Lithium aluminate crystals as scintillator for thermal neutron detection

Undoped and Cu ⁺-doped lithium aluminate LiAlO ₂ singe crystals have been grown using micro-pulling down (μ-PD) technique. After cutting and polishing, optical properties and scintillation characteristics of the crystals were examined. From the transmittance measurements, Cu ⁺-doped crystal showed absorption band around 270 nm, which is corresponding to the transition between Cu ⁺ 3d ¹⁰ and 3 d ⁹ 4s states. Ultra violet emission peak appeared around 360 nm under 270 nm excitation. The emission decay time was calculated to be about 17.3 μ s. ²⁴¹ Am 5.5 MeV alpha-ray excited radioluminescence spectra exhibited intense luminescence band at 360 nm due to the Cu ⁺3d ⁹4s-3d ¹⁰ transitions. By the pulse height spectra ²⁵² Cf neutron source excitation, the scintillation light output of Cu ⁺-doped LiAlO ₂ was found to be about 8700 ph/n.