The experimental searches for supernova relic neutrino are conducted below 30 MeV, where atmospheric neutrino interactions are the dominant background. Neutrino interactions in this low energy region have a large uncertainty due to complicated nuclear effects, for example, a momentum distribution of a nucleon in nucleus, Pauli blocking and de-excitation of a residual nucleus. Sophisticated neutrino event generators GENIE, NEUT and NuWro provide several models to predict the momentum and Pauli blocking, however, they usually do not treat the de-excitation.
It is very important to carry out a systematic study to predict the contribution of de-excitation, especially for liquid scintillator detectors like KamLAND, Borexino and JUNO since they are sensitive to measure the spectra of not only gamma-ray, but also proton, neutron, alpha.
This poster will present the study on de-excitation associated with neutrino-carbon interaction using TALYS and Geant4. TALYS which is an open source software package to simulate nuclear reactions is used to calculate branching ratios of gamma, proton, neutron and alpha emissions from excited state of residual nucleus. Geant4 is widely-used simulator, and especially G4RadioactiveDecay is a smart tool to trace decay chain event by event.
By combining two softwares, I predicted various branching ratios and spectra of produced particles via de-excitation.The relative errors for the branding ratios are also discussed using another estimation which was carried out by using SMOKER. This prediction does not depend on neutrino event generator, thus, the results can be flexibly applied to the output of all neutrino event generators mentioned above.