Performance evaluation of GYGAG crystals for neutrinoless double beta decay search

Abstract Neutrinoless double beta decay (0νββ) is a crucial for confirming neutrinos’ Majorana characteristics. Previous searches for 0νββ decay of 160Gd using GSO crystals was conducted, but the sensitivity was limited by background α-rays from radioactive impurities. To distinguish the backgrounds, PSD (Pulse Shape Discrimination) and energy resolution are essential. GAGG (Gd3(Al, Ga)5O12) is a 160Gd-containing crystal that exhibits a higher light yield than GSO and excellent PSD capabilities. GYGAG (Gd3 − xYx(Al, Ga)5O12) is a variant crystal where a portion of Gd is substituted with Yttrium and can have enhanced light yield, motivating its investigation for 0νββ decay searches. In this study, GYGAG crystals with different Yttrium concentrations were fabricated and their energy resolution, pulse shape discrimination capability between α and γ rays, and scintillation timing characteristics were evaluated for applications in 0νββ decay searches. Y substitution enhanced the light yield, and the best energy resolution was achieved for Gd2.5Y0.5Al2Ga3O12. GYGAG exhibited high pulse shape discrimination performance across various yttrium concentrations.