RSAA Colloquium

Searching for Dark Matter Deep Underground: Tales from Two Gold Mines

Searching for Dark Matter Deep Underground: Tales from Two Gold Mines Direct detection experiments seek to observe rare interactions between dark matter particles and ordinary matter, requiring extreme sensitivity and deep underground locations to shield against cosmic-ray backgrounds. The two dark matter searches I will introduce in this talk happen to share an unusual home: gold mines. LUX-ZEPLIN (LZ) is located 1.5 km underground at the Sanford Underground Research Facility, in a decommissioned gold mine in Lead, South Dakota. The experiment uses a dual-phase time projection chamber containing 7 tonnes of active liquid xenon and, during its 1000-day science run, aims to probe WIMP-nucleon spin-independent cross sections down to about 1.4 × 10⁻⁴⁸ cm² for a 40 GeV/c² WIMP. I will give an overview of the experiment, its current status, and recent results, including world-leading dark matter search limits and the detection of Boron-8 solar neutrinos. 

I will also discuss SABRE South, Australia’s first underground dark matter experiment. It is part of an international collaboration with twin detectors in the Northern and Southern Hemispheres (SABRE North and South). SABRE aims to exploit its dual-hemisphere design to help distinguish possible dark matter signals from seasonal backgrounds, a strategy that is only possible with a southern-hemisphere experiment. SABRE South is housed at the new Stawell Underground Physics Laboratory (SUPL), located 1024 m underground within the still-active Stawell Gold Mine in regional Victoria, Australia. I will provide an overview of the experiment’s current status and expected reach.