Scientists have, for the first ever time, made direct observations of coherent neutrino interaction thereby proving a theory established in 1974.
Scientists have been looking at coherent elastic neutrino-nucleus scattering (CEνNS) as a valuable means to probe the properties of neutrinos, particles with particularly small mass relative to others. Further, CEνNS could yield useful technological applications, such as non-intrusive nuclear reactor monitoring.
The ability to directly observe neutrinos scattering upon impact of an atom’s nucleus has eluded scientists for several reasons, including the technological difficulty in detecting the extremely low-energy recoil of the nucleus, the single outcome of the interaction.
To detect CEνNS, scientists at Oak Ridge National Laboratory exposed the neutrinos to a sample of sodium-doped cesium iodide, which contains ideal-sized nuclei and which generates a sufficient flash of light for the detection of the nuclear recoil upon impact. Their data were taken over the course of 15 months, and adjusted for interactions with other particles.
Typically, neutrinos interact with individual protons or neutrons inside a nucleus. But in “coherent” scattering, an approaching neutrino “sees” the entire weak charge of the nucleus as a whole and interacts with all of it.
Three neutrino flavors were seen by COHERENT–muon neutrinos that emerged instantaneously with the neutron beam and muon antineutrinos and electron neutrinos that came a few microseconds later.
The calculable fingerprint of neutrino-nucleus interactions predicted by the Standard Model and seen by COHERENT is not just interesting to theorists. In nature, it also dominates neutrino dynamics during neutron star formation and supernovae explosions.