1,721,053 research outputs found
Search for neutrino–antineutrino oscillations with a reactor experiment
No full textThe disappearance of reactor antineutrinos in the Double Chooz experiment is used to investigate the possibility of neutrino–antineutrino oscillations arising due to the breakdown of Lorentz invariance. We find no evidence for this phenomenon and set the first limits on 15 coefficients describing neutrino–antineutrino mixing within the framework of the Standard-Model Extension.National Science Foundation (U.S.) (PHY-1205175)MIT Department of Physics Pappalardo Program (Fellowship
Search for Lorentz Violation in km
Full text linkKilometer3-scale neutrino detectors such as IceCube, ANTARES, and the proposed Km3Net neutrino observatory in the Mediterranean have measured, and will continue to characterize, the atmospheric neutrino spectrum above 1 TeV. Such precise measurements enable us to probe new neutrino physics, in particular, those that arise from Lorentz violation. In this paper, we first relate the effective new physics hamiltonian terms with the Lorentz violating literature. Second, we calculate the oscillation probability formulas for the two-level vμ-vτ sector. Finally, we comment on some of the challenges and outlook for this analysis.National Science Foundation (U.S.) (Grant 1505858)National Science Foundation (U.S.) (Grant 1505855)Science and Technology Facilities Council (Great Britain
A measurement of the absorption of liquid argon scintillation light by dissolved nitrogen at the part-per-million level
Full text linkWe report on a measurement of the absorption length of scintillation light in liquid argon due to dissolved nitrogen at the part-per-million (ppm) level. We inject controlled quantities of nitrogen into a high purity volume of liquid argon and monitor the light yield from an alpha source. The source is placed at different distances from a cryogenic photomultiplier tube assembly. By comparing the light yield from each position we extract the absorption cross section of nitrogen. We find that nitrogen absorbs argon scintillation light with strength of (1.51±0.15) × 10[superscript −4] cm[superscript −1]ppm[superscript −1], corresponding to an absorption cross section of (4.99±0.51) × 10[superscript −21] cm[superscript 2]molecule[superscript −1]. We obtain the relationship between absorption length and nitrogen concentration over the 0 to 50 ppm range and discuss the implications for the design and data analysis of future large liquid argon time projection chamber (LArTPC) detectors. Our results indicate that for a current-generation LArTPC, where a concentration of 2 parts per million of nitrogen is expected, the attenuation length due to nitrogen will be 30±3 meters.National Science Foundation (U.S.) (NSF-PHY-1205175)United States. Dept. of Energy (DE-FG02-91ER40661
Search for core-collapse supernovae using the MiniBooNE neutrino detector
Full text linkWe present a search for core-collapse supernovae in the Milky Way galaxy, using the MiniBooNE neutrino detector. No evidence is found for core-collapse supernovae occurring in our Galaxy in the period from December 14, 2004 to July 31, 2008, corresponding to 98% live time for collection. We set a limit on the core-collapse supernova rate out to a distance of 13.4 kpc to be less than 0.69 supernovae per year at 90% C.L.Fermi National Accelerator LaboratoryUnited States. Dept. of EnergyNational Science Foundatio
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Observation of a Significant Excess of Electron-Like Events in the MiniBooNE Short-Baseline Neutrino Experiment
No full textThe MiniBooNE experiment at Fermilab reports results from an analysis of electron neutrino (nue) appearance data from 1.3E21 protons on target (POT) in neutrino mode, an increase of approximately a factor of two over previously reported results (PRL110(2013)161801). A nue charged-current quasi-elastic (CCQE) event excess of 381.2 +/- 85.2 events (4.5sigma) is observed in the energy range 200 < EnuQE < 1250 MeV.
Combining these data with the electron anti-neutrino (nuebar) appearance data from 1.1E21 POT in antineutrino mode, a total nue plus nuebar CCQE event excess of 460.5 +/- 95.8 events (4.8 sigma) is observed. If interpreted in a standard two-neutrino oscillation model (numu to nue), the best oscillation fit to the excess has a probability of 20.1% while the background-only fit has a chi2-probability of 5E-7 relative to the best fit. The MiniBooNE data are consistent in energy and magnitude with the excess of events reported by the Liquid Scintillator Neutrino Detector (LSND). All of the major backgrounds are constrained by in-situ event measurements, so non-oscillation explanations would need to invoke new anomalous background processes. https://arxiv.org/abs/1805.12028</p
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Charged-Current Interaction Measurements in MiniBooNE
Full text linkNeutrino oscillation is the only known phenomenon for physics beyond the standard model. To investigate this phenomenon, the understanding of low energy neutrino scattering (200<E<2000 MeV) is the crucial task for high energy physicists. In this energy region, the charged current quasi-elastic (CCQE) neutrino interaction is the dominant process, and experiments require a precise model to predict signal samples. Using a high-statistics sample of muon neutrino CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events on carbon. The extracted parameters include an effective axial mass, MA=1.23 {+-} 0.20 GeV, and a Pauli-blocking parameter, kappa = 1.019 {+-} 0.011
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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