Characterization of GAGG(Ce) scintillator crystal detectors for gamma ray measurements

Abstract

A FAPESP Regular Project n. 2016/04612-9 is under devellopment at the DFN-IFUSP, coordinated by the supervisor, involving the construction and use of a gamma spectrometer for experiments to measure nuclear reaction mechanisms by the particle-gamma coincidence techique. In this project new generation inorganic scintillators, such as GAGG(Ce) and LYSO(Ce) crystals will be used as gamma detectors. In the present project the main objective is the characterization of the response of GAGG(Ce) crystals of 12.4x12.4x40mm³ size coupled to Silicon Photomultipliers (SiPM). The GAGG(Ce) crystal, in spit of its better intrinsic energy resolution, in contrast to the LYSO(Ce) one, presents high self absorption of the scintillation. As a consequence, the time and energy resolutions for low energy gamma rays (~250 keV and below) is poor. The coupling of SiPMs at both square sides of the crystal is planned to increase light collection, improving resolution, and simultaneously obtaining position sensitivity to the point of interaction inside the crystal. Tests with calibration radiactive gamma sources will be performed. The student will participate in other activities related to the Regular Project.