Light Yield Non-Proportionality and Energy Resolution of Praseodymium Doped LuAG Scintillator

Scintillation properties of praseodymium doped LuAG have been investigated. The crystal is a dense (6.7 g/cm³) scintillator with a short decay time around 20 ns and wavelength emission spectrum peaked at 310 nm. The tested sample was 10 mm times 10 mm times 5 mm cuboid, polished on all surfaces. The dopant concentration amounts to 0.23 mo1%. A light yield of 16000plusmn1600 ph/MeV was measured using high sensitivity (13.7 muA/1mF) Photonis photomultiplier (PMT) XP5500B. High quantum efficiency of this PMT (35%) allowed us to register 5600plusmn400 phe/MeV using 12 mus shaping time in the spectroscopy amplifier. The measured energy resolution was equal to 5.0plusmn0.1%. Response of LuAG:Pr to gamma-rays was found to be proportional over wide energy range. Deviation from proportionality does not exceed 10% at 16.6 keV. This results in good intrinsic energy resolution of LuAG:Pr amounting to 3.0plusmn0.3%, measured with 662 keV gamma-rays from ¹³⁷Cs.