Exploring Large-Volume GAGG Scintillators for use in MeV Gamma-Ray Astrophysics

Abstract

Gamma-ray astrophysics in the MeV band is an exciting field in astronomy due to its potential for multi-messenger astrophysics. It has, however, remained under-explored when compared to other wavelengths. One reason for this observational gap is the difficulties with measuring these high-energy photons and the requirement of large amounts of detection material. In this work, we investigate the usage of large-volume GAGG scintillators for use as a calorimeter in future MeV telescopes. We developed a $5\times 5$ array calorimeter utilizing $1\times 1\times 6{\mathrm{cm}}^3$ GAGG crystals with onsemi C-series SiPM readout. We tested the calorimeter at the High Intensity Gamma-ray Facility (HIGS) with monoenergetic beams ranging from $2-25\mathrm{MeV}$. Finally, we also investigate larger $1\times 1\times 8{\mathrm{cm}}^3$ crystals and characterize their response across their depth when their surface treatment is either polished or frosted.