Thermal neutron–induced γ-ray background in ¹²⁴Sn

Highlights: • The impact of gamma-ray background due to thermal neutron capture in ¹²⁴Sn for the reason of interest around Q_ββ- (¹²⁴Sn) ∼ 2.291 MeV is discussed. • The measured background due to gamma rays from ¹²⁴Sn (n, γ) in the Q_ββ- (¹²⁴Sn) region, is found to be consitent with simulation within errors. • The present data give an independent measurment of the half-lives of ¹²⁵Sn*($\frac{3}{2}$⁺) and ¹²⁵Sn($\frac{11}{2}$⁻) as 10.01(8) min and 9.63(2) d, respectively. - Abstract: The thermal neutron-induced gamma-ray background in ¹²⁴Sn is investigated in connection with neutrinoless double beta decay (0$\nu \beta \beta$) studies in ¹²⁴Sn. For this purpose, a 99.26$\text{\%}$ enriched ¹²⁴Sn sample was irradiated with a thermal neutron fluence of $3\times$10¹⁵/cm² in the Dhruva reactor at the Bhabha Atomic Research Centre, Mumbai. The gamma ray spectra of the irradiated sample were measured in a low background counting setup to study both long-lived and short-lived activities. The present data give an independent measurement of the half-life of ¹²⁵Sn*(${\frac{3}{2}}^{+}$) and ¹²⁵Sn(${\frac{11}{2}}^{-}$) as 10.01(8) min and 9.63(2) d, respectively. The impact of the observed high-energy gamma rays and the residual activity due to ¹²⁵Sb, on the background in the region of interest around the $Q_{\beta \beta }$ value of ¹²⁴Sn ($\sim$2.291 MeV) is discussed.