Abstract
The MINOS experiment, operating in the NuMI beam since 2005, has provided the most precise measurement of the atmospheric mass splitting |Δm232|, and the recent combination of the vμ, ve, and atmospheric neutrino samples has provided some evidence of non-maximal mixing, and hints about the neutrino mass hierarchy and the θ23 octant. Construction of the NOvA experiment, situated off-axis in the upgraded NuMI beam, is almost complete. Over the coming years it will have significant power to probe the questions of the mass hierarchy, θ23 octant, and the possibility of CP violation in the lepton sector. This paper gives an overview of the results from MINOS, and of the sensitivity of the NOνA experiment.
Highlights
The MINOS and NOνA experiments are both situated on the NuMI neutrino beam-line. 120GeV protons from the Fermilab Main Injector strike a graphite target, the resulting pions are focussed by two magnetic horns, and decay to produce a beam of primarily muon neutrinos
MINOS The MINOS detectors are magnetized steel-scintillator tracking sampling calorimeters. They consist of alternating planes of 2.54cm thick steel and 4.1cm×1cm solid scintillator strips
Combining the information provided by the νμ, atmospheric, and νe samples, plus additional constraints on θ13 from reactor experiments provides some sensitivity to the neutrino hierarchy and θ23 octant
Summary
The MINOS and NOνA experiments are both situated on the NuMI neutrino beam-line. 120GeV protons from the Fermilab Main Injector strike a graphite target, the resulting pions are focussed by two magnetic horns, and decay to produce a beam of primarily muon neutrinos. Extrapolating from the observed neutrino spectrum in the Near Detector, in the absence of oscillations, MINOS would expect to select 3201 νμ interactions in the Far Detector, and 363 interactions in the antineutrino running. The inclusion of atmospheric neutrino samples into the analysis provides additional sensitivity, to the mass hierarchy.
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