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Volume 358 - 36th International Cosmic Ray Conference (ICRC2019) - NU - Neutrino
Observation of Optical Transients and Search for PeV-EeV Tau Neutrinos with Ashra-1
S. Ogawa
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Pre-published on: 2019 July 24
Published on:
Abstract
We report the updated observational search for tau neutrinos ($\nu_{\tau}$) using one of the Ashra light collectors, which faces to Mauna Kea,on Mauna Loa at 3300m above sea level on Hawaii Island. The earth-skimming $\nu_{\tau}$ technique of imaging Cherenkov $\tau$ showers was applied as a detection method. We checked the detection sensitivity and the reconstruction procedure for the Cherenkov $\tau$ shower well with sufficient statistics, i.e. 824 events of ordinary cosmic-ray air-shower Cherenkov images for a total of 1884 hours using the same instruments, but triggered with the attached trigger pixel layout to view the sky field above the mountain. The analysis of about 1863 hours of data taken towards the mountain of Mauna Kea and the Earth crust around it leads to a 90\% C.L. point source limit for ${\nu_{\tau}}$ in the energy range from 3PeV to 10EeV of about $\mathrm{E}^{2}_{\nu_{\tau}}\cdot\phi(\mathrm{E}_{\nu_{\tau}}) < 3.2 \times 10^{-7}~\mathrm{GeV}~\mathrm{cm}^{-2}~\mathrm{s}^{-1}$
assuming power-law $\nu$ spectrum with the index of -2. The analysis status of about 5783 hours of optical transients data is also presented.
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