Independent Measurement of Theta13 via Neutron Capture on Hydrogen at Daya Bay

TL;DR

This paper reports a new independent measurement of the neutrino mixing angle theta13 at Daya Bay using neutron capture on hydrogen, providing a systematic-uncertainty-independent result that improves the overall precision of theta13 measurement.

Contribution

It introduces a novel measurement method for theta13 via neutron capture on hydrogen, independent of gadolinium-based detection, enhancing the accuracy of neutrino oscillation parameters.

Findings

Measured sin^2(2theta13) as 0.083 ± 0.018 from hydrogen capture data.

Combined result yields sin^2(2theta13) = 0.089 ± 0.008.

Demonstrates the viability of hydrogen capture as an independent measurement channel.

Abstract

A new measurement of the $\theta_{13}$ mixing angle has been obtained at the Daya Bay Reactor Neutrino Experiment via the detection of inverse beta decays tagged by neutron capture on hydrogen. The antineutrino events for hydrogen capture are distinct from those for gadolinium capture with largely different systematic uncertainties, allowing a determination independent of the gadolinium-capture result and an improvement on the precision of $\theta_{13}$ measurement. With a 217-day antineutrino data set obtained with six antineutrino detectors and from six 2.9 GW$_{th}$ reactors, the rate deficit observed at the far hall is interpreted as $\sin^22\theta_{13}=0.083\pm0.018$ in the three-flavor oscillation model. When combined with the gadolinium-capture result from Daya Bay, we obtain $\sin^22\theta_{13}=0.089\pm0.008$ as the final result for the six-antineutrino-detector configuration of the Daya Bay experiment.