Antineutrino spectrometer DANSS — 5 years of running

Abstract

Solid scintillator antineutrino detector DANSS is placed on a movable platform below 3.1 GWth industrial reactor of the Kalininskaya Nuclear Power Plant. The distance between the detector and the center of the reactor core is frequently changed in the range 10.9 - 12.9 m. The reactor materials provide overburden of about 50 m.w.e. The one-cubic-meter sensitive volume of the detector is assembled from 2500 polystyrene scintillation strips and surrounded by a multilayer passive and active shielding. A dual readout by silicon photo multipliers (individually) and by convention PMTs (in groups of 50 strips) is used to achieve both high detector granularity and low noise trigger.In the position closest to the reactor core up to 5000 inverse beta-decay events per day are collected with cosmic muons induced background below 2%. The talk covers 5 years of the detector operation, observation of fuel evolution and results of our search for light sterile neutrinos. Spectrum and counting rate dependence on the fission fuel composition is clearly observed and agrees with H-M model. No statistically significant signal of short baseline neutrino oscillations observed so far with large portion of oscillation phase space excluded taking into account the improved analysis of systematic errors. The exclusion region at 90% confidence level reaches sin22θ < 8. 10−3 around Δm 2 ∼ 0.9 eV2.