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

The CHOOZ experiment has measured the antineutrino flux at about 1 km from two nuclear reactors to search for possible νₑ→νₓ oscillations with mass-squared differences as low as 10^-3 eV² for full mixing. We show that the analysis of the ~2700 νₑ events, collected by our liquid scintillation detector, locates the antineutrino source within a cone of half-aperture ≈18^∘ at the 68% C.L. We discuss the implications of this result for locating a supernova explosion.