8 research outputs found

    Measurements of atmospheric muon neutrino oscillations, global analysis of the data collected with MACRO detector

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    The final analysis of atmospheric neutrino events collected with the MACRO detector is presented. Three different classes of events, generated by neutrinos in different energy ranges, are studied looking at rates, angular distributions and estimated energies. The results are consistent for all the subsamples and indicate a flux deficit that depends on energy and path - length of neutrinos. The no - oscillation hypothesis is excluded at similar to 5sigma, while the hypothesis of nu(mu) --> nu(tau) oscillation gives a satisfactory description of all data. The parameters with highest probability in a two flavor scenario are sin(2) 2theta(m) = 1 and Deltam(2) = 0.0023 eV(2). This result is independent of the absolute normalization of the atmospheric neutrino fluxes. The data can also be used to put experimental constrain on this normalization

    Measurements of atmospheric muon neutrino oscillations,global analysis of the data collected with MACRO detector

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    The final analysis of atmospheric neutrino events collected with the MACRO detector is presented. Three different classes of events, generated by neutrinos in different energy ranges, are studied looking at rates, angular distributions and estimated energies. The results are consistent for all the subsamples and indicate a flux deficit that depends on energy and path-length of neutrinos. The no-oscillation hypothesis is excluded at ∼ 5σ, while the hypothesis of νμ → ντ oscillation gives a satisfactory description of all data. The parameters with highest probability in a two flavor scenario are sin2 2θm= 1 and Δm2 = 0.0023 eV2. This result is independent of the absolute normalization of the atmospheric neutrino fluxes. The data can also be used to put experimental constrain on this normalization

    Muon astronomy with the MACRO detector

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    We have analyzed a sample of 1.8 x 10(6) muons with E(mu) greater-than-or-similar-to 1.3 TeV collected by the first and second supermodules of the MACRO detector at Gran Sasso during the period 1989 February to 1991 February. We have searched for an excess of muons of celestial origin over cosmic-ray background. Our search for steady sources in solid angle bins of DELTAOMEGA almost-equal-to 3.0-degrees x 3.0-degrees in the declination range -5-degrees less-than-or-equal-to delta less-than-or-equal-to 90-degrees was negative; the upper limit with 95% C.L. to the muon flux at mid-latitudes (delta approximately 45-degrees) is J(mu)steady less-than-or-similar-to 2 x 10(-12) cm-2 s-1. In addition, we have searched for muon excesses modulated by the orbital period of selected X-ray sources, including Cyg X-3, Cyg X-1, Her X-1, 4U 0115+63, and 4U 1907+09. For Cyg X-3 we obtained an upper limit with 95% C.L. of J(mu)mod less-than-or-equal-to 8.8 x 10(-13) cm-2 s-1. Further, we have no evidence of any bursting activity from Cyg X-3, during our search period, which includes the radio outburst of 1991 January

    MUON ASTRONOMY WITH THE MACRO DETECTOR

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    We have analyzed a sample of 1.8 x 10(6) muons with E(mu) greater-than-or-similar-to 1.3 TeV collected by the first and second supermodules of the MACRO detector at Gran Sasso during the period 1989 February to 1991 February. We have searched for an excess of muons of celestial origin over cosmic-ray background. Our search for steady sources in solid angle bins of DELTAOMEGA almost-equal-to 3.0-degrees x 3.0-degrees in the declination range -5-degrees less-than-or-equal-to delta less-than-or-equal-to 90-degrees was negative; the upper limit with 95% C.L. to the muon flux at mid-latitudes (delta approximately 45-degrees) is J(mu)steady less-than-or-similar-to 2 x 10(-12) cm-2 s-1. In addition, we have searched for muon excesses modulated by the orbital period of selected X-ray sources, including Cyg X-3, Cyg X-1, Her X-1, 4U 0115+63, and 4U 1907+09. For Cyg X-3 we obtained an upper limit with 95% C.L. of J(mu)mod less-than-or-equal-to 8.8 x 10(-13) cm-2 s-1. Further, we have no evidence of any bursting activity from Cyg X-3, during our search period, which includes the radio outburst of 1991 January
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