Physics with reactor neutrinos

Abstract

Neutrinos produced by nuclear reactors have played a major role in advancing our knowledge of the properties of neutrinos. The first direct detection of the neutrino, confirming its existence, was performed using reactor neutrinos. More recent experiments utilizing reactor neutrinos have also found clear evidence for neutrino oscillation, providing unique input for the determination of neutrino mass and mixing. Ongoing and future reactor neutrino experiments will explore other important issues, including the neutrino mass hierarchy and the search for sterile neutrinos and other new physics beyond the standard model. In this article, we review the recent progress in physics using reactor neutrinos and the opportunities they offer for future discoveries.

Current unknowns in the three-neutrino framework

“…Therefore, a proper combination should take into account a common set of nuisance parameters affecting the three experiments at the same time, within a unified analysis framework. A joint analysis might possibly clarify the apparent preference of Double Chooz for higher values of θ 13 [140] as compared with Daya Bay and RENO. Work is in progress towards this (technically difficult but scientifically worthwhile) joint analysis, as testified by dedicated meetings [143,144] and ongoing common activities mentioned, e.g., in [145,146,147].…”

“…Among reactor experiments, Daya Bay [135] dominates current bounds on (∆m 2 , θ 13 ), the corresponding uncertainties being a factor ∼ 2.5 smaller than in RENO [141,136] and significantly smaller than in Double Chooz [137] (see also [140]). Recent analyses have shown that the reactor data combination only leads to fractional differences (well below 1σ) in comparison with bounds from Daya Bay data alone [31,33].…”

“…At the time of [1], short-baseline reactor neutrino results [15] were compatible with null oscillations within statistical and systematic errors. The development of the near-far detection technique [134] and the construction of massive detectors allowed to reduce the uncertainties and to discover θ 13 , currently measured by three experiments: Daya Bay [22,103,135], RENO [23,101,136] and Double Chooz [21,102,137]; see [138,139,140] for recent reviews. Detailed spectral information actually allows to determine joint bounds on (∆m 2 , θ 13 ), as demonstrated by RENO [141] and Daya Bay [135], the latter setting bounds on ∆m 2 competitive with those from LBL accelerator data [140].…”

White Paper on New Opportunities at the Next-Generation Neutrino Experiments (Part 1: BSM Neutrino Physics and Dark Matter)

“…There is an ongoing world-wide program of very short baseline (∼10 m) reactor neutrino experiments in search of sterile neutrino oscillations [121,129]. Almost all of these experiments use liquid or solid scintillator detectors at shallow depth constrained by the locations of the reactor complex.…”

“…In addition, several other experiments have proposed measuring long-lived particles including neutrinos at the LHC such as FASER [119], which was recently approved and funded, and MATHUSLA [120]. Figure 6: Theν e flux produced f rom the fission chain of the most common nuclear reactor isotopes [121]. The inverse beta decay threshold is indicated by the magenta vertical line.…”