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Differential cross sections for the photoproduction of single charged pions from deuterium and hydrogen have been measured at pion center-of-mass angles between 30° and 90° and at photon energies between 3.0 and 3.7 GeV. The ratio of π− to π+ cross sections from deuterium is found to be appreciably smaller than 1.
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212 interactions of 2.75-Bev protons have been observed in a hydrogen-filled diffusion cloud chamber. The data indicate an elastic cross section of 15 millibarns, with about 9 millibarns cross section for single pion production, 13 millibarns for double, and 4 for triple. There is one example of quadruple pion production. One definite example of the production of heavy unstable particles was observed, and two doubtful cases. The median elastic scattering angle was 19° in the c.m. system. Angle and momentum distributions for inelastic events are consistent with those observed at lower energies.
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<jats:title>Abstract</jats:title> <jats:p> The existence of three distinct neutrino flavours, <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> , <jats:italic>ν</jats:italic> <jats:sub>μ</jats:sub> and <jats:italic>ν</jats:italic> <jats:sub>τ</jats:sub> , is a central tenet of the Standard Model of particle physics <jats:sup>1,2</jats:sup> . Quantum-mechanical interference can allow a neutrino of one initial flavour to be detected sometime later as a different flavour, a process called neutrino oscillation. Several anomalous observations inconsistent with this three-flavour picture have motivated the hypothesis that an additional neutrino state exists, which does not interact directly with matter, termed as ‘sterile’ neutrino, <jats:italic>ν</jats:italic> <jats:sub>s</jats:sub> (refs. <jats:sup>3–9</jats:sup> ). This includes anomalous observations from the Liquid Scintillator Neutrino Detector (LSND) <jats:sup>3</jats:sup> experiment and Mini-Booster Neutrino Experiment (MiniBooNE) <jats:sup>4,5</jats:sup> , consistent with <jats:italic>ν</jats:italic> <jats:sub>μ</jats:sub> → <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> transitions at a distance inconsistent with the three-neutrino picture. Here we use data obtained from the MicroBooNE liquid-argon time projection chamber <jats:sup>10</jats:sup> in two accelerator neutrino beams to exclude the single light sterile neutrino interpretation of the LSND and MiniBooNE anomalies at the 95% confidence level (CL). Moreover, we rule out a notable portion of the parameter space that could explain the gallium anomaly <jats:sup>6–8</jats:sup> . This is one of the first measurements to use two accelerator neutrino beams to break a degeneracy between <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> appearance and disappearance, which would otherwise weaken the sensitivity to the sterile neutrino hypothesis. We find no evidence for either <jats:italic>ν</jats:italic> <jats:sub>μ</jats:sub> → <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> flavour transitions or <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> disappearance that would indicate non-standard flavour oscillations. Our results indicate that previous anomalous observations consistent with <jats:italic>ν</jats:italic> <jats:sub>μ</jats:sub> → <jats:italic>ν</jats:italic> <jats:sub>e</jats:sub> transitions cannot be explained by introducing a single sterile neutrino state. </jats:p>
14 observation channels used in this analysis. The first 7 channels correspond to the BNB, while the last 7 channels correspond to the NuMI beam. Each set of seven channels is split by reconstructed event type as well as containment in the detector, fully contained (FC) or partially contained (PC). The seven channels in order are $\nu_e$CC FC, $\nu_e$CC PC, $\nu_\mu$CC FC, $\nu_\mu$CC PC, $\nu_\mu$CC $\pi^0$ FC, $\nu_\mu$CC $\pi^0$ PC, and NC $\pi^0$. Each channel contains 25 bins from 0 to 2500 MeV of reconstructed neutrino energy, with an additional overflow bin.
Four $\nu_e$CC observation channels, after constraints from 10 $\nu_\mu$CC and NC $\pi^0$ channels. The four channels in order are BNB $\nu_e$CC FC, BNB $\nu_e$CC PC, NuMI $\nu_e$CC FC, and NuMI $\nu_e$CC PC. Each channel contains 25 bins from 0 to 2500 MeV of reconstructed neutrino energy, with an additional overflow bin.
14 channel covariance matrix showing uncertainties and correlations between bins due to flux uncertainties, cross-section uncertainties, hadron reinteraction uncertainties, detector systematic uncertainties, Monte-Carlo statistical uncertainties, and dirt (outside cryostat) uncertainties. Data statistical uncertainties have not been included, but they can be calculated with the Combined Neyman-Pearson (CNP) method. Each channel contains 25 bins from 0 to 2500 MeV of reconstructed neutrino energy, with an additional overflow bin.
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