Recent results from reactor antineutrino experiments

Hyunkwan Seo

doi:10.21468/scipostphysproc.1.027

Abstract

The smallest neutrino mixing angle \theta_{13}θ13 has been successfully measured by the disappearance of reactor antineutrinos at RENO, Daya Bay, and Double Chooz. The oscillation frequency is also measured based on energy and baseline dependent disappearance probability of reactor antineutrinos. Recent results find a variation in the observed reactor antineutrino flux as a function of the reactor fuel evolution. We report more precisely measured values of \theta_{13}θ13 and \Delta m_{ee}^2Δmee2 and results on the evolution of observed reactor antineutrino yield and spectrum.

Highlights

The reactor νe disappearance has been firmly observed to determine the smallest neutrino mixing angle θ13 [1,2,3]
Daya Bay collaboration reported an observation of reactor fuel dependent variation of the reactor νe flux and spectrum and concluded that the 235U fuel isotope may be the primary contributor to the Reactor Antineutrino Anomaly (RAA) [13]
No significant difference between the measured inverse beta decay (IBD) yield variation over effective fission fraction and HM prediction has been observed within experimental uncertainties for all the prompt energy ranges in both RENO and Daya Bay

Summary

Introduction

The reactor νe disappearance has been firmly observed to determine the smallest neutrino mixing angle θ13 [1,2,3]. Using the νe survival probability P [8], reactor experiments with a baseline distance of ∼1 km have determined the mixing angle θ13 and an effective squared mass difference ∆m2ee ≡ cos θ12∆m231 + sin θ12∆m232 [9], based on the rate, spectral and baseline information. Daya Bay collaboration reported an observation of reactor fuel dependent variation of the reactor νe flux and spectrum and concluded that the 235U fuel isotope may be the primary contributor to the RAA [13]. RENO collaboration reported the analysis result on the fuel dependent variation of the reactor νe flux and spectrum [14]. RENO collaboration showed a hint of correlation between the 5 MeV excess and the 235U fuel isotope fraction

Detection Method for Reactor Antineutrinos and Experimental Arrangements

Fuel-composition Dependent Reactor Antineutrino Yield and Spectrum

Findings

Conclusion