Measurement of the Neutrino-induced Semi-contained Events in MACRO

TL;DR

This paper reports on the measurement of low-energy neutrino interactions in the MACRO detector, revealing a significant deficit consistent with neutrino oscillations, supporting the oscillation hypothesis at these energies.

Contribution

First analysis of low-energy neutrino interactions in MACRO showing evidence of neutrino oscillations with parameters aligned with previous high-energy observations.

Findings

Observed a large deficit in neutrino interactions compared to no-oscillation predictions.

Results support neutrino oscillations with maximal mixing and Δm² of a few times 10⁻³ eV².

Findings are consistent with other MACRO and experimental results.

Abstract

A preliminary analysis is presented of low-energy ($\bar{E_\nu} \sim 4 GeV$) neutrino interactions observed by the MACRO detector. These include neutrino interactions in the detector, as well as upgoing neutrino-induced muons that stop in the detector. At these energies, essentially all observed interactions can be attributed to atmospheric neutrinos. A large deficit is observed compared to a no-oscillations Monte Carlo prediction, although the systematic errors are large. However, the observation agrees well with neutrino oscillations with parameters suggested by the MACRO upward throughgoing muon analysis as well as other experiments (maximal mixing with $\Delta m^2$ of a few times $10^{-3}$).