Search for High-Energy Neutrinos from SN1987A: First Six Months

Upward-going muons with energy greater than 1.7 GeV produced in the nearby rock by neutrinos from SN1987A were searched for in a 2140-ton underground water Cherenkov detector, Kamiokande II. No upward-going muons from the direction of SN1987A were found from 23 February 1987 to 1 September 1987; the 90%-confidence-level flux limit is 1.2\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}13}$ ${\mathrm{cm}}^{\ensuremath{-}2}$ ${\mathrm{s}}^{\ensuremath{-}1}$ for an energy threshold of 1.7 GeV. For neutrino energy greater than 1.7 GeV, limits on the SN1987A neutrino flux and luminosity are 2.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}5}$ ${\mathrm{cm}}^{\ensuremath{-}2}$ ${\mathrm{s}}^{\ensuremath{-}1}$ and 1.6\ifmmode\times\else\texttimes\fi{}${10}^{41}$ erg ${\mathrm{s}}^{\ensuremath{-}1}$ for cutoff energy ${E}_{c}={10}^{15}$ eV and spectral index $\ensuremath{\gamma}=2.1, \mathrm{and} 2.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3} {\mathrm{cm}}^{\ensuremath{-}2} {\mathrm{s}}^{\ensuremath{-}1} \mathrm{and} 4.6\ifmmode\times\else\texttimes\fi{}{10}^{42} \mathrm{erg} {\mathrm{s}}^{\ensuremath{-}1}$ for ${E}_{c}={10}^{12}$ eV and $\ensuremath{\gamma}=2.7$.