By Natalie Wolchover
The physicists who run the world’s most sensitive experimental search for dark matter have seen something strange. They have uncovered an unexpected excess of events inside their detector that could fit the profile of a hypothetical dark matter particle called an axion. Alternately, the data could be explained by novel properties of neutrinos.
More mundanely, the signal could come from contamination inside the experiment.
“Despite being excited about this excess, we should be very patient,” said Luca Grandi, a physicist at the University of Chicago and one of the leaders of the 163-person experiment, which is called XENON1T. The experiment’s successor will be needed to rule out possible contamination from tritium atoms, Grandi said. That experiment is expected to begin later this year.
Outside experts say that whenever there’s a boring explanation, it’s usually right. But not always — and the mere possibility that XENON1T has made a discovery merits attention.
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