MINOS for Scientists

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Recent Results

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ν_μ Disappearance - Energy Spectrum: This plot compares the 848 events in MINOS Far Detector (black points) to the expected neutrino energy distribution (1065 +- 60 events) in the absence of neutrino disappearance (red histogram). While most of the events are expected to be charged-current neutrino interactions, 5.9 neutral current (NC) background events are expected (shaded histogram barely visible in bottom corner), as well as 1.5 nu-tau interactions, 2.3 events from upstream neutrino interactions in the rock, and 0.7 cosmic ray events.
The data showing a clear deficit relative to the expected rate, we fit these data for the hypothesis of two-flavor oscillations, and the black histogram shows the expected spectrum corresponding to Δm²=(2.43±0.11)x10^-3 and sin²(2Θ)=1.00±0.05 which gives the best fit to the data, with a χ²/dof=90/97.

ν_μ Disappearance - Far/Near Spectrum Ratio: Ratio of the MINOS FD data energy spectrum to the energy spectrum expected in the absence of neutrino disappearance (black points). Also shown is the best fit to the oscillation hypothesis (black curve) and two fits of the MINOS data to alternative explanations for neutrino disappearance. Neutrino decay (V. Barger et al., Phys. Rev. Lett. 82 2640, 1999) is disfavored at the 3.7 standard deviation level (red curve), while quantum decoherence of neutrino wave packets (G. L. Fogli et al., Phys. Rev. D67 093006, 2003) is excluded at the 5.7 standard deviation level (blue curve).

ν_μ Disappearance - Oscillation Parameters Contour: Confidence Interval contours in the fit of the MINOS Far Detector data to the hypothesis of two-flavor oscillations. The black solid (dashed) curves give the 90% (68%) contours. The best fit point (constrained to lie within the physical region) is Δm²=(2.43±0.11)x10^-3 and sin²(2Θ)=1.00±0.05 which gives the best fit to the data, with a χ²/dof=90/97. Also shown are the previous MINOS result (PRL 97, 19801, 2006) in grey, and past results from the SuperKamiokande Collaboration (PRL 93, 101801, 2004; PRD 71, 112005, 2005), and the K2K collaboration (PRD 73, 112001, 2006)

ν_e Appearance: ν_e events appearing at the Far Detector can be used as a measure of the Θ₁₃ mixing angle. The plot shows the predicted MINOS sensitivity to the value of sin²(2Θ₁₃). Values to the right of the curves are the ranges of δ and sin²(2Θ₁₃) excluded at the 90% confidence level if MINOS observes a number of ν_e candidates equal to the predicted number of background events. The limit depends on the mass hierarchy. The limits in each hierarchy for the current exposure of 3.25e20 POT with 10% systematic error are shown in red and blue. The future limits that could be achieved with half the current systematic error and for two higher exposures of 6.5e20 POT (green) and 9.5e20 POT (purple) in the case of the normal hierarchy are also shown.

Sterile ν Search using Neutral Current Interactions - NC Spectrum: Because all active neutrino flavors participate in the neutral-current interaction while sterile neutrinos do not, MINOS can look for evidence of sterile neutrinos by comparing the rates of neutral-current interactions in the near and far detectors. This plot shows the reconstructed energy spectrum of neutral-current-like interactions in the near detector. The data are shown by the black points, the expectation from the Monte Carlo simulation and the systematic uncertainty in the expectation is shown by the red histogram, and the filled histogram shows the expected background from charged-current interactions of muon neutrinos.

Sterile ν Search using Neutral Current Interactions - Results: This plot shows the measured rate of neutral-current interactions in the MINOS far detector as a function of reconstructed energy along with the expected rates with and without electron neutrino appearance. The rates for the expectation were determined using the reconstructed energy spectrum from the near detector along with the Monte Carlo simulation of the far detector and the expectations account for the muon neutrino disappearance observed in the charged-current result. The predicted background from charged-current interactions of muon neutrinos at the far detector using the are also shown. The data are consistent with oscillations only occurring between the active neutrino flavors.

Text listing of MINOS publications
Listing of theses written by MINOS graduate students web page with links or text list
The Physics Motivation for the MINOS Experiment, from the MINOS Technical Design Report
Summary of the Experiment Design, from the MINOS Technical Design Report
Detector Design Parameter Book, in post-script and in PDF
The MINOS Complete Technical Design Report