Development of a radiation detector using a silicon photomultiplier and large Ce-doped Gd-Al-Ga-grant scintillator for gamma spectroscopy observations of radioactivation in a linear accelerator

In this study, a radiation detector based on a silicon photomultiplier (SiPM) and large Ce-doped Gd-Al-Ga-grant (Ce:GAGG) scintillator was developed for the gamma spectroscopy observations of radioactivation from linear accelerators (LINACs). The calibration of the detector demonstrated a high energy resolution of 15.89% at 122 keV (gamma-ray emission energy of Co-57), 7.04% at 356 keV (gamma-ray emission energy of 133Ba), 6.17% at 511 keV (gamma-ray emission energy of Na-22), and 5.39% at 662 keV (gamma-ray emission energy of Cs-137). These results indicate that the detector employing a larger Ce:GAGG scintillator provides a higher detection efficiency while maintaining superior energy resolution compared to conventional radiation detectors that use smaller Ce:GAGG scintillators. Furthermore, the energy spectrum measurement of the LINAC revealed detection of neutron and gamma peaks of W-187 and Mn-56, as well as annihilation peaks. Although the energy resolution of the detector was inferior compared to an HPGe detector, it was able to measure similar energy peaks. Therefore, the radiation detector developed in this study, which is characterized by its low cost, decent energy resolution, and high detection efficiency, may be useful for obtaining radiation measurements during the disposal of LINACs.