Measurement of the Multiple-Muon Charge Ratio in the MINOS Far Detector

TL;DR

This paper reports a precise measurement of the ratio of positive to negative muons in multiple-muon events at a deep underground detector, providing insights into cosmic ray interactions at TeV energies.

Contribution

The study presents the first high-precision measurement of the multiple-muon charge ratio at a deep underground site, reducing systematic uncertainties through dual magnetic field configurations.

Findings

Measured charge ratio R_mu = 1.104 ± 0.006 (stat.) +0.009/-0.010 (syst.)

Provides constraints on cosmic ray interaction models at TeV energies

Complements previous single-muon and multiple-muon charge ratio measurements.

Abstract

The charge ratio, $R_\mu = N_{\mu^+}/N_{\mu^-}$, for cosmogenic multiple-muon events observed at an under- ground depth of 2070 mwe has been measured using the magnetized MINOS Far Detector. The multiple-muon events, recorded nearly continuously from August 2003 until April 2012, comprise two independent data sets imaged with opposite magnetic field polarities, the comparison of which allows the systematic uncertainties of the measurement to be minimized. The multiple-muon charge ratio is determined to be $R_\mu = 1.104 \pm 0.006 {\rm \,(stat.)} ^{+0.009}_{-0.010} {\rm \,(syst.)} $. This measurement complements previous determinations of single-muon and multiple-muon charge ratios at underground sites and serves to constrain models of cosmic ray interactions at TeV energies.