3,263 research outputs found

    Seasonal variations of the rate of multiple-muons in the Gran Sasso underground laboratory

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    It is well known that the rate of cosmic ray muons depends on the atmospheric temperature, and that for events with a single muon the peak of the rate is in summer, in underground laboratories in the northern hemisphere. In 2015 the MINOS experiment, in USA, found that, for small distances between the multiple-muons, the rate of multiple-muons peaks in the winter and that the amplitude of the modulation is smaller than in the case of a single muon. I have done a re-analysis of data of the past MACRO experiment. The result is that under Gran Sasso the rate of multiple-muons at small distances peaks in the summer. This difference with MINOS could be explained by differences in the atmospheric temperature due to latitude. This results could be of interest for dark matter experiments looking to dark matter seasonal modulation due to the Earth's motion.Comment: presented to the RICAP 2016 conferenc

    Search for a possible space-time correlation between high energy neutrinos and γ\gamma-ray bursts

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    We look for space-time correlations between 2233 gamma-bursts in the Batse Catalogs and 894 upward-going muons produced by neutrino interactions in the rock below or inside MACRO. Considering a search cone of 10 degrees around GRB directions and a time window of 200 s we find 0 events to be compared to 0.035 expected background events due to atmospheric neutrinos. The corresponding upper limit (90% c.l.) is 0.87 * 10^-9 cm^-2 upward-going muons per average burst

    New distributed offline processing scheme at Belle

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    The offline processing of the data collected by the Belle detector has been recently upgraded to cope with the excellent performance of the KEKB accelerator. The 127/fb of data (120 TB on tape) collected between autumn 2003 and summer 2004 has been processed in 2 months, thanks to the high speed and stability of the new, distributed processing scheme. We present here this new processing scheme and its performance.Comment: 4 pages, 8 figures, uses CHEP2004.cl

    Atmospheric Neutrinos

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    The results of experiments on atmospheric neutrinos are summarized, with the important exception of Superkamiokande. The main emphasis is given to the Soudan-2 and MACRO experiments. Both experiments observe atmospheric neutrino anomalies in agreement with nu_mu-->> nu_tau oscillations with maximum mixing. The nu_mu-->> nu_sterile oscillation is disfavored by the MACRO experiment.Comment: To be published in the proceedings of TAUP99 Conference College de France - Paris 6-10 September 1999 11 pages 12 figure

    Quark nuggets search using 2350 Kg gravitational waves aluminum bar detectors

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    The gravitational wave resonant detectors can be used as detectors of quark nuggets, like nuclearites (nuclear matter with a strange quark). This search has been carried out using data from two 2350 Kg, 2 K cooled, aluminum bar detectors: NAUTILUS, located in Frascati (Italy), and EXPLORER, that was located in CERN Geneva (CH). Both antennas are equipped with cosmic ray shower detectors: signals in the bar due to showers are continuously detected and used to characterize the antenna performances. The bar excitation mechanism is based on the so called thermo-acoustic effect, studied on dedicated experiments that use particle beams. This mechanism predicts that vibrations of bars are induced by the heat deposited in the bar from the particle. The geometrical acceptance of the bar detectors is 19.5 m2\rm m^2 sr, that is smaller than that of other detectors used for similar searches. However, the detection mechanism is completely different and is more straightforward than in other detectors. We will show the results of ten years of data from NAUTILUS (2003-2012) and 7 years from EXPLORER (2003-2009). The experimental limits we obtain are of interest because, for nuclearites of mass less than 10410^{-4} grams, we find a flux smaller than that one predicted considering nuclearites as dark matter candidates.Comment: presented to the 33rd International Cosmic Ray Conference Rio de Janeiro 201
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