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Two USD physicists chosen to bring light to dark matter discussion

VERMILLION, S.D. -- Two physicists from the University of South Dakota are primary investigators for two of the three critical dark matter search experiments selected by the Department of Energy (DOE) and the National Science Foundation (NSF).

Joel Sander, Ph.D., assistant professor of physics, is part of the SuperCDMS collaboration along with Dongming Mei, Ph.D., associate professor of physics, who is part of the LZ collaboration that will be located in the Sanford Underground Research Facility (SURF) in western South Dakota.

“Nobody knows what dark matter is made of even though there’s strong evidence that dark matter exists,” explained Sander, who earned his Ph.D. at the University of California, Santa Barbara. “There is a lot of competition to be the one to discover the dark matter.”

The collaborations that Sander and Mei are a part of are racing to begin constructing their experiments as soon as possible. SuperCDMS, which uses germanium detectors cooled to very low temperatures, and LZ, which uses liquid xenon, were chosen from among multiple other experiments for the federal funding targeted toward dark matter discovery.

“The LZ liquid xenon volume would consist of seven tons of liquid xenon, and would also be installed in the Davis Laboratory, in the LUX water tank,” Mei described. “An acrylic vessel filled with Gadolinium doped liquid scintillator (Gd-LS) surrounds the inner titanium cryostats, which contain liquid xenon. This will allow the capability of delivering the first statistically significant and definitive discovery of Dark Matter if Weakly Interacting Massive Particles (WIMPs) are the candidates of dark matter.”

These two experiments will have the greatest opportunity of observing a dark matter signal. Sander says about 80 percent of the mass in the universe is composed of dark matter and while dark matter has eluded discovery for about 80 years, the next several years of in the search for dark matter could be some of the most interesting.

“LZ experiments use light in order to detect dark matter while SuperCDMS experiments utilize sound,” Sander described. “Trying to be able to detect one nucleus getting hit by a dark matter particle, with CDMS you will hear the sound of one nucleus getting hit opposed to LZ where you will see it happen with light.”

According to Sander, the experiments will take a couple of years to set up and will search for dark matter for about five or six years. For two USD scientists (out of three experiments total) to be at the forefront of a possible dark matter discovery is not lost on Sander. It’s an exciting day in physics and he admits that it’s a great distinction for the USD Department of Physics.

“To astro-particle physics and physics in general, this is a really big deal,” he said. “Fortunately for us, they picked two (experiments) that USD is a part of.”

Download a photo of Sander.

Download a photo of Mei.

Download a photo of the SuperCDMS detector.

Download an image of the LZ detector.


Founded in 1862 and the first university in the Dakotas, the University of South Dakota is the only public liberal arts university in the state, with 202 undergraduate and 78 graduate programs in the College of Arts & Sciences, School of Education, Knudson School of Law, Sanford School of Medicine, School of Health Sciences, Beacom School of Business and College of Fine Arts. With an enrollment of nearly 10,000 students and more than 400 faculty, USD has a 16:1 student/faculty ratio, and it ranks among the best in academics and affordability. USD’s 18 athletic programs compete at the NCAA Division I level.

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Hanna DeLange
USD News