After 43 years, gentle touch of a neutrino is finally observed

Enlarge / The neutron source at Oak Ridge National Lab. (credit: Oak Ridge National Lab)

Neutrinos are noted for being extremely reluctant to interact with other matter. While it's possible to build hardware that will detect them, these detectors tend to be enormous in order to provide sufficient material for the neutrinos to interact with. Those interactions also take the form of energetic events that transform the identity of particles (for example, converting protons to neutrons).

Given the neutrino's low mass and tendency not to interact, the idea of detecting one simply bumping into another particle seems almost ludicrous. But that's what scientists from Oak Ridge National Lab are reporting today. They've seen brief flashes as atoms get nudged by a neutrino, which imparts a tiny bit of its tiny momentum to the atom's nucleus.

Oak Ridge National Lab is home to some hardware called the Spallation Neutron Source. This accelerates a beam of protons and smashes them into a tank of mercury. This creates debris that includes lots of neutrons, which are used for a variety of scientific purposes. But the debris also includes some neutrinos that are otherwise lost in the spray of particles that comes flowing out of the collisions.

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