Charge-Separated Atmospheric Neutrino-Induced Muons in the MINOS Far Detector

TL;DR

This paper reports the detection of 140 neutrino-induced muons in the MINOS detector over 854 days, providing evidence for neutrino oscillations and testing CPT symmetry through muon charge ratios.

Contribution

First measurement of atmospheric neutrino-induced muons in MINOS with analysis of oscillation parameters and CPT symmetry testing.

Findings

Data ratio consistent with neutrino oscillations

Null oscillation hypothesis excluded at 94% confidence

Muon charge ratio consistent with CPT conservation

Abstract

We found 140 neutrino-induced muons in 854.24 live days in the MINOS far detector. We looked for evidence of neutrino disappearance in this data set by computing the ratio of the number of low momentum muons to the sum of the number of high momentum and unknown momentum muons for both data and Monte Carlo expectation in the absence of neutrino oscillations. The ratio of data and Monte Carlo ratios is consistent with an oscillation signal. A fit to the data for the oscillation parameters excludes the null oscillation hypothesis at the 94% confidence level. We separated the muons by charge sign in both the data and Monte Carlo events and found the ratio of the total number of negative to positive muons in both samples. The ratio of those ratios is a test of CPT conservation. The result is consistent with CPT conservation.