Update on sterile neutrino research

The following excerpts from the Los Alamos National Laboratory website give us an update on the status of sterile neutrino research. [As an aside: Elder Brother spent the last 12-15 years of his career at Los Alamos. He was, however, in the weapons area.]

Los Alamos experiment at Fermilab explores potential ‘dark matter’ link, confirms earlier experiment

LOS ALAMOS, N.M., June 6, 2018—New research results have potentially identified a fourth type of neutrino, a “sterile neutrino” particle. This particle provides challenges for the Standard Model of particle physics, if found to be a valid result in future experiments. The work, conducted by a multi-institutional team at Fermi National Accelerator Laboratory (Fermilab) near Chicago, confirms results found in the 1990s in the Los Alamos Liquid Scintillator Neutrino Detector (LSND).

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Neutrinos, traditionally understood to come in three “flavors,” electron, muon and tau, have been measured by the Mini Booster Neutrino Experiment (MiniBooNE) for some 15 years. The key to the current result is the existence of more electron-flavored neutrinos than expected. Neutrinos normally oscillate between the three types, but the overpopulation of the electron-flavored ones leads to a theory that some of the muon neutrinos became sterile neutrinos for a time during the regular oscillations. The sterile neutrinos could reasonably be assumed to have transitioned into electron neutrinos in their next oscillation phase, thus explaining the higher electron numbers.

“We cannot say definitively that it’s sterile neutrinos, but we can conclusively say something fundamental is going on,” said Richard Van de Water, the Los Alamos co-lead on the project.

This is how you do science

“Over the past 20 to 30 years, neutrino oscillations have been observed from one flavor to another,” he said. “But in the late 1990s the LSND at Los Alamos saw evidence of electron neutrinos in the beam, and if our observations were correct, a much heavier type of neutrino was also in existence. That’s where the idea of sterile neutrinos came about. So the MiniBooNE experiment, designed very differently from LSND, has shown that the results were valid. But this is how we do science—you have an effect, and you build a new experiment to test the original physics effect. This passes muster; it must be something new.”

“I’m careful about saying it’s sterile neutrinos. It could be, but it could be something else. The same effect has now been observed in two experiments, with a small chance that is is a mistake in both experiments. We still see what shouldn’t be there, and it could be even more exciting. Speculating, I like to think of this as the first hint of the dark sector, perhaps interacting through neutrinos, and this could be a way to probe dark matter and dark energy,” Van de Water said.

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More information concerning neutrinos may be found at Fermi National Accelerator Laboratory's All Things Neutrino.

Comments

[Joared]

We should always be interested in anything present that shouldn’t be there, anywhere. I am unable to fully grasp the significance of dark matter as a lay person not steeped in knowledge beyond the mere basics of physics, but I’m fascinated by the mystery of it all. I’m curious about how discovering the properties and functions of dark matter will impact our understanding of our universe. Surely if we’re going to be outer space traveling we need to decipher this puzzle. Sounds like these neutrinos are a meaningful step in that direction.