The anisotropy of inverse beta decay and antineutrino detection

Abstract

The anisotropy of the positrons emitted in the reaction $\bar{\nu}_{e}+p\to n+e^{+}$ has to be taken into account for extracting an antineutrino signal in Superkamiokande. For the Sun, this effect allows a sensitivity to $\nu_{e}\to\bar{\nu}_{e}$ transition probability at the 3% level already with the statistics collected in the first hundred days. For a supernova in the Galaxy, the effect is crucial for extracting the correct ratio of $\nu-e$ to $\bar\nu_{e}-p$ events.