Source: Ever-Elusive Neutrinos Spotted Bouncing Off Nuclei for the First Time - Scientific American The new experimental collaboration, known as COHERENT, instead looks for a phenomenon called CEvNS (pronounced “sevens”), or coherent elastic neutrino-nucleus scattering. CEvNS relies on the quantum mechanical equivalence between particles and waves, comparable to ocean waves. The high-energy neutrinos sought by most experiments are like short, choppy ocean waves. When such narrow waves pass under floating debris, they can pick out one leaf or twig at a time to toss around. Similarly, a high-energy neutrino typically picks out individual protons and neutrons with which to interact. But just as a long, slow wave would pick up the whole patch of debris at once, a low-energy neutrino sees the entire atomic nucleus as one “coherent” whole. This dramatically improves the odds of an interaction. As the number of neutrons in the nucleus is increased, the effective target size for the neutrino to hit grows in lockstep not just with that number, but with its square. Of course, once a neutrino and a nucleus collide, the collision must still be detected. The neutrino bounces off and continues its inscrutable wandering but the nucleus also recoils slightly from the impact. That jolt kicks a few electrons out of their orbits around the nucleus and its neighbors. As the electrons fall back into place, they release their acquired energy as photons. Each burst of photons is the calling card of a neutrino. Impressive! Bob Wilson
The idea that low-energy neutrinos might be easier to detect is counter intuitive. To people like me who have limited interaction cross section with advanced physics. But the SciAm authors explain it well.
