Optimization of a Very Low Energy Neutrino Factory for the Disappearance Into Sterile Neutrinos

TL;DR

This paper explores optimizing a Very Low Energy Neutrino Factory to detect sterile neutrino disappearance, emphasizing detector placement, systematic error reduction, and the impact of geometry and muon energy on sensitivity.

Contribution

It introduces a comprehensive analysis of detector configuration and systematic uncertainties for sterile neutrino searches at a VLENF, including geometry effects and optimal muon energies.

Findings

Near detector should be as close as possible to the source.

Far detector optimal distance is about 500-800 meters.

At least 10^19 muon decays are needed for effective exclusion of current parameter regions.

Abstract

We discuss short-baseline electron and muon neutrino disappearance searches into sterile neutrinos at a Very Low Energy Neutrino Factory (VLENF) with a muon energy between about two and four GeV. A lesson learned from reactor experiments, such as Double Chooz and Daya Bay, is to use near and far detectors with identical technologies to reduce the systematical errors. We therefore derive the physics results from a combined near-far detector fit and illustrate that uncertainties on cross sections x efficiencies can be eliminated in a self-consistent way. We also include the geometry of the setup, i.e., the extension of the decay straight and the muon decay kinematics relevant at the near detector, and we demonstrate that these affect the sensitivities for Delta m^2 > 30 eV^2, where oscillations take place already in the near detector. Compared to appearance searches, we find that the sensitivity depends on the locations of both detectors and the muon energy, where the near detector should be as close as possible to the source, and the far detector at about 500 to 800m. In order to exclude the currently preferred parameter region, at least 10^19 useful muon decays per polarity are needed for E_mu=2 GeV, or, alternatively, a higher muon energy can be used.