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Register a new userMeasurement of Neutrino and Antineutrino Oscillations Using Beam and Atmospheric Data in MINOS
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We report measurements of oscillation parameters from $ u_{mu}$ and $bar{ u}_{mu}$ disappearance using beam and atmospheric data from MINOS. The data comprise exposures of unit[$10.71 times 10^{20}$]{protons on target (POT)} in the $ u_{mu}$-dominated beam, $unit[3.36times10^{20}]{POT}}$ in the $bar{ u}_{mu}$-enhanced beam, and 37.88 kton-years of atmospheric neutrinos. Assuming identical $ u$ and $bar{ u}$ oscillation parameters, we measure mbox{$|Delta m^2}| = unit[2.41^{+0.09}_{-0.10}) times 10^{-3}]{eV^{2}}$} and $sin^{2}/!/left(2theta right) = 0.950^{+0.035}_{-0.036}$. Allowing independent $ u$ and $bar{ u}$ oscillations, we measure antineutrino parameters of $|Delta bar{m}^2| = unit[(2.50 ^{+0.23}_{-0.25}) times 10^{-3}]{eV^{2}}$ and $sin^{2}/!/left(2bar{theta} right) = 0.97^{+0.03}_{-0.08}$, with minimal change to the neutrino parameters.
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This letter reports new results from the MINOS experiment based on a two-year exposure to muon neutrinos from the Fermilab NuMI beam. Our data are consistent with quantum mechanical oscillations of neutrino flavor with mass splitting $|Delta m^2|=(2.43pm 0.13)times10^{-3}$ eV$^2$ (68% confidence level) and mixing angle $sin^2(2theta)>0.90$ (90% confidence level). Our data disfavor two alternative explanations for the disappearance of neutrinos in flight, namely neutrino decays into lighter particles and quantum decoherence of neutrinos, at the 3.7 and 5.7 standard deviation levels, respectively.
The MINOS experiment ran from 2003 until 2012 and collected a data sample including 10.71x10^20 protons-on-target (POT) of beam neutrinos, 3.36x10^20 POT of beam antineutrinos and an atmospheric neutrino exposure of 37.88 kt-yrs. The final measurement of the atmospheric neutrino oscillation parameters, dm^2_32 and theta_23, came from a full three flavour oscillation analysis of the combined CC nu_mu and CC anti-nu_mu beam and atmospheric samples and the CC nu_e and CC anti-nu_e appearance samples. This analysis yielded the most precise measurement of the atmospheric mass splitting dm^2_32 performed to date. The results are |dm^2_32|=[2.28 - 2.46]x10^-3 eV^2 (68%) and sin^{2}theta_23=0.35-0.65$ (90%) in the normal hierarchy, and |dm^2_32|=[2.32 - 2.53]x10^-3 eV^2 (68%) and sin^{2}theta_23=0.34-0.67 (90%) in the inverted hierarchy. The successor to MINOS in the NOvA era at FNAL, MINOS+, is now collecting data mostly in the 3-10 GeV region, and an analysis of nu_mu disappearance using the first 2.99x10^20 POT of data produced results very consistent with those from MINOS. Future data will further test the standard neutrino oscillation paradigm and allow for improved searches for exotic phenomena including sterile neutrinos, large extra dimensions and non-standard interactions.
We report on $ u_e$ and $bar{ u}_e$ appearance in $ u_mu$ and $bar{ u}_mu$ beams using the full MINOS data sample. The comparison of these $ u_e$ and $bar{ u}_e$ appearance data at a 735 km baseline with $theta_{13}$ measurements by reactor experiments probes $delta$, the $theta_{23}$ octant degeneracy, and the mass hierarchy. This analysis is the first use of this technique and includes the first accelerator long-baseline search for $bar{ u}_murightarrowbar{ u}_e$. Our data disfavor 31% (5%) of the three-parameter space defined by $delta$, the octant of the $theta_{23}$, and the mass hierarchy at the 68% (90%) C.L. We measure a value of 2sin$^2(2theta_{13})$sin$^2(theta_{23})$ that is consistent with reactor experiments.
We report the final measurement of the neutrino oscillation parameters $Delta m^2_{32}$ and $sin^2theta_{23}$ using all data from the MINOS and MINOS+ experiments. These data were collected using a total exposure of $23.76 times 10^{20}$ protons on target producing $ u_{mu}$ and $overline{ u_mu}$ beams and 60.75 kt$cdot$yr exposure to atmospheric neutrinos. The measurement of the disappearance of $ u_{mu}$ and the appearance of $ u_e$ events between the Near and Far detectors yields $|Delta m^2_{32}|=2.40^{+0.08}_{-0.09}~(2.45^{+0.07}_{-0.08}) times 10^{-3}$ eV$^2$ and $sin^2theta_{23} = 0.43^{+0.20}_{-0.04} ~(0.42^{+0.07}_{-0.03})$ at 68% C.L. for Normal (Inverted) Hierarchy.
A high-density calorimeter, consisting of magnetized iron planes interleaved by RPCs, as tracking and timing devices, is a good candidate for a next generation experiment on atmospheric neutrinos. With 34 kt of mass and in four years of data taking, this experiment will be sensitive to $ u_mu to u_x$ oscillation with $Delta m^2 > 6 times 10^{-5}$ and mixing near to maximal and fully cover the region of oscillation parameters suggested by Super-Kamiokande results. Moreover, the experimental method will enable to measure the oscillation parameters from the modulation of the L/E spectrum ($ u_mu$ disappearance). For $Delta m^2 > 3 times 10^{-3}$ eV$^2$, this experiment can also establish whether the oscillation occurs into a tau or a sterile neutrino, by looking for an excess of muon-less events at high energies produced by upward-going tau neutrinos ($ u_tau$ appearance).
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