USD Reaches Milestone in Dark Matter Research

copy of dark matter. USD researcher Xianghua Meng stands by a Ge detector sputtering machine.

VERMILLION, S.D. – Dark matter research at the University of South Dakota has reached a significant milestone with the creation of the first-ever germanium (Ge) detector built from crystals grown at USD.

In November, physics master’s student Mitch Wagner successfully demonstrated the first detector fabrication technology at USD using a commercial crystal.

“It was fantastic to know I was able to create a Ge detector at USD,” said Wagner. “It was like a dream come true.”

Subsequently, physics postdoctoral student Xianghua Meng, Ph.D., created her own Ge detector using the same process as Wagner but with a twist that verified the work of another research project at USD. She used high-purity germanium crystals grown by research faculty Guojian Wang, Ph.D., and doctoral student Hao Mei.

“I found that making Ge detectors was fabulous,” said Meng. “It is like an art to me.”

Ge detectors are the recognized gold standard for detecting and identifying characteristic gamma rays from nuclear or radiological sources due to their extremely high resolution and sensitivity.

The technology is a well-accepted methodology in the search for dark matter and neutrinoless double-beta decay that is being operated at Sanford Underground Research Facility in Lead, South Dakota.

“This is not easy,” said Dongming Mei, Ph.D., a physics professor and the principal investigator of the project at USD. “It took us seven years to reach this point with many successes and failures.”

With a unique crystal growth facility, USD has helped establish PIRE-GEMADARC, a global collaboration funded by National Science Foundation to consolidate the worldwide efforts of a ton-scale Ge experiment.

“USD has become the 5th player in the world producing Ge detector-grade crystals and making Ge detectors. The other four are companies. USD is the only research institution with this capacity now,” said Mei.

Mei expressed his appreciation for the support received from many governmental organizations and scientific collaborators from around the world. He said a key step was enlisting the help of world renowned expert, Mark Amman, Ph.D., a retired staff scientist from Lawrence Berkeley National Laboratory (LBNL), who taught the USD researchers Ge detector fabrication technology.

“I want to thank the Department of Energy, National Science Foundation, the State of South Dakota, and USD who have all provided strong financial support and a platform to connect with scientists from all over the world,” said Mei.

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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 205 undergraduate and 73 graduate programs in the College of Arts & Sciences, School of Education, 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 17:1 student/faculty ratio, and it ranks among the best in academics and affordability. USD’s 17 athletic programs compete at the NCAA Division I level.

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