A Decisive Disappearance Search at High-$\Delta m^2$ with Monoenergetic Muon Neutrinos

TL;DR

KPipe is a proposed experiment at J-PARC to search for muon neutrino disappearance caused by sterile neutrinos, utilizing monoenergetic neutrinos and a long detector to improve sensitivity over current limits.

Contribution

It introduces a novel, cost-effective detector design for high-$elta m^2$ sterile neutrino searches with minimal systematic uncertainties.

Findings

Extends sensitivity to high-$elta m^2$ oscillations by an order of magnitude.

Uses a shape-only $L/E$ analysis to reduce systematic errors.

Employs a monoenergetic neutrino source for robust measurements.

Abstract

"KPipe" is a proposed experiment which will study muon neutrino disappearance for a sensitive test of the $\Delta m^2\sim1 \mathrm{eV}^2$ anomalies, possibly indicative of one or more sterile neutrinos. The experiment is to be located at the J-PARC Materials and Life Science Facility's spallation neutron source, which represents the world's most intense source of charged kaon decay-at-rest monoenergetic (236 MeV) muon neutrinos. The detector vessel, designed to measure the charged current interactions of these neutrinos, will be 3 m in diameter and 120 m long, extending radially at a distance of 32 m to 152 m from the source. This design allows a sensitive search for $\nu_\mu$ disappearance associated with currently favored light sterile neutrino models and features the ability to reconstruct the neutrino oscillation wave within a single, extended detector. The required detector design, technology, and costs are modest. The KPipe measurements will be robust since they depend on a known energy neutrino source with low expected backgrounds. Further, since the measurements rely only on the measured rate of detected events as a function of distance, with no required knowledge of the initial flux and neutrino interaction cross section, the results will be largely free of systematic errors. The experimental sensitivity to oscillations, based on a shape-only analysis of the $L/E$ distribution, will extend an order of magnitude beyond present experimental limits in the relevant high-$\Delta m^2$ parameter space.