[en] In this study, a search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment’s unique configuration of multiple baselines from six 2.9 ${\mathrm{GW}}_{\mathrm{th}}$ nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the ${10}^{-3}{\mathrm{eV}}^2<\mathrm{\Delta }{m}_{41}^2<0.3{\mathrm{eV}}^2$ range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on ${\sin }^{2}2{\theta }_{14}$ cover the ${10}^{-3}{\mathrm{eV}}^2\lesssim \mathrm{\Delta }{m}_{41}^2\lesssim 0.1{\mathrm{eV}}^2$ region, which was largely unexplored.

[en] A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (${\overline{\nu }}_e$) from six $2.9{\mathrm{GW}}_{\mathrm{th}}$ reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude ${\sin }^{2}2{\theta }_{13}=0.090_{-0.009}^{+0.008}$ and the first direct measurement of the ${\overline{\nu }}_e$ mass-squared difference $\mathrm{\Delta }{m}_{ee}^2=(2.59_{-0.20}^{+0.19})\times {10}^{-3}{\mathrm{e}\mathrm{V}}^2$ is obtained using the observed ${\overline{\nu }}_e$ rates and energy spectra in a three-neutrino framework. This value of $\mathrm{\Delta }{m}_{ee}^2$ is consistent with $\mathrm{\Delta }{m}_{\mu \mu }^2$ measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

[en] In this paper we describe a new type of scintillating liquid based on water. We describe the concept, preparation, and properties of this liquid, and how it could be used for a very large, but economical detector. The applications of such a detector range from fundamental physics such as nucleon decay and neutrino physics to physics with broader application such as neutron detection. We briefly describe the scientific requirements of these applications, and how they can be satisfied by the new material.

[en] Tellurium-130 has the highest natural abundance of any double-beta decay isotopes. Recently it has been developed as a promising candidate for loading in liquid scintillator to explore the Majorana or Dirac nature of the neutrino through a search for neutrinoless double beta decay (0νββ). To this end, procedures have been developed to transfer tellurium ions into the organic liquid by a water-based loading technology. However, traces of naturally occurring radioactivity and cosmic-ray induced isotopes introduced into the scintillator with tellurium could produce undesirable contaminations in the "1"3"0Te 0νββ region. Measurements using various elemental spikes prepared from different chemical forms indicate that the uses of self-scavenging as well as acid and thermal recrystallization prior to the preparation of a tellurium-loaded liquid scintillator can deplete U and Th and several cosmic-activated isotopes from Te feedstock by a factor of 10"2–10"3 in a single pass. The process is also found to improve the optical transmission in the blue region, sensible to the photomultiplier tube, by removing traces of colored impurities. In addition to the scintillator-based experiments, this cleansing scheme has potential applications to the production of radiopure tellurium crystals for other rare-event experiments

[en] The Daya Bay Reactor Neutrino Experiment was designed to achieve a sensitivity on the value of sin²2θ₁₃ to better than 0.01 at 90% CL. The experiment consists of eight antineutrino detectors installed underground at different baselines from six nuclear reactors. With data collected with six antineutrino detectors for 55 days, Daya Bay announced the discovery of a non-zero value for sin²2θ₁₃ with a significance of 5.2 standard deviations in March 2012. The most recent analysis with 139 days of data acquired in a six-detector configuration yields sin²2θ₁₃=0.089±0.010(stat.)±0.005(syst.), which is the most precise measurement of sin²2θ₁₃ to date

[en] The Daya Bay Reactor Neutrino Experiment is designed to determine precisely the neutrino mixing angle θ₁₃ with a sensitivity better than 0.01 in the parameter sin²2θ₁₃ at the 90% confidence level. To achieve this goal, the collaboration will build eight functionally identical antineutrino detectors. The first two detectors have been constructed, installed and commissioned in Experimental Hall 1, with steady data-taking beginning September 23, 2011. A comparison of the data collected over the subsequent three months indicates that the detectors are functionally identical, and that detector-related systematic uncertainties are smaller than requirements.

[en] The Daya Bay experiment consists of functionally identical antineutrino detectors immersed in pools of ultrapure water in three well-separated underground experimental halls near two nuclear reactor complexes. These pools serve both as shields against natural, low-energy radiation, and as water Cherenkov detectors that efficiently detect cosmic muons using arrays of photomultiplier tubes. Each pool is covered by a plane of resistive plate chambers as an additional means of detecting muons. Design, construction, operation, and performance of these muon detectors are described