- FIRST MINOS+ RESULTS - FAR DETECTOR CHARGED CURRENT SPECTRUM (June 2014)
- The MINOS+ experiment has operated since September 2013 using the upgraded NuMI accelerator neutrino beam, which is now running in a medium-energy configuration. This figure shows the first spectrum of ν_{μ} and ν_{μ} charged-current interactions in the MINOS+ Far Detector, summed with the existing low-energy data from MINOS. The hatched histograms show the predicted spectra for MINOS and MINOS+, calculated using the best-fit oscillation parameters from MINOS. The two predictions are summed to give a combined spectrum, which is shown by the blue histogram along with its 1σ systematic uncertainty band. In addition, the red histogram shows the combined spectrum for the case of no oscillations. The observed data, indicated by the points with errors, are well-described by the oscillation model. The MINOS+ data significantly increase the event yield in the medium-energy region, enabling precision measurements of the ν_{μ} survival probability curve.
Published Results
- a listing of all journal publications by the MINOS collaboration
- a listing of theses written by MINOS graduate students, available as a web page with links or a text list
The Public Materials Page provides downloadable PDF files of plots and diagrams from recent results, formatted as presentation slides. These files are released by MINOS for public use by non-MINOS scientists. All have been presented at recent conferences and represent published or soon-to-be published results.
Highlights from Recent Results
Plots and brief explanatory text for recent MINOS results. All plots shown here are available as downloadable PDFs on the Public Materials page. Click on the plot image for a full-page version.
- FIRST MINOS+ RESULTS - ν_{μ} SURVIVAL PROBABILITY CURVE (June 2014)
- This figure shows the ratio of the observed spectrum of accelerator ν_{μ} CC and ν_{μ} CC interations from MINOS and MINOS+, calculated with respect to the predicted spectrum without oscillations. The blue curve shows the corresponding oscillated prediction and its 1σ systematic uncertainty band, calculated using the best-fit oscillation parameters from MINOS. The observed data are well-described by the oscillation model.
- UPDATED OSCILLATION RESULTS - COMBINED ANALYSIS OF ν_{μ} DISAPPEARANCE AND ν_{e} APPEARANCE (June 2014)
- This figure shows the latest oscillation results from MINOS, which have been updated for the Neutrino 2014 conference. The results are based on a combined analysis of ν_{μ} disappearance and ν_{e} appearance, and use both the accelerator and atmospheric data from MINOS. The atmospheric data set has been increased by 30% with respect to the previous results from MINOS. The red contours in this figure show the 2D confidence limits on the parameters Δm^{2}_{32} and sin^{2}θ_{23} obtained for the normal (top panel) and inverted (bottom panel) hierarchy. The single-parameter 68% confidence intervals are: Δm^{2}_{32}= (2.34^{+0.09}_{-0.09} )x10^{-3} eV^{2} and sin^{2}θ_{23}= 0.43^{+0.16}_{-0.04} for the normal hierarchy; and Δm^{2}_{32}= -(2.37^{+0.11}_{-0.07} )x10^{-3} eV^{2} and sin^{2}θ_{23}= 0.43^{+0.19}_{-0.05} for the inverted hierarchy. For comparison, the blue contours show the published ν_{μ} disappearance results from T2K (PRL 112, 181801, 2014). The 2D contours from MINOS are available here as a ROOT file.
- STERILE ANALYSIS - COMBINATION WITH BUGEY (June 2014)
- Unitarity constraints generate relationships between ν_{μ}↔ν_{e} transitions and ν_{e} and ν_{μ} disappearance. In this figure, the ν_{μ} disappearance results from MINOS are combined with ν_{e} disappearance results from the Bugey reactor experiment to yield 90% C.L. limits on the sterile mixing parameter sin^{2}2θ_{μe} = 4|U_{e4}|^{2}|U_{μ4}|^{2}, relevant to ν_{μ}↔ν_{e} transition experiments also shown. Regions of parameter space to the right of the red contour are excluded at 90% C.L. The MINOS data correspond to a 10.56x10^{20} POT exposure in neutrino running mode. The Bugey results are obtained from a GLoBES 2012 fit provided by P. Huber. It accounts for the new calculation of reactor fluxes, as described in P. Huber, Phys. Rev. C 85 029901 (2011). The MiniBooNE contours are provided by the MiniBooNE Collaboration and were published in A. A. Aguilar-Arevalo et al., Phys. Rev. Lett. 110, 161801 (2013).
- STERILE ANALYSIS - 90% C.L. CONTOUR (February 2015)
- MINOS searches for light sterile neutrinos that mix with the active neutrino flavors using charged-current and neutral-current neutrino interactions. No evidence for sterile neutrinos is found in the MINOS data. This figure shows the 90% C.L. excluded regions on the parameter space Δm^{2}_{43} vs. sin^{2}(2θ_{24}) obtained from the MINOS analysis compared to CDHS, CCFR, SciBooNE and MiniBooNE experiments. MINOS takes advantage of its long baseline and broad energy spectrum to probe previously unexplored regions of this parameter space.
- STERILE ANALYSIS - SPECTRUM OF CHARGED CURRENT EVENTS (February 2015)
- This figure shows the far detector prediction of charged-current reconstructed neutrino energy spectrum including backgrounds and the total systematic uncertainty and compares it to the observed MINOS data. The prediction assumes a three-flavor oscillation scenario with parameters Δm^{2}_{21}=7.59x10^{-5} eV^{2}, Δm^{2}_{32}=2.41x10^{-3} eV^{2}, sin^{2}θ_{13}=0.024, sin^{2}θ_{12}=0.319, and sin^{2}θ_{23}=0.388. No evidence of deviations from the standard three-flavor oscillation picture is found. MINOS uses these results to set limits on the existence of light sterile neutrinos.
- STERILE ANALYSIS - SPECTRUM OF NEUTRAL CURRENT EVENTS (February 2015)
- This figure shows the far detector prediction of neutral-current reconstructed neutrino energy spectrum including backgrounds and the total systematic uncertainty and compares it to the observed MINOS data. The prediction assumes a three-flavor oscillation scenario with parameters Δm^{2}_{21}=7.59x10^{-5} eV^{2}, Δm^{2}_{32}=2.41x10^{-3} eV^{2}, sin^{2}θ_{13}=0.024, sin^{2}θ_{12}=0.319, and sin^{2}θ_{23}=0.388. No evidence of deviations from the standard three-flavor oscillation picture is found. MINOS uses these results to set limits on the existence of light sterile neutrinos.
- NONSTANDARD INTERACTION (NSI) LIMITS - ν_{e} APPEARANCE (June 2014)
- The appearance of ν_{e} events at the Far Detector is sensitive to the NSI parameters ε_{eτ} and δ_{eτ}. These plots show the 90% C.L. allowed values of ε_{eτ} and δ_{eτ}+δ_{CP} assuming a normal hierarchy (top plot) and an inverted hierarchy (bottom plot). The appearance rate also depends on standard oscillation parameters which are assumed to be the following: sin^{2}θ_{23}=0.5, sin^{2}θ_{13}=0.025, and Δ m^{2}_{32}=2.43×10^{-3} eV^{2}. The contour is produced by marginalizing over the values of δ_{CP}.
Previous Results reported in 2013
- COMBINED ANALYSIS OF ν_{μ} DISAPPEARANCE AND ν_{e} APPEARANCE USING BEAM AND ATMOSPHERIC DATA (August 2013)
- MINOS has performed a combined analysis of ν_{μ} disappearance and ν_{e} appearance using its complete set of accelerator and atmospheric neutrino data. The analysis uses a full three-flavour framework, with the oscillation parameters Δm^{2}_{32}, θ_{23}, θ_{13} and δ_{CP} varied in the fit. The analysis also incorporates an external constraint of sin^{2}θ_{13}=0.0242±0.0025, based on an average of reactor neutrino measurements. The left panels of this figure show the 2D confidence levels on Δm^{2}_{32} and θ_{23} for the normal and inverted hierarchy. The contours are calculated relative to the overall best fit point of Δm^{2}_{32}=-2.41x10^{-3} eV^{2} and sin^{2}θ_{23}=0.41, which is indicated by the star. The right panels show the corresponding 1D log-likelihood profiles as a function of Δm^{2}_{32} and θ_{23}. The single-parameter confidence limits are: Δm^{2}_{32}=[2.28-2.46]x10^{-3} eV^{2} (68% C.L.) and sin^{2}θ_{23}=[0.35-0.65] (90% C.L.) for the normal hierarchy; and Δm^{2}_{32}=[2.32-2.53]x10^{-3} eV^{2} (68% C.L.) and sin^{2}θ_{23}=[0.34-0.67] (90% C.L.) for the inverted hierarchy. The 2D contours are available here as a ROOT file. More details on the analysis can be found in arXiv:hep-ex/1403.0867 - published in Phys. Rev. Lett. 112, 191801 (2014).
- COMBINED ANALYSIS OF ν_{μ} DISAPPEARANCE AND ν_{e} APPEARANCE USING BEAM AND ATMOSPHERIC DATA (August 2013)
- This figure shows the 1D likelihood profile for the δ_{CP} parameter resulting from the combined analysis of ν_{μ} disappearance and ν_{e} appearance by MINOS using its complete set of accelerator and atmospheric neutrino data. Separate profiles are plotted for each combination of mass hierarchy and θ_{23} octant. The best fit occurs in the inverted hierarchy and lower octant; the worst fit is the normal hierarchy and upper octant, which is disfavoured by -2ΔlogL=1.74. The dashed horizontal lines indicate the 68\% (90\%) single-parameter confidence limits, which disfavour 36\% (11\%) of the three-parameter space defined by the mass hierarchy, θ_{23} octant, and δ_{CP}. More details on the analysis can be found in arXiv:hep-ex/1403.0867 - published in Phys. Rev. Lett. 112, 191801 (2014).
- COMBINED ANALYSIS - OBSERVED SPECTRA OF BEAM AND ATMOSPHERIC NEUTRINOS (August 2013)
- This figure shows the observed distributions of muon neutrino and muon antineutrino charged-current interactions in the MINOS Far Detector. The top row shows the energy spectra for MINOS accelerator data, separated by event type and beam configuration. The bottom rows shows the zenith angle distributions of MINOS atmospheric data, separated by energy and event type. These spectra form the ν_{μ} CC and ν_{μ} CC inputs to the combined analysis of ν_{μ} disappearance and ν_{e} appearance described in Phys. Rev. Lett. 112, 191801 (2014). In each case, the gray histograms show the predictions without oscillations; the red histograms show the best-fit oscillations; and the black points show the observed data.
- ν_{μ} DISAPPEARANCE - OSCILLATION MEASUREMENT USING BEAM AND ATMOSPHERIC DATA (May 2013)
- This figure shows the 90% confidence level contours for the neutrino oscillation parameters obtained by MINOS and other experiments. The MINOS analysis uses all ν_{μ} and ν_{μ} charged current interactions, assuming identical oscillation parameters for neutrinos and antineutrinos. The black line shows the 90% CL contour obtained from a combined analysis of the MINOS beam and atmospheric neutrino data. The red line shows the analysis of MINOS beam data only. These results are compared to the the measurements from Super-Kamiokande (blue) and T2K (green). The best fit point for the MINOS combined analysis is Δm^{2}=(2.41^{+0.09}_{-0.10} )x10^{-3} eV^{2}, sin^{2}(2Θ)=0.950^{+0.035}_{-0.036}, or sin^{2}(2Θ) > 0.890 (90% CL). A tabular form of the likelihood surface from this analysis can be found here as a csv file, which lists sin^{2}(2Θ), Δm^{2} and Δln(L) in three columns. The likelihood surface is also available here as a ROOT file. More details on this analysis can be found in arXiv:hep-ex/1304.6335 - published in Phys. Rev. Lett. 110, 2518011 (2013).
- ν_{μ} DISAPPEARANCE - ANTINEUTRINO OSCILLATION MEASUREMENT USING BEAM AND ATMOSPHERIC DATA (May 2013)
- This figure shows the 90% confidence level contours for the antineutrino oscillation parameters. The black line shows the 90% CL contour obtained from the combined analysis of all the MINOS beam and atmospheric neutrino data, allowing the neutrino and antineutrino oscillation parameters to float independently. Also shown are the MINOS antineutrino measurements using beam data only (red) and atmospheric data only (blue), as well as the Super-Kamiokande antineutrino measurement (dashed). The best fit antineutrino oscillation parameters obtained by the MINOS combined analysis are Δm^{2}=(2.50^{+0.23}_{-0.25} )x10^{-3} eV^{2}, sin^{2}(2Θ)=0.97^{+0.03}_{-0.08}, or sin^{2}(2Θ) > 0.83 (90% CL). More details on this analysis can be found in arXiv:hep-ex/1304.6335 - published in Phys. Rev. Lett. 110, 2518011 (2013).
- ν_{μ} DISAPPEARANCE - OBSERVED SPECTRA OF BEAM AND ATMOSPHERIC NEUTRINOS (May 2013)
- This figure shows the observed distributions of muon neutrino and muon antineutrino charged-current interactions in the MINOS Far Detector. The top row of graphs shows the energy spectra for MINOS beam data, the bottom row shows the L/E distributions for MINOS atmospheric data. In each case, the black line shows the prediction without oscillations; the red line shows the best fit to oscillations; and the black points show the observed data. This plot is available here as a ROOT file
- ν_{e} APPEARANCE ANALYSIS - LIMITS and BOUNDS
- ν_{e} events appearing at the Far Detector can be used as a measure of the θ_{13} mixing angle. The plots show the allowed ranges and best fits for 2sin^{2}(2θ_{13})sin^{2}(θ_{23}) as a function of the CP-violating phase δ. The upper (lower) panel assumes the normal (inverted) neutrino mass hierarchy. (The value of δ and the mass hierarchy are fixed in the fit). This fit combines data taken in the neutrino-enhanced and antineutrino-enhanced beam modes. The contour is available here as a ROOT file along with a description of the contents.