Efficiency measurement of next generation scintillator GAGG at high energy using the 992keV resonance of the 27Al(p,γ)28Si reaction

Efficiency and peak-to-total ratio of gamma-ray detectors are important for γ-ray detection in reactions with small cross sections. Currently at RIKEN a NaI crystal detector array, DALI2, is used for in-beam gamma experiments. However, due to the small effective Z of the crystal, DALI2 has a low efficiency. Thus, new scintillator crystals with high effective Z are required for efficient findings of gamma-lines. A prospective candidate, cerium doped Gd3Al2Ga3O12, or GAGG(Ce), with a large effective Z was recently developed. The immediate objective of this research is to measure the efficiency of the GAGG crystal especially for high energy gamma rays through a coincidence measurement. To produce these high energy gamma rays, the 12.7MeV resonance of the 27Al(p,γ)28Si reaction was used. The experiment was performed at the RIKEN Pelletron, which provides proton beams up to 3 MeV. 4 GAGG crystals, including the largest GAGG crystal produced so far with a size of (35*35*100mm−3), and 9 DALI2 crystals were arranged around the 27Al target. Different combinations of photomultipliers and GAGG detector geometries were used. In this presentation we show the current status of the data analysis and first results on the performance of GAGG as a detector for high energy gamma rays.