New Results of the DANSS Experiment Taking into Account the Absolute Antineutrino Counting Depending on Distance

Abstract

The DANSS detector, i.e., a scintillation detector with a sensitive volume of 1 m3, is installed at the Kalinin nuclear power plant under the reactor core on a mobile stage. The distance from the detector center to the reactor center is varied from 10.9 to 12.9 m. The detector records about 5000 events of inverse beta decay per day a background level from cosmic muons of the order of two percent. The analysis on the search for sterile neutrino taking into account the count rate of antineutrino events is described. The final ratio of the observed rate of absolute DANSS counting to that predicted based on the Huber and Mueller model was 0.98 ± 0.04. New results on the search for sterile neutrino based on 7 million of antineutrino events are presented. When using the conservative estimate of 7% for the total systematic uncertainty in the absolute count rate, the limits in the parameter space of the hypothetical sterile neutrino are determined. In particular, for high (≳10 eV2) parameters \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta m_{{41}}^{2}$$\\end{document}, the values of \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${{\\sin }^{2}}2{{\ heta }_{{ee}}} > 0.26$$\\end{document} are excluded at the 90% confidence level.