Lithium Aluminate Crystals as Scintillator for Thermal Neutron Detection

Undoped and Cu⁺-doped lithium aluminate LiAlO₂ 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⁺3d¹⁰ and 3d⁹4s states. Ultra violet emission peak appeared around 360 nm under 270 nm excitation. The emission decay time was calculated to be about 17.3 μs. ²⁴¹Am 5.5 MeV alpha-ray excited radioluminescence spectra exhibited intense luminescence band at 360 nm due to the Cu⁺3d⁹4s-3d¹⁰ transitions. By the pulse height spectra ²⁵²Cf neutron source excitation, the scintillation light output of Cu⁺ -doped LiAlO₂ was found to be about 8700 ph/n.