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First observations of separated atmospheric nu(mu) and (nu)over-bar(mu) events in the MINOS detector

Adamson, P; Alexopoulos, T; Allison, WWM; Alner, GJ; Anderson, K; Andreopoulos, C; Andrews, M; ... MMINOS Collaboration; + view all (2006) First observations of separated atmospheric nu(mu) and (nu)over-bar(mu) events in the MINOS detector. PHYS REV D , 73 (7) , Article 072002. 10.1103/PhysRevD.73.072002. Green open access

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Abstract

The complete 5.4 kton MINOS far detector has been taking data since the beginning of August 2003 at a depth of 2070 meters water-equivalent in the Soudan mine, Minnesota. This paper presents the first MINOS observations of nu(mu) and (nu) over bar (mu) charged-current atmospheric neutrino interactions based on an exposure of 418 days. The ratio of upward- to downward-going events in the data is compared to the Monte Carlo expectation in the absence of neutrino oscillations, giving R-up/down(data)/R-up/down(MC)=0.62(-0.14)(+0.19)(stat.)+/- 0.02(sys.). An extended maximum likelihood analysis of the observed L/E distributions excludes the null hypothesis of no neutrino oscillations at the 98% confidence level. Using the curvature of the observed muons in the 1.3 T MINOS magnetic field nu(mu) and (nu) over bar (mu) interactions are separated. The ratio of (nu) over bar (mu) to nu(mu) events in the data is compared to the Monte Carlo expectation assuming neutrinos and antineutrinos oscillate in the same manner, giving R-(nu) over bar mu/nu(data)(mu)/R-(nu) over bar mu/nu(MC)(mu)=0.96(-0.27)(+0.38)(stat.)+/- 0.15(sys.), where the errors are the statistical and systematic uncertainties. Although the statistics are limited, this is the first direct observation of atmospheric neutrino interactions separately for nu(mu) and (nu) over bar (mu).

Type: Article
Title: First observations of separated atmospheric nu(mu) and (nu)over-bar(mu) events in the MINOS detector
Open access status: An open access version is available from UCL Discovery
DOI: 10.1103/PhysRevD.73.072002
Keywords: TOTAL CROSS-SECTION, GEV ENERGY-RANGE, NEUTRINO FLUX, SUPER-KAMIOKANDE, UNIFIED APPROACH, SYSTEM, MUONS, RATIO, SCATTERING, PROTONS
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/10087
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