Work

Nonproportional Response of a GAGG Scintillator to Beta and Gamma Radiation over a Wide Energy Range in PIKACHU

Year: 2026

Type: article

Abstract: The nonproportional response of scintillation light yield for sub-MeV radiation is a well-known characteristic of inorganic scintillators. In the PIKACHU (Pure Inorganic scintillator experiment in KAmioka for CHallenging Underground sciences) experiment, a precise understanding of the nonproportional response of the GAGG ($\mathrm{Ce:Gd_3Al_2Ga_3O_{12}}$) scintillator is essential for background modeling. In this study, the nonproportional response of the GAGG scintillator was evaluated for both $\beta$ and $\gamma$ rays. The response for $\beta$ rays was measured using the Compton coincidence technique with a germanium detector, while that for $\gamma$ rays was evaluated using several monoenergetic $\gamma$-ray sources. The measurement results showed different responses for $\beta$ and $\gamma$ rays, with a stronger nonproportional response for $\gamma$ rays than for $\beta$ rays over the energy range of 50–2614 keV. The background model incorporating the measured nonproportional responses reproduced the measured background spectra more accurately compared with the model without the nonproportional response correction. These results demonstrate the importance of precise evaluation of the nonproportional response of the GAGG scintillator, which is essential not only for background modeling in the PIKACHU experiment but also for accurate energy calibration in scintillator-based experiments.

Source: Progress of Theoretical and Experimental Physics

DOI: 10.1093/ptep/ptag164