Study of neutrino and dark matter by high sensitivity ββ, γ and X ray spectrometer ELEGANTS

Abstract

Nuclear and particle rare decay and weak processes were studied by high sensitivity β-γ and X ray spectrometer ELEGANTS V. A finite value of half life for the two neutrino double beta decay of 100Mo ( T 1 2 2ν = 1.15 −0.20 +0.30 × 10 19 yr ) and the lower limit for neutrino less double beta decay ( T 1 2 0ν > 7 × 10 21 yr ) for 100Mo were obtained. Double beta decays of 116Cd has also been studied. The preliminaly half life for the two neutrino double beta decay ( T 1 2 2ν = 2.6 −0.6 +1.3 × 10 19 yr ) and the lower limit for neutrino less double beta decay ( T 1 2 0ν > 1.1 × 10 21 yr ) were obtained. The large volume NaI(Tl) scintillators in ELEGANTS V have been applied to search for cosmic cold dark matter candidates. The elastic scattering and inelastic scattering of dark matter and the nuclei in the NaI(Tl) scintillator were studied. The low back ground (⋍5/day/keV/kg) and low noise (⋍5keV) experiment was successfully done and stringent limit on the local density of dark matter candidates was given.