What Neutrino Reaction Has a Large Cross-Section?

All reactions that are currently used to detect neutrinos are endothermic (more precisely, endo-energy). They occur at the expense of the energy of neutrino that initiates them. These reactions are characterized by a very small cross-section, which is close in magnitude to the 10−20 barn. Beta decay is an exo-thermal (more precisely, exo-energetic) reaction. Currently, it seems that the entire physical community believes that the beta decay phenomenon occurs completely by accident. However, recent experiments with reactor neutrinos [1, 2] have shown that their flux makes an additional contribution to the beta decay rate. Since beta decay is an exo-energetic reaction, neutrinos catalyze beta-active nuclei without losing own energy (or with a small loss of it). The cross-section of this process is much larger than the cross-section of the endo-energetic interaction of neutrinos with matter. Experimental measurements show that the cross section of reactor neutrinos with 63Ni nuclei is close to 1 barn.