New neutrino source for the study of solar neutrino physics in the vacuum-matter transition region

Production of a neutrino source through a proton-induced reaction is studied by using the particle transport code geant4. Unstable isotopes such as Si27 can be produced when the Al27 target is bombarded by 15-MeV energetic proton beams. Through the β-decay process of the unstable isotope, a new electron-neutrino source in the 0-5.0 MeV energy range is obtained. Proton-induced reactions are simulated with JENDL-4.0 High Energy File (JENDL-4.0/HE). For radioactive decay processes, we use the G4 radioactive decay model based on the Evaluated Nuclear Structure Data File (ENSDF). We suggest detailed target systems required for future solar neutrino experiments, in particular for the vacuum-matter transition region. As for a detection system of the new neutrino source, we evaluate reaction or event rates for available radiochemical detectors and Low Energy Neutrino Astronomy (LENA)-type scintillator detector and discuss effects due to possible sterile neutrinos as an application.