Looking for dark matter in a gold mine

Deep underground in rural Victoria, Matteo Volpi is searching for evidence of the cosmic glue that holds the Universe together: dark matter.

Matteo is taking the initial measurements for the study at Stawell Gold Mine where an international team is set to construct a $3.5 million laboratory more than a kilometre underground.

Matteo Volpi is looking for dark matter in the Stawell Gold Mine. Credit: Michael Slezak
Matteo Volpi is looking for dark matter in the Stawell Gold Mine. Credit: Michael Slezak

Understanding dark matter is regarded as one of the most important questions of modern particle physics.

“If we nail it, it’s a Nobel Prize– winning experiment,” says the project leader Elisabetta Barberio, a University of Melbourne physicist and chief investigator of the Australian Research Council Centre of Excellence for Particle Physics at the Terascale (CoEPP).

The lure of detecting dark matter has even drawn the local Northern Grampians Shire Council into assessing the mine’s suitability for the project.

In the 1930s, astronomers recognised that all the matter they could see—the galaxies, stars, planets, dust clouds and comets—did not have enough gravitational pull to hold the Universe together.

This led to the hypothesis of an invisible matter that made up about 85 per cent of all matter in the Universe. This was dubbed dark matter because it doesn’t interact with light.

Since then, the hunt has been on for dark matter particles, which can be detected through their actions as they bump into and move other things.

The physicists at Stawell are hoping dark matter particles will reveal themselves by causing nuclei in sodium iodide crystals to absorb energy and recoil.

To undertake this study, Matteo, a postdoctoral fellow in The University of Melbourne’s School of Physics, and his CoEPP colleagues are collaborating with Princeton University in the US, the Australian Nuclear Science and Technology Organisation and the Italian Institute for Nuclear Physics, which will run a parallel experiment inside an Italian mountain.

For more information: ARC Centre of Excellence for Particle Physics at the Terascale, Caroline Hamilton, caroline.hamilton@coepp.org.au, coepp.org.au

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