August 9, 2022

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Ultra-sensitive dark matter detector just launched

Ultra-sensitive dark matter detector just launched

The LZ central detector in the clean room of the Sanford Underground Research Facility.

The LZ central detector in the clean room of the Sanford Underground Research Facility.
picture: Matthew Capost, Sanford Underground Research Facility

The LUX-ZEPLIN (LZ) Experiment Team announced the results of its first science trial today; The experiment is the world’s most sensitive dark matter detector, and although it didn’t find any dark matter on this first run, the team confirmed that the experiment worked as expected.

The LZ experiment detector consisted of nested tanks of liquid xenon, each 1.5 m high and 1.5 m wide, buried under the south Dakota. The idea is that a dark matter particle passing through space will eventually bounce off one of the xenon atoms, causing electrons to fall out in a flash that was recorded by the experiment. The tank was buried about a mile underground to reduce the amount of background noise. Today’s announcement comes after 60 days of data collection that ran from December 25 to May 12.

“We are looking for very, very low energy bounces by the standards of particle physics. It is a very, very rare process, if it is visible at all,” said Hugh Lippincott, a physicist at the University of California, Santa Barbara and a member of the LZ team, at a press conference today. of dark matter within 10 million light-years of lead and we expect only one interaction at the end of that light-year.”

Dark matter is the general term for unknown things that seem to make up about 27% of the universe. It rarely interacts with ordinary matter, hence its “darkness” for us. But we do know that it exists because, although it is not directly detected, it has gravitational effects that can be seen on cosmic scales. (NASA breaks down well understood over here.)

There are many candidates for dark matter. One is WIMP, or weakly interacting massive particle. Unlike others Dark matter hypotheses such as axes or dark photons, which are so small and scattered that they might act like waves, WIMPs would have mass but rarely interact with ordinary matter. So to discover it, you need a device that pretty much mutes all the other physics going on.

LZ is very sensitive, which makes it good for detecting such transient and infrequent interactions. The experiment is 30 times larger and 100 times more sensitive than its predecessor, the large underground Xenon experiment, according to the Sanford Underground Research Facility. Release. Lippincott said the LZ is an “effective onion,” with each layer of the experiment insulated against noise that could mask a potential interaction with WIMP.

External detector LZ, which protects against unwanted signals.

External detector LZ, which protects against unwanted signals.
picture: Matthew Capost, Sanford Underground Research Facility

“The collaboration worked well together to calibrate and understand the detector’s response,” said Aaron Manalisay, a Berkeley Lab physicist and LZ team member, at Berkeley Lab. press release. “Given that we’ve been running it for a few months now and during the COVID restrictions, it’s really impressive that we’ve had such significant results.”

Of the many discoveries made by the 60-day LZ experiment, 335 seemed promising, but none of them turned out to be WIMPs. That’s not to say WIMP doesn’t exist, but it eliminates a large scope of the controversy. (This is the gist of what dark matter detectors do: little by little, they rule out the mass of the particles I can not is being.) Several physicists recently told Gizmodo They think the next big discovery in particle physics will come from a dark matter detector like LZ.

This scientific race began what is expected to be a 1,000-day timeline. The final round was also unblinded, so Team LZ can monitor how the technology behaves. Since it was working as expected, the next scientific run would have its results “salted” or peppered with spurious signals, for alleviation of bias.

Twenty times more data will be collected in the coming years, so perhaps Wimpy WIMPs will finally have to face the music of their existence. Then again, they may not have been there at all. We won’t know until we look.

More: 10 years after the Higgs boson, what’s the next big thing for physics?

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