Precision Measurement of Reactor Antineutrino Oscillation at Kilometer-Scale Baselines by Daya Bay

Abstract

We present a new determination of the smallest neutrino mixing angle 013 and the mass-squared difference Delta m232 using a final sample of 5.55 x 106 inverse beta-decay (IBD) candidates with the final-state neutron captured on gadolinium. This sample is selected from the complete dataset obtained by the Daya Bay reactor neutrino experiment in 3158 days of operation. Compared to the previous Daya Bay results, selection of IBD candidates has been optimized, energy calibration refined, and treatment of back-grounds further improved. The resulting oscillation parameters are sin22013 = 0.0851 +/- 0.0024, Delta m232 = (2.466 +/- 0.060) x 10-3 eV2 for the normal mass ordering or Delta m232 = -(2.571 +/- 0.060) x 10-3 eV2 for the inverted mass ordering.