Regular Article – Experimental Physics
Potential impact of sub-structure on the determination of neutrino mass hierarchy at medium-baseline reactor neutrino oscillation experiments
School of Physics, Harbin Institute of Technology, Harbin, China
2 School of Physics, Sun Yat-Sen University, Guangzhou, China
3 Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai, China
Accepted: 13 November 2020
Published online: 3 December 2020
In the past decade, the precise measurement of the lastly known neutrino mixing angle has enabled the resolution of neutrino mass hierarch (MH) at medium-baseline reactor neutrino oscillation (MBRO) experiments. Recent calculations of the reactor neutrino flux predict percent-level sub-structures in the spectrum due to Coulomb effects in beta decay. Such fine structure in the reactor spectrum has been an issue of concern for efforts to determine the neutrino MH for the MBRO approach, the concern being that the sub-dominant oscillation pattern used to discriminate different hierarchies will be obscured by fine structure. The energy resolutions of current reactor experiments are not sufficient to measure such fine structure, and therefore the size and location in energy of these predicted discontinuities has not been confirmed experimentally. There has been speculation that a near detector is required with sufficient energy resolution to resolve the fine structure. This article studies the impact of fine structure on the resolution of MH, based on predicted reactor neutrino spectra, using the measured spectrum from Daya Bay as a reference. We also investigate how a near detector could improve the sensitivity of neutrino MH resolution based on various assumptions of near detector energy resolution.
© The Author(s) 2020. corrected publication 2020
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