Towards a complete reconstruction of supernova neutrino spectra in future large liquid-scintillator detectors

The fortunate observation of the sparse neutrino data from the Supernova 1987A explosion in the Large Magellanic Cloud is a milestone in both neutrino physics and neutrino astronomy. Currently many worldwide neutrino detectors runnning or under construction have better detection capbilities of core collapse supernova neutrinos, which can provide high statistics, good energy resolution and more accurate flavor information. For the future large liquid scintillator detectors, given a typical galactic distance of 10 kpc and typical SN parameters, for instance the JUNO detector will register about 5000 events from the inverse beta decay (IBD), $\bar{\nu}_{e}+p \rightarrow n+e^{+}$, 2000 events from all-flavor elastic netrino-proton scattering, as well as more than 300 events from neutrino-electron scattering, and the charge current and neutral current interaction of neutrinos on the $^{12}$C nuclei. In this poster, we propose a more realistic and accurrate reconstruction of supernova neutrino energy spectra in the large liquid scintillator detectors with the singular value decomposition (SVD) unfolding method. Then combining the IBD channel with the other two full flavor elastic scattering channels $\nu+p \rightarrow \nu+p$ and $\nu+e^{-} \rightarrow \nu+e^{-}$, we can also separate the flux spectra for different flavor neutrinos. To demonstrate the validity of our approach, we also attempt to reconstruct the neutrino spectra by using the time-integrated neutrino data from the latest numerical simulations of delayed neutrino-driven supernova explosions