Colloquium: How to Turn a Dark Matter Experiment into a Helioscope?

ABSTRACT

Despite extensive astronomical evidence for dark matter (DM), its direct detection remains elusive. The XENONnT experiment, utilizing a dual-phase xenon time projection chamber, is designed to detect nuclear recoil (NR) signals from scattering between weakly interacting massive particles (WIMPs) and xenon nuclei. To minimize background interference, the detector is located deep underground at the Laboratori Nazionali del Gran Sasso (LNGS) with a 3600-meter water-equivalent rock to shield cosmic rays. Additionally, stringent material selections and xenon purification techniques ensure an exceptionally low radioactive background, establishing XENONnT as the DM detector with the lowest background to date.

This ultra-low background environment also allows XENONnT to explore other physics, such as solar neutrinos and axions. Solar B-8 neutrinos can induce NR signals through coherent elastic neutrino-nucleus scattering (CEvNS), while solar axions produce electronic recoils (ERs). These searches require different background considerations and detection thresholds compared to WIMP searches.

In this talk, I will present these three key results from the XENONnT experiment and discuss its prospects as an observatory for multi-purpose physics.

BIOGRAPHY

Prof. Jingqiang Ye is a tenure-track assistant professor at CUHK-Shenzhen, specializing in experimental particle physics. He received his B.S. in physics from Zhejiang University in 2014 and completed his Ph.D. in physics at the University of California, San Diego in 2020. Following his postdoctoral research at Columbia University, Prof. Ye joined CUHK-Shenzhen in 2024.

His research focuses on the direct detection of dark matter and neutrinos using noble liquid detectors, with an emphasis on advancing technologies for next-generation experiments. Prof. Ye’s group is currently involved in two major experiments: the XENONnT dark matter experiment and the RELICS reactor neutrino experiment. In addition, he leads research and development efforts in his local lab, including the development of new calibration sources and techniques for monitoring and reducing radioactive backgrounds.