Neutrino-Induced Muons Deep Underground

Abstract

We report here the results of a measurement of the integral energy distribution of the neutrino-induced muon flux deep underground using the Utah neutrino detector. Five neutrino-induced muon candidates have been obtained from the approximately ${10}^6$ muons which have passed through the detector during 603 days of live operation out of 830 days total elapsed time. By comparing the observed and expected energy distributions we are able to set lower limits on the saturation energy $E_0$ of the total neutrino-nucleon cross section or, equivalently, on the mass $M_W$ of the intermediate vector boson if scale invariance of the inelastic structure function $\nu W_2$ is assumed. We find at the $1\sigma$, $2\sigma$, and $3\sigma$ levels of confidence $E_0>320, 80, \mathrm{and} 29$ GeV or $M_W>10, 5, \mathrm{and} 3$ GeV, respectively.