On the response of GdAlO3:Ce powder scintillators

The aim of the present study was to investigate the luminescence efficiency (XLE) of gadolinium aluminum perovskite (GdAlO3:Ce) powder scintillator. This powder phosphor, also known as GAP:Ce scintillator, is a non-hygroscopic material, emitting blue light with short decay time. For the purposes of this study, five scintillating screens with coating thicknesses, 14.7, 31.0, 53.7, 67.2 and 121.1 mg/cm2, were prepared in our laboratory from GdAlO3:Ce powder (Phosphor Technology, Ltd) by sedimentation on silica substrates. The light emitted by the phosphors under investigation was evaluated by performing measurements of the absolute luminescence efficiency (AE), X-ray luminescence efficiency and detector quantum gain (DQG) under X-ray exposure conditions with tube voltages ranging from 50 to 140 kV. The quantum detection efficiency (QDE) and energy absorption efficiency (EAE) were also evaluated. The spectral compatibility of GdAlO3:Ce, with various existing optical detectors, was investigated after emission spectra measurements. A theoretical model, describing radiation and light transfer, was used to fit experimental AE data. This has allowed the estimation of optical attenuation coefficients of the scintillator. GdAlO3:Ce exhibited higher QDE and EAE values, compared to aluminium perovskite (YAlO3:Ce) but lower absolute efficiency values. Absolute efficiency was found to increase with increasing X-ray tube voltage, although for values higher than 120 kVp a decrease was observed. -- Highlights: • The X-ray quantum detection efficiency and energy absorption efficiency of GdAlO3:Ce powder scintillators were found higher than currently employed materials (aluminum perovskite-YAlO3:Ce) for detection of X-rays. • The peak absolute luminescence efficiency was obtained for the 67.2 mg/cm2 screen at X-ray tube voltages from 100 to 120 kVp. • The absolute luminescence efficiency is lower, compared to YAlO3:Ce, within the energy range under consideration. • The emission spectrum of GdAlO3:Ce screen showed good spectral compatibility with currently used detectors (mainly analogue)