Because neutrinos interact with matter via weak interaction, typical neutrino detectors have giant size like a few tens of kilo ton water cherenkov detector. This detector observed neutrino interactions with electrons in the atomic shell. However, there is another type of neutrino interactions with protons/neutrons in the nucleus coherently. In this case, interaction probability is substantially increased, but deposited energy is extremely small. This process was predicted in the 1970s but, was first observed at 2017 by the COHERENT experiment using spallation neutron beam. However, complementary measurements with about 10 times lower energy neutrinos at nuclear reactors are not achieved due to requirements of much lower energy threshold. Observation of coherent scattering from reactor electron antineutrinos will open a new window for a precision understanding of particle physics. This process also can be used for the monitoring of nuclear activities with small detector.
