Measuring the mass of a sterile neutrino with a very short baseline reactor experiment

TL;DR

This paper proposes using harmonic oscillations in electron neutrino survival probability at very short baselines to measure sterile neutrino mass-squared differences, enhancing detection sensitivity.

Contribution

It introduces a novel method leveraging harmonic oscillations in L/E to determine sterile neutrino parameters in short-baseline reactor experiments.

Findings

Identified peaks at Δm² ≈ 0.9 eV² and 1.9 eV² in oscillation data.

Demonstrated the method's independence from reactor size at lowest order.

Suggested small reactors with very short baselines for improved measurements.

Abstract

An analysis of the world's neutrino oscillation data, including sterile neutrinos, (M. Sorel, C. M. Conrad, and M. H. Shaevitz, Phys. Rev. D 70, 073004) found a peak in the allowed region at a mass-squared difference $\Delta m^2 \cong 0.9$ eV$^2$. We trace its origin to harmonic oscillations in the electron survival probability $P_{ee}$ as a function of L/E, the ratio of baseline to neutrino energy, as measured in the near detector of the Bugey experiment. We find a second occurrence for $\Delta m^2 \cong 1.9$ eV$^2$. We point out that the phenomenon of harmonic oscillations of $P_{ee}$ as a function of L/E, as seen in the Bugey experiment, can be used to measure the mass-squared difference associated with a sterile neutrino in the range from a fraction of an eV$^2$ to several eV$^2$ (compatible with that indicated by the LSND experiment), as well as measure the amount of electron-sterile neutrino mixing. We observe that the experiment is independent, to lowest order, of the size of the reactor and suggest the possibility of a small reactor with a detector sitting at a very short baseline.