Australian scientists stalking, sensing and trapping elusive dark matter

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Scientists available for interview from the Physics Congress in Brisbane

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Australian physicists are using all the skills of experienced hunters in their quest for dark matter, the 85 per cent of matter in the Universe we have not been able to detect. And they are getting closer to their quarry.

Members of three separate groups from across the continent will give the latest updates from the hunt at the APPC-AIP Physics Congress in Brisbane.

Dark matter is so called because it does not interact with light or any other electromagnetic radiation. So the physicist hunters need to use all their ingenuity to track it down. 

The stalkers

Maybe we have been looking for the wrong thing, and the evidence is right in front of our eyes. Professor Victor Flambaum and his group at the University of New South Wales have shown that interactions with dark matter can produce changes in the fundamental constants of nature, and it’s been happening since a second or so after the Big Bang.

These interactions leave a characteristic fingerprint in the abundances of Helium in the Universe over time—and that should be easier to detect than the dark matter particles others are chasing, Victor says. In addition to the astronomical observations, the work can also be done using laboratory experiments and, as the research group increases its sensitivity of measurement, they are getting closer to their quarry.

The sensors

The Christmas present Professor Mike Tobar and his group at the University of Western Australia want is evidence of the low-energy dark matter particles known as axions. They have used their considerable expertise in precision measurement to build a laboratory device in which they hope axions will interact with photons of light to produce high-frequency microwaves.

Modelled on a similar experiment at the University of Washington in the US, the West Australian group will be searching a completely different part of the spectrum for axions, at a frequency where there is a strong claim that they should exist—and they’re on the verge of getting this first pathfinder experiment working.

The trappers

A kilometre underground in a working gold mine on the outskirts of Stawell in western Victoria, a multi-institution collaboration of physicists is setting a trap for dark matter particles—an incredibly pure crystal of sodium iodide that will emit a flash of light if a dark matter particle hits the nucleus of one of its atoms.

Professor Anthony Williams of the University of Adelaide will describe their progress. Construction has already begun on the underground laboratory, the first of its kind in the Southern Hemisphere. It will also be used for other low-radiation experiments.

More about the hunt for dark matter, visit the 13th Asia-Pacific Physics Conference and 22nd Australian Institute of Physics Congress at the Brisbane Convention and Exhibition Centre from Monday.

@AsiaAusPhysics #BrisPhys16

The APCC-AIP Congress is the Joint 13th Asia Pacific Physics Conference and the 22nd Australian Institute of Physics Congress incorporating the Australian Optical Society Annual Conference. It’s held at the Brisbane Convention Centre from 4 to 8 December 2016.