Simulating atmospheric neutrino oscillations for neutrino mass hierarchy discovery

The atmospheric neutrino transport through the Earth, including oscillations in the three-active-flavor scheme, has been simulated using the PHAST (particle hard and soft transport) code system, incorporating the Mikheyev-Smirnov-Wolfenstein effect. We investigated the energy range of 0.1-100 GeV, with a fixed $\delta _{CP} = 280^\circ $, for underwater detectors such as KM3NeT/ORCA and IceCube/DeepCore. Preliminary results identify the 3-10 GeV energy range as promising for the future determination of the neutrino mass hierarchy. The neutrino oscillation implementation in PHAST was validated by comparing our oscillograms with those from the KM3NeT collaboration, showing good agreement. Note, that this study assumes ideal detector conditions, without accounting for the detector response. Further details are presented and discussed in the paper.