Measurement of electron antineutrino oscillation with 1958 days of operation at Daya Bay

Abstract

We report a measurement of electron antineutrino oscillation from the Daya Bay Reactor Neutrino Experiment with nearly 4 million reactor νe inverse β decay candidates observed over 1958 days of data collection. The installation of a Flash-ADC readout system and a special calibration campaign using different source enclosures reduce uncertainties in the absolute energy calibration to less than 0.5% for visible energies larger than 2 MeV. The uncertainty in the cosmogenic 9 Li and 8 He background is reduced from 45% to 30% in the near detectors. A detailed investigation of the spent nuclear fuel history improves its uncertainty from 100% to 30%. Analysis of the relative νe rates and energy spectra among detectors yields sin 2 2θ13= 0.0856 ± 0.0029 and ∆m 2 32 = (2.471 +0.068 −0.070 )×10 −3 eV 2 assuming the normal hierarchy, and ∆m 2 32 = −(2.575 +0.068 −0.070 )×10 −3 eV 2 assuming the inverted hierarchy.

Consequences of the MSW mechanism with Super-Kamiokande oscillation parameters and of the volume distribution of neutrino sources in the Sun

“…The three-neutrino variant of solar neutrino oscillations, which consists in adding oscillations with a short length and small amplitude, as in the interpretation of a number of experiments with antineutrinos from nearby reactors (see, for example, [9]), does not change the above conclusion. All our considerations remain valid if we change the value of ∆m 2 in equality (4) by an order of magnitude, and the value of sin 2 θ in equality (5) twice.…”

A Decade of Discoveries by the Daya Bay Reactor Neutrino Experiment

“…40 The latest oscillation measurements from Daya Bay are based on nearly four million IBD candidates from 1958 days of data and yield sin 2 2θ 13 = 0.0856 ± 0.0029 and ∆m 2 32 = (2.471 +0.068 −0.070 ) × 10 −3 eV 2 assuming the normal mass hierarchy and ∆m 2 32 = −(2.575 +0.068 −0.070 ) × 10 −3 eV 2 assuming the inverted hierarchy. 41 The measurement of ∆m 2 32 from electron antineutrino disappearance is compared to that from muon neutrino disappearance in Table 2. The precision of the Daya Bay ∆m 2 32 result is comparable or superior to all currently published results.…”

Neutrino Physics with Reactors

“…The unprecedentedly large statistics of antineutrinos detected in current generation experiments, such as Daya Bay's nearly 4 million events [11], allows to study in detail the reactor neutrino flux and energy spectrum shape. The measurements of the absolute reactor neutrino flux exhibit about 5% lower overall rate compared to the reevaluated prediction from 2011 [12,13], which is known as reactor antineutrino anomaly.…”

“…The search for a sterile neutrino is one of the main priorities in the field nowadays, extending beyond reactor neutrinos. [31,11,32,33,34,27,35,29], where the normal neutrino mass hierarchy is assumed.…”

“…The first two have also measured ∆m2 32 . A summary of the latest measurements is shown of Fig.1.Figure1:The latest measurements of the θ 13 mixing angle[11,27,28,16,29,30] and mass squared difference ∆m2 32…”