Published: 2010
Total Pages: 157
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Abstract The Main Injector Neutrino Oscillation Search (MINOS) obse rves the disappearance of muon neutrinos as they propagate in the long baseline Neutri nos at the Main Injector (NuMI) beam. MINOS consists of two detectors. The near detector sam ples the initial composition of the beam. The far detector, 735 km away, looks for an energy-d ependent deficit in the neutrino spectrum. This energy-dependent deficit is interpreted as q uantum mechanical oscillations be- tween neutrino flavors. A measurement is made of the effective two-neutrino mixing parameters ? m 2 ≈ ? m 2 23 and sin 2 2 ? ≈ sin 2 2 ? 23 . The primary MINOS analysis uses charged current events in the fiducial volume of the far detector. This analysis uses the roughly equal-sized sample of events that fails the fiducial cut, consisting of interact ions outside the fiducial region of the detector and in the surrounding rock. These events provide a n independent and complementary measurement, albeit weaker due to incomplete reconstructi on of the events. This analysis reports on an exposure of 7 . 25 × 10 20 protons-on-target. Due to poor energy resolution, the meas urement of sin 2 2 ? is much weaker than established results, but the measuremen t of sin 2 2 ? > 0 . 56 at 90% confidence is consistent with the accepted value. The measur ement of ? m 2 is much stronger. Assuming sin 2 2 ? = 1 , ? m 2 = (2 . 20 ± 0 . 18[stat] ± 0 . 14[syst]) × 10 - -3 eV 2 .