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Measurements of atmospheric neutrinos and antineutrinos in the MINOS Far Detector

Research output: Contribution to journalJournal article

Published

Article number052007
Journal publication date17/09/2012
JournalPhysical Review D – Particles and Fields
Journal number5
Volume86
Number of pages20
Original languageEnglish

Abstract

This paper reports measurements of atmospheric neutrino and antineutrino interactions in the MINOS Far Detector, based on 2553 live-days (37.9 kton-years) of data. A total of 2072 candidate events are observed. These are separated into 905 contained-vertex muons and 466 neutrino-induced rock-muons, both produced by charged-current νμ and ν̅ μ interactions, and 701 contained-vertex showers, composed mainly of charged-current νe and ν̅ e interactions and neutral-current interactions. The curvature of muon tracks in the magnetic field of the MINOS Far Detector is used to select separate samples of νμ and ν̅ μ events. The observed ratio of ν̅ μ to νμ events is compared with the Monte Carlo (MC) simulation, giving a double ratio of Rν̅ /νdata/Rν̅ /νMC=1.03±0.08(stat)±0.08(syst). The νμ and ν̅ μ data are separated into bins of L/E resolution, based on the reconstructed energy and direction of each event, and a maximum likelihood fit to the observed L/E distributions is used to determine the atmospheric neutrino oscillation parameters. This fit returns 90% confidence limits of |Δm2|=(1.9±0.4)×10-3  eV2 and sin⁡22θ>0.86. The fit is extended to incorporate separate νμ and ν̅ μ oscillation parameters, returning 90% confidence limits of |Δm2|-|Δm̅ 2|=0.6-0.8+2.4×10-3  eV2 on the difference between the squared-mass splittings for neutrinos and antineutrinos.

Bibliographic note

© 2012 American Physical Society