Charged-current scattering off $^{16}$O nucleus as a detection channel for supernova neutrinos

TL;DR

This paper evaluates the potential of charged-current interactions with $^{16}$O in Super-Kamiokande to detect supernova neutrinos, analyzing different emission models and nuclear excitation effects to improve spectral diagnosis.

Contribution

It provides detailed cross section calculations for $^{16}$O reactions using shell model results and introduces a simplified method for event spectrum evaluation.

Findings

Higher excitation energies soften the event spectrum by 4-7 MeV.

The study compares ordinary and black-hole-forming supernova models.

A validated simplified approach for spectrum evaluation is proposed.

Abstract

Event spectra of the neutrino-$^{16}$O charged-current reactions in Super-Kamiokande are evaluated for a future supernova neutrino burst. Since these channels are expected to be useful for diagnosing a neutrino spectrum with high average energy, the evaluations are performed not only for an ordinary supernova neutrino model but also for a model of neutrino emission from a black-hole-forming collapse. Using shell model results, whose excitation energies are consistent with the experimental data, the cross sections of the $^{16}$O($\nu_e, e^-$)X and $^{16}$O($\bar\nu_e, e^+$)X reactions for each nuclear state with a different excitation energy are employed in this study. It is found that, owing to the components of the reaction with higher excitation energy, the event spectrum becomes 4-7 MeV softer than that in the case without considering the excitation energies. In addition, a simplified approach to evaluate the event spectra is proposed for convenience and its validity is examined.