New scientific results confirm an anomaly seen in previous experiments, which may point to an as-yet-unconfirmed new elementary particle, the sterile neutrino, or indicate the need for a new interpretation of an aspect of standard model physics, such as the neutrino cross section, first measured 60 years ago. Los Alamos National Laboratory is the lead American institution collaborating on the Baksan Experiment on Sterile Transitions (BEST) experiment, results of which were recently published in the journals Physical Review Letters and Physical Review C.
“The results are very exciting,” said Steve Elliott, lead analyst of one of the teams evaluating the data and a member of the Los Alamos Physics division. “This definitely reaffirms the anomaly we’ve seen in previous experiments. But what this means is not obvious. There are now conflicting results about sterile neutrinos. If the results indicate fundamental nuclear or atomic physics are misunderstood, that would be very interesting, too.” Other members of the Los Alamos team include Ralph Massarczyk and Inwook Kim.
More than a mile underground in the Baksan Neutrino Observatory in Russia’s Caucasus Mountains, BEST used 26 irradiated disks of chromium 51, a synthetic radioisotope of chromium and the 3.4 megacurie source of electron neutrinos, to irradiate an inner and outer tank of gallium, a soft, silvery metal also used in previous experiments, though previously in a one-tank set-up. The reaction between the electron neutrinos from the chromium 51 and the gallium produces the isotope germanium 71.
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