Search for sterile neutrino oscillations using RENO and NEOS data

Abstract

We present a nearly reactor model independent search for sterile neutrino oscillation using 2 509 days of RENO near detector data and 180 days of NEOS data. The reactor related systematic uncertainties are significantly suppressed as both detectors are located at the same reactor complex of Hanbit Nuclear Power Plant. The search is performed by electron antineutrino ((nu) over bar (e)) disappearance between six reactors and two detectors with flux-weighted baselines of 419 m (RENO) and 24 m (NEOS). A spectral comparison of the NEOS prompt-energy spectrum with a no-oscillation prediction from the RENO measurement can explore reactor (nu) over bar (e) oscillations to sterile neutrino. Based on the comparison, we obtain a 95% C.L. excluded region of 0.1 < vertical bar Delta m(4)(1)(2)vertical bar < 7 eV(2). We also obtain a 68% C.L. allowed region with the best fit of vertical bar Delta m(4)(1)(2)vertical bar = 2.41 eV(2) and sine(2) 2 theta(14) = 0.08 having a p-value of 8.2%. Comparisons of obtained reactor antineutrino spectra at reactor sources are made among RENO, NEOS, and Daya Bay to find a possible spectral variation.