Dark matter lab in VIC gold mine detects first ‘muons’

Researchers at the Stawell Underground Physics Laboratory (SUPL) in Victoria have detected the first transmissions from a muon detector inside the mine within the first few days of operating.

The muon detector recorded about five detections per day, far lower than the millions of interactions that would be expected above ground.

This is an exciting step for a laboratory which is 1 km underground in an active gold mine in Victoria. The project has been in the pipeline for more than a decade, in the search for elusive dark matter.

“Our first data collections showed that by building the laboratory 1km underground in Stawell Gold Mine, we have managed to reduce the cosmic radiation that will reach our dark matter detector,” says ARC Centre of Excellence for Dark Matter Particle Physics Director Professor Elisabetta Barberio.

“Our scientists in Melbourne and around Australia will be able to continue to monitor muon levels to ensure cosmic radiation remains low.

“It is a very significant step in the project that scientists around the world are watching very closely.”

While stage one was complete last year the team are yet to insert the dark matter detector.

This state-of-the-art detector will be able to measure any weakly interacting massive particles, or WIMPs.

WIMPs are one of our best bets for dark matter, but most dark matter detectors have struggled to find any particles that act like a WIMP.

Dark matter is hard to find. It is thought to make up 80 percent of the matter in the Universe, and galaxies would just fall apart without this unseen gravitational force.

But understanding what dark matter is has been much harder.  Researchers hope that the Stawell detector, and its counterpart in the Northern Hemisphere, may be able to help find WIMPS, and confirm dark matter.

But for the moment, muons are thrilling enough for the researchers.

“It’s really exciting that we can read the cosmic radiation levels deep underground while sitting at our desks at Melbourne University,” said University of Melbourne PhD candidate Mike Mews, who has undergone training to work underground for extended periods. 

“I’m looking forward to travelling to SUPL more regularly as the project continues to progress and we create the ideal environment for the SABRE South experiment.”

You can find out more about SUPL and SABRE South in Issue 94 of Cosmos Magazine, or in Best Australian Science Writing 2022.

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