An Improved Measurement of Electron Antineutrino Disappearance at Daya Bay

TL;DR

The Daya Bay experiment precisely measured electron antineutrino disappearance, significantly improving the understanding of the neutrino mixing angle θ13 through data collected over 127 days.

Contribution

It provides a more accurate measurement of the neutrino mixing angle θ13 using multiple detectors at different distances from reactors.

Findings

Measured sin^2 2θ13 = 0.089 ± 0.010 (stat) ± 0.005 (syst)

Observed a ratio of 0.944 ± 0.007 (stat) ± 0.003 (syst) at the far site

Collected data over 127 days with high statistical significance

Abstract

The theory of neutrino oscillations explains changes in neutrino flavor, count rates, and spectra from solar, atmospheric, accelerator, and reactor neutrinos. These oscillations are characterized by three mixing angles and two mass-squared differences. The solar mixing angle, {\theta}_12, and the atmospheric mixing angle, {\theta}_23, have been well measured, but until recently the neutrino mixing angle {\theta}_13 was not well known. The Daya Bay experiment, located northeast of Hong Kong at the Guangdong Nuclear Power Complex in China, has made a precise measurement of electron antineutrino disappearance using six functionally-identical gadolinium-doped liquid scintillator-based detectors at three sites with distances between 364 and 1900 meters from six reactor cores. This proceeding describes the Daya Bay updated result, using 127 days of good run time collected between December 24, 2011 and May 11, 2012. For the far site, the ratio of the observed number of events to the expected number of events assuming no neutrino oscillation is 0.944 +/- 0.007(stat) +/- 0.003(syst). A fit for {\theta}_13 in the three-neutrino framework yields sin^2 2{\theta}_13 = 0.089 +/- 0.010(stat) +/- 0.005(syst).