Physicists build the world’s smallest neutrino detector to observe the elusive interaction for the first time. Such an occurrence was first predicted in theory 43 years ago, but had so far eluded scientists.
Neutrinos are a challenge to study because their interactions with matter are so rare. Particularly elusive coherent elastic neutrino-nucleus scattering, which occurs when a neutrino bump off the nucleus of an atom.
The results of the experiment, conducted at the Oak Ridge National Laboratory (ORNL). Previously, researchers only seen interacting with individual protons or neutrons in the nuclei of atoms.
Typically, neutrino detectors huge and look for neutrinos emitted from far away sources like the Sun, and some artificial, like the T2K experiment, where neutrinos sent over 295 kilometers (183 miles) to a detector the size of a building. The more distant these detectors are, the more easily the properties of neutrinos can be measured.
However, this experiment uses a detector that weighs 14.5 kilograms (32 pounds), and the neutrinos emitted are a byproduct of an instrument called the Spallation Neutron Source (SNS) from the target. Although, the detector 100 times more likely to detect neutrinos compared to the observatories that study solar neutrinos.
The energy of the SNS neutrinos almost perfectly tuned for this experiment to create a detectable signal, but small enough to take advantage of the coherence condition.
The measured observation is consistent with predictions of the Standard Model, which is a testament to how good the theoretical foundation of particle physics is. However, this result also has consequences in astronomy. Supernova explosions release a huge amount of neutrinos, which interact with the gas release by the dying star.
Understanding the process feeds into understanding of how these dramatic events occur, said, physicist Kate Scholberg of Duke University. When such an event occurs in the Milky Way, neutrinos of all flavors will bump into nuclei, and sensitive dark matter detectors may observe a burst of tiny recoils.
Researchers now conduct the experiment with different type of detectors to improve the understanding of the phenomenon and learn more about the structure of the nucleus.
More information: [Science]