Determination of neutrino incoming direction in the CHOOZ experiment and its application to supernova explosion location by scintillator detectors

Abstract

The CHOOZ experiment has measured the antineutrino flux at about $1 \mathrm{km}$ from two nuclear reactors to search for possible ${\overline{\ensuremath{\nu}}}_{e}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{x}$ oscillations with mass-squared differences as low as ${10}^{\ensuremath{-}3} {\mathrm{eV}}^{2}$ for full mixing. We show that the analysis of the $\ensuremath{\sim}2700 {\overline{\ensuremath{\nu}}}_{e}$ events, collected by our liquid scintillation detector, locates the antineutrino source within a cone of half-aperture $\ensuremath{\approx}18\ifmmode^\circ\else\textdegree\fi{}$ at the $68% \mathrm{C}.\mathrm{L}.$ We discuss the implications of this result for locating a supernova explosion.