Example for an anti-electron neutrino energy spectrum with α = 2.92 predicted for an 8.8 solar mass O-Ne-Mg core supernovae collapse (Hüdepohl et al. 2010) one second after the onset of the burst (solid line). Also shown is the cross section weighted energy spectrum of produced positrons and electrons from inverse beta decay (dashed line) as well as a measure of the detectable energy, which is proportional to the number of Cherenkov photons N_γ in the (300–600) nm range (dotted line). The relation N_γ = a·E_e with a = 178 MeV^-1 is used.