The RENO experiment recently reported the disappearance of reactor electron antineutrinos consistent with neutrino oscillations, with a significance of 4.9 standard deviations. The published ratio of observed to expected number of antineutrinos in the far detector is R=0.920 +-0.009(stat.) +-0.014(syst.) and corresponds to sin^2 2theta13 = 0.113 +-0.013(stat.) +-0.019(syst), using a rate-only analysis. In this letter we reanalyze the data and we find a ratio R=0.903 +-0.01(stat.), leading to sin^2 2theta13 = 0.135. Moreover we show that the sin^2 2theta13 measurement still depend of the prompt high energy bound beyond 4 MeV, contrarily to the expectation based on neutrino oscillation.
The Reactor Experiment for Neutrino Oscillation (RENO) experiment has been taking data using two identical liquid scintillator detectors of 44.5 tons since August 2011. The experiment has observed the disappearance of reactor neutrinos in their interactions with free protons, followed by neutron capture on hydrogen. Based on 1500 live days of data taken with 16.8 GW$_{th}$ reactors at the Hanbit Nuclear Power Plant in Korea, the near (far) detector observes 567690 (90747) electron antineutrino candidate events with a delayed neutron capture on hydrogen. This provides an independent measurement of $theta_{13}$ and a consistency check on the validity of the result from n-Gd data. Furthermore, it provides an important cross-check on the systematic uncertainties of the n-Gd measurement. Based on a rate-only analysis, we obtain sin$^{2}$2$theta _{13}$= 0.087 $pm$ 0.008 (stat.) $pm$ 0.014 (syst.).
This presentation describes a measurement of the neutrino mixing parameter, sin^2(2theta_13), from the Daya Bay Reactor Neutrino Experiment. Disappearance of electron antineutrinos at a distance of ~2 km from a set of six reactors, where the reactor flux is constrained by near detectors, has been clearly observed. The result, based on the ratio of observed to expected rate of antineutrinos, using 139 days of data taken between December 24, 2011 and May 11, 2012, is sin^2(2theta_13) = 0.089 +/- 0.010(stat.) +/- 0.005(syst.). Improvements in sensitivity from inclusion of additional data, spectral analysis, and improved calibration are expected in the future.
The Double Chooz experiment has observed 8,249 candidate electron antineutrino events in 227.93 live days with 33.71 GW-ton-years (reactor power x detector mass x livetime) exposure using a 10.3 cubic meter fiducial volume detector located at 1050 m from the reactor cores of the Chooz nuclear power plant in France. The expectation in case of theta13 = 0 is 8,937 events. The deficit is interpreted as evidence of electron antineutrino disappearance. From a rate plus spectral shape analysis we find sin^2 2{theta}13 = 0.109 pm 0.030(stat) pm 0.025(syst). The data exclude the no-oscillation hypothesis at 99.8% CL (2.9{sigma}).
In [J. T. Matta et al., Phys. Rev. Lett. 114, 082501 (2015)] a transverse wobbling band was reported in $^{135}$Pr. The critical experimental proof for this assignment is the E2 dominated linking transitions between the wobbling and normal bands, which are supported by two experiments performed with Gammasphere and INGA. However, the M1 dominated character cannot be excluded based on the reported experimental information, indicating that the wobbling assignment is still questionable.
Thierry Lasserre
,Guillaume Mention
,Michel Cribier
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(2012)
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"Comment on Phys. Rev. Lett. 108, 191802 (2012): Observation of Reactor Electron Antineutrino Disappearance in the RENO Experiment"
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Thierry Lasserre
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