Estimate of the Energy of Upgoing Muons with Multiple Coulomb Scattering

Abstract

Upward throughgoing muons in underground detectors are induced by atmospheric ${\nu }_{\mu }$ with energies in the $1-10^{4}GeV$ range. The oscillations of atmospheric muon neutrinos should affect mainly those with energy smaller than $E_{\nu }\sim 50GeV$, or $E_{\mu }\le 10GeV$ . We analyzed the MACRO upward throughgoing muons data set, using the Multiple Coulomb Scattering to estimate the energy $E_{\mu }$ of muons crossing the detector. We analyzed the event distribution for six event subsamples with different values of $<{\ell }_{\nu }/E_{\nu }>$. The event distribution is in agreement with the hypothesis of neutrino oscillations with $\Delta m^2$ few times $10^{-3}e{V}^2$ and maximum mixing.

8 pages, 4 figures. Invited contribution to the NATO Advanced Research Workshop: Cosmic Radiation: From Astronomy To Particle Physics, 21-23 March 2001, Oujda (Morocco)