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

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 $10^{-3}$).