Estimation of neutron dose from n-induced activity in nat Fe and nat Zr

Neutron transmutation doped (NTD) Ge thermistors will be used as low temperature sensors (in mK range) in the cryogenic Tin bolometer, The India-based TIN detector (TIN.TIN). For this purpose, semiconductor grade Ge wafers are irradiated at Dhruva reactor, BARC [1]. In order to obtain an independent estimate of the thermal and fast neutron flux, Zr and Fe samples were used together with the Ge samples in the irradiation run of March, 2015. The irradiated samples have been studied in the Tifr Low background Experimental Setup (TiLES) [2] at TIFR. The reaction products of thermal and fast neutron induced reactions in Fe and Zr were identified using characteristic gamma-rays. The half-lives of the observed -rays were also measured for unambiguous identification of the radionuclides. The thermal neutron flux is estimated from the Zr activity. The ratio of thermal to fast neutron flux is estimated from (n,γ),(n,p) and (n,α) reactions in Fe.