A search forν µ →ν e oscillations was conducted by the Liquid Scintillator Neutrino Detector at the Los Alamos Neutron Science Center usingν µ from µ + decay at rest. A total excess of 87.9 ± 22.4 ± 6.0 events consistent withν e p → e + n scattering was observed above the expected background. This excess corresponds to an oscillation probability of (0.264 ± 0.067 ± 0.045)%, which is consistent with an earlier analysis. In conjunction with other known limits on neutrino oscillations, the LSND data suggest that neutrino oscillations occur in the 0.2 − 10 eV 2 /c 4 ∆m 2 range, indicating a neutrino mass greater than 0.4 eV/c 2 .2
The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay -these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions.Experiments carried out over the past half century have revealed that neutrinos are found in three states, or flavors, and can transform from one flavor into another. These results indicate that each neutrino flavor state is a mixture of three different nonzero mass states, and to date offer the most compelling evidence for physics beyond the Standard Model. In a single experiment, LBNE will enable a broad exploration of the three-flavor model of neutrino physics with unprecedented detail. Chief among its potential discoveries is that of matter-antimatter asymmetries (through the mechanism of charge-parity violation) in neutrino flavor mixing -a step toward unraveling the mystery of matter generation in the early Universe. Independently, determination of the unknown neutrino mass ordering and precise measurement of neutrino mixing parameters by LBNE may reveal new fundamental symmetries of Nature.Grand Unified Theories, which attempt to describe the unification of the known forces, predict rates for proton decay that cover a range directly accessible with the next generation of large underground detectors such as LBNE's. The experiment's sensitivity to key proton decay channels will offer unique opportunities for the ground-breaking discovery of this phenomenon.Neutrinos emitted in the first few seconds of a core-collapse supernova carry with them the potential for great insight into the evolution of the Universe. LBNE's capability to collect and analyze this high-statistics neutrino signal from a supernova within our galaxy would provide a rare opportunity to peer inside a newly-formed neutron star and potentially witness the birth of a black hole.To achieve its goals, LBNE is conceived around three central components: (1) a new, highintensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a fine-grained near neutrino detector installed just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is ∼1,300 km from the neutrino source at Fermilab -a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions.With its exceptional combi...
The cross section for the elastic scattering reaction νe + e − → νe + e − was measured by the Liquid Scintillator Neutrino Detector using a µ + decay-at-rest νe beam at the Los Alamos Neutron Science Center. The standard model of electroweak physics predicts a large destructive interference between the charge current and neutral current channels for this reaction. The measured cross section, σ νee − = [10.1 ± 1.1(stat.) ± 1.0(syst.)] × Eν e (MeV) ×10 −45 cm 2 , agrees well with standard model expectations. The measured value of the interference parameter, I = −1.01 ± 0.13(stat.) ± 0.12(syst.), is in good agreement with the standard model expectation of I SM = −1.09. Limits are placed on neutrino flavorchanging neutral currents. An upper limit on the muon-neutrino magnetic moment of 6.8 × 10 −10 µ Bohr is obtained using the νµ andνµ fluxes from π + and µ + decay.
The largest sample ever recorded ofνµ charged-current quasielastic (CCQE,νµ + p → µ + + n) candidate events is used to produce the minimally model-dependent, flux-integrated doubledifferential cross section d 2 σ dTµd cos θµ forνµ CCQE for a mineral oil target. This measurement exploits the large statistics of the MiniBooNE antineutrino-mode sample and provides the most complete information of this process to date. In order to facilitate historical comparisons, the flux-unfolded total cross section σ (Eν) and single-differential cross section dσ dQ 2 on both mineral oil and on carbon are also reported. The observed cross section is somewhat higher than the predicted cross section from a model assuming independently-acting nucleons in carbon with canonical form factor values. The shape of the data are also discrepant with this model. These results have implications for intranuclear processes and can help constrain signal and background processes for future neutrino oscillation measurements.
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