Expected neutrino events at Hyper-K in 1 ms time bins, for a Galactic CCSN at a distance of 8.5 kpc. Inverse-beta events are shown by thick blue lines, while the lower thin red lines denote electron scattering events. For each, the three lines show three neutrino mixing scenarios: (i) MSW mixing (central solid lines), (ii) no mixing (upper lines), and (iii) full flavour swap (lower lines). This is done to show the range of possible mixing, accounting for both mass hierarchies, MSW, and collective neutrino oscillations. The MSW mixing line represents normal (inverted) mass hierarchy for |$\bar{\nu }_e$| (νe). The no mixing assumes the observed electron neutrinos are entirely composed of the same flavour at source (i.e. |$\bar{\nu }_e = \bar{\nu }_e^0$| and |${\nu }_e = {\nu }_e^0$|), while the full swap assumes they are entirely exchanged with the heavy flavour states at source (i.e. |$\bar{\nu }_e = {\nu }_x^0$| and |${\nu }_e = {\nu }_x^0$|); see Appendix A1 for details. The inset shows the first 40 ms of the IBD signal at Hyper-K, shown in 2 ms bins, for the MSW mixing case. The error bars are root-N Poisson errors.
