The final results of the search for the lepton flavour violating decay [equation]based on the full dataset collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013 and...

This final article about the CHOOZ experiment presents a complete description of the [equation]source and detector, the calibration methods and stability checks, the event reconstruction procedures...

The analysis of a combined data set, totaling $3.6\times {10}^{14}$ stopped muons on target, in the search for the lepton flavor violating decay ${\mu }^{+}\to e^{+}\gamma$ is presented. The data collected by the MEG experiment at the Paul Scherrer Institut show no excess of events compared to background expectations and yield a new upper limit on the branching ratio of this decay of $5.7\times {10}^{-13}$ (90% confidence level). This represents a four times more stringent limit than the previous world best limit set by MEG.

Initial results are presented from CHOOZ(1), a long-baseline reactor-neutrino vacuum-oscillation experiment. The data reported here were taken during the period March to October 1997, when the two reactors ran at combined power levels varying from zero to values approaching their full rated power of 8.5 GW (thermal). Electron antineutrinos from the reactors were detected by a liquid scintillation calorimeter located at a distance of about 1 km. The detector was constructed in a tunnel protected from cosmic rays by a 300 MWE rock overburden. This massive shielding strongly reduced potentially troublesome backgrounds due to cosmic-ray muons, leading to a background rate of about one event per day, more than an order of magnitude smaller than the observed neutrino signal. From the statistical agreement between detected and expected neutrino event rates, we find (at 90% confidence level) no evidence for neutrino oscillations in the <(nu)over bar>(e) disappearance mode for the parameter region given approximately by Delta m(2) > 0.9 10(-3) eV(2) for maximum mixing and sin(2)(2 theta) > 0.18 for large Delta m(2). (C) 1998 Elsevier Science B.V

We present a measurement of the flux of neutrino-induced upgoing muons (< E-nu > similar to 100 GeV) using the MACRO detector. The ratio of the number of observed to expected events integrated over all zenith angles is 0.74 +/- 0.036 (stat) +/- 0.046 (systematic) +/- 0.13 (theoretical). The observed zenith distribution for - 1.0 less than or equal to cos theta less than or equal to -0.1 does not fit well with the no oscillation expectation, giving a maximum probability for chi(2) Of 0.1%, The acceptance of the detector has been extensively studied using downgoing muons, independent analyses and Monte Carlo simulations. The other systematic uncertainties cannot be the source of the discrepancies between the data and expectations. We have investigated whether the observed number of events and the shape of the zenith distribution can be explained by a neutrino oscillation hypothesis. Fitting either the flux or zenith distribution independently yields mixing parameters of sin(2)2 theta = 1.0 and Delta m(2) of a few times 10(-3) eV(2). However, the observed zenith distribution does not fit well with any expectations, giving a maximum probability for chi(2) of 5% for the beat oscillation hypothesis, and the combined probability for the shape and number of events is 17%. We conclude that these data favor a neutrino oscillation hypothesis, but with unexplained structure in the zenith distribution not easily explained by either the statistics or systematics of the experiment. (C) 1998 Published by Elsevier Science B.V. All rights reserved

We present a new result based on an analysis of the data collected by the MEG detector at the Paul Scherrer Institut in 2009 and 2010, in search of the lepton-flavor-violating decay ${\mu }^{+}\to e^{+}\gamma$. The likelihood analysis of the combined data sample, which corresponds to a total of $1.8\times {10}^{14}$ muon decays, gives a 90% C.L. upper limit of $2.4\times {10}^{-12}$ on the branching ratio of the ${\mu }^{+}\to e^{+}\gamma$ decay, constituting the most stringent limit on the existence of this decay to date.