The detector system of the Daya Bay reactor neutrino experiment

Abstract

The Daya Bay experiment was the first to report simultaneous measurements of reactor antineutrinos at multiple baselines leading to the discovery ofν e oscillations over km-baselines. Subsequent data has provided the world's most precise measurement of sin 2 2θ 13 and the effective mass splitting ∆m 2 ee . The experiment is located in Daya Bay, China where the cluster of six nuclear reactors is among the world's most prolific sources of electron antineutrinos. Multiple antineutrino detectors are deployed in three underground water pools at different distances from the reactor cores to search for deviations in the antineutrino rate and energy spectrum due to neutrino mixing. Instrumented with photomultiplier tubes, the water pools serve as shielding against natural radioactivity from the surrounding rock and provide efficient muon tagging. Arrays of resistive plate chambers over the top of each pool provide additional muon detection. The antineutrino detectors were specifically designed for measurements of the antineutrino flux with minimal systematic uncertainty. Relative detector efficiencies between the near and far detectors are known to better than 0.2%. With the unblinding of the final two detectors' baselines and target masses, a complete description and comparison of the eight antineutrino detectors can now be presented. This paper describes the Daya Bay detector systems, consisting of eight antineutrino detectors in three instrumented water pools in three underground halls, and their operation through the first year of eight detector data-taking.

Measurement of electron antineutrino oscillation based on 1230 days of operation of the Daya Bay experiment

“…These changes in liquid level were consistent with a slow leak of 50 l of LS into the 42,800 l MO region of this detector over this two year period (see the description given in section 9. 3 of [30]). An increase in the absorbance of short-wavelength light in the MO and an increase in the amount of light detected for muons which traversed the MO verified that a leak had occurred.…”

“…These basic characteristics have yielded measurements of sin 2 2θ 13 with ∼4% precision and jΔm 2 ee j with ∼3% precision, as discussed in this paper. This section provides an abbreviated description of the Daya Bay experiment, while a more detailed description is given in [30].…”

“…Subsequent temperature-and pressure-related variation of the AD target masses was determined to within 1.5 l (<0.01%) via precision monitoring of the GdLS levels in the liquid overflow tanks of each detector (see Fig. 23 of [30]). Few-mm fluctuations in level were seen during operation, which corresponded to ∼6 kg (∼0.03%) variations in target mass.…”

Study of the wave packet treatment of neutrino oscillation at Daya Bay

“…More details on the experimental setup are contained in Refs. [49][50][51][52]. The studies in this paper are based on data acquired in the 6-AD period when there were two ADs in EH1, one AD in EH2 and 3 ADs in EH3, with the addition of the 8-AD period from October 2012 to November 2013, a total of 621 days.…”

“…Details can be found in Refs. [49,52]. The analysis was done with four unconstrained parameters σ rel , Δm 2 32 , sin 2 2θ 13 and reactor flux normalization N .…”