KM3NeT/ORCA is a megaton-scale underwater Cherenkov detector optimised for the neutrino mass hierarchy determination achieved by measuring the energy and zenith-angle dependent oscillation pattern of few-GeV atmospheric neutrinos. Event reconstruction is a key task and the achieved performance substantially affects the mass hierarchy sensitivity. The excellent optical properties of deep-sea water allow for accurate reconstruction of both shower-like (mostly electron-neutrinos) and track-like events (mostly muon-neutrinos).
This paper describes the key ingredients of the expected neutrino detection performance of ORCA. A focus is put on the methodology and performance of the reconstruction for shower-like events. In addition, the track-shower separation capability is presented.