Detecting Fast Time Variations in the Supernova Neutrino Flux with Hyper-Kamiokande

TL;DR

This paper investigates whether Hyper-Kamiokande's detailed energy information can improve detection of rapid supernova neutrino flux variations, finding that energy-dependent oscillations may enhance detection under certain conditions.

Contribution

It introduces a simulation-based analysis of energy-dependent supernova neutrino flux oscillations and establishes conditions where energy binning improves detection prospects.

Findings

Energy-dependent SASI oscillation amplitudes observed.

Energy binning can be advantageous if mean neutrino energy oscillations increase.

Lower event rates in some energy bins limit detection of flux variations.

Abstract

For detection of neutrinos from galactic supernovae, the planned Hyper-Kamiokande detector will be the first detector that delivers both a high event rate (about one third of the IceCube rate) and event-by-event energy information. In this thesis, we use a three-dimensional computer simulation by the Garching group to find out whether this additional information can be used to improve the detection prospects of fast time variations in the neutrino flux. We find that the amplitude of SASI oscillations of the neutrino number flux is energy-dependent. However, in this simulation, the larger amplitude in some energy bins is not sufficient to counteract the increased noise caused by the lower event rate. Finally, we derive a condition describing when it is advantageous to consider an energy bin instead of the total signal and show that this condition is satisfied if the oscillation of the mean neutrino energy is increased slightly.