and 460 nm which are ascribed to the 1D2-3H6 and 1D 2-3F4 transitions of Tm3+ respectively were observed under 241Am 5.5 MeV α-ray excitation. The scintillation light yield of 2.0% Tm3+-doped CBO crystal was evaluated to be about 250 ph/n from the 252Cf excited pulse height spectrum.
- Tm 4f-4f transition
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