Search for sterile neutrinos at the DANSS experiment

AbstraktAbstract

DANSS is a highly segmented 1 m3 plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1 GW(th) reactor of the Kalinin Nuclear Power Plant 350 km NW from Moscow. The distance to the core is varied on-line from 10.7 m to 12.7 m. The reactor building provides about 50 m water-equivalent shielding against the cosmic background. DANSS detects almost 5000 (nu) over tilde (e) per day at the closest position with the cosmic background less than 3%. The inverse beta decay process is used to detect (nu) over tilde (e). Sterile neutrinos are searched for assuming the 4 nu model (3 active and 1 sterile nu). The exclusion area in the Delta m(14)(2), sin(2) 2 theta(14) plane is obtained using a ratio of positron energy spectra collected at different distances. Therefore results do not depend on the shape and normalization of the reactor (nu) over tilde (e) spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at three different distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to sin(2) 2 theta(14) < 0.01 in the most sensitive region. (C) 2018 The Authors. Published by Elsevier B.V.

DANSS is a highly segmented 1 m3 plastic scintillator detector. Its 2500 one meter long scintillator strips have a Gd-loaded reflective cover. The DANSS detector is placed under an industrial 3.1 GW(th) reactor of the Kalinin Nuclear Power Plant 350 km NW from Moscow. The distance to the core is varied on-line from 10.7 m to 12.7 m. The reactor building provides about 50 m water-equivalent shielding against the cosmic background. DANSS detects almost 5000 (nu) over tilde (e) per day at the closest position with the cosmic background less than 3%. The inverse beta decay process is used to detect (nu) over tilde (e). Sterile neutrinos are searched for assuming the 4 nu model (3 active and 1 sterile nu). The exclusion area in the Delta m(14)(2), sin(2) 2 theta(14) plane is obtained using a ratio of positron energy spectra collected at different distances. Therefore results do not depend on the shape and normalization of the reactor (nu) over tilde (e) spectrum, as well as on the detector efficiency. Results are based on 966 thousand antineutrino events collected at three different distances from the reactor core. The excluded area covers a wide range of the sterile neutrino parameters up to sin(2) 2 theta(14) < 0.01 in the most sensitive region. (C) 2018 The Authors. Published by Elsevier B.V.