The LZ Dark Matter Experiment and Ultra-Low Energy Calibration of Dual-phase LXe TPC Detectors

by Dr Huang Dongqing (University of Michigan)

Tuesday 1 Mar 2022, 10:30 → 11:30 Asia/Shanghai

B105 (CHEP)

The LUX-ZEPLIN (LZ) experiment is a 7 tonnes active mass dual-phase xenon time-projection chamber (TPC) operating at the 1490-meter level of the Sanford Underground Research Facility in Lead, SD, USA. The experiment aims to detect rare events resulting from the scattering of Weakly Interacting Massive Particles (WIMPs), a leading dark matter candidate. Its projected sensitivity for the spin-independent WIMP-nucleon cross section is of 1.4×10-48 cm2 for a 40 GeV/c2 mass WIMP at 1000 live-days exposure with a fiducial mass of 5.6 tonnes. I will present the current status of the LZ experiment. I will also present ultra-low energy calibrations of electronic recoil (ER) using an intrinsic 127Xe source and of nuclear recoil (NR) using a short pulsed D-D neutron generator in the LUX detector (LZ predecessor). Both ER and NR measurements represent the lowest-energy in situ calibrations (0.19 keVee for ER and 0.27 keVnr for NR) that have been explored in liquid xenon (LXe). New calibration results are crucial to determine physics search sensitivities for large mass LXe TPCs (LZ experiment) for low mass WIMPs (< 10 GeV). I will close with presenting a proposal of a new technique for ultra-low energy NR calibration using the recoils imparted to xenon nuclei during the de-excitation process following thermal neutron capture, where the instantaneous gamma cascade leaves the nuclei with less than 0.3 keVnr of recoil energy. I will describe the calibration technique, and the current status of the experiment with the Michigan Xenon (MiX) detector (a small TPC xenon detector at the University of Michigan). Biography: Dongqing Huang (黄栋青) a postdoctoral research fellow at the University of Michigan. He has been an active member of both LUX (Large Underground Xenon) and its successor LZ (LUX-ZEPLIN) dark matter search experiments since 2012. He is currently serving as the deputy coordinator for the LZ background working group. He completed his Ph.D. in physics at Brown University in 2019. He has published more than 30 journal articles and reported science results 18 times in international conferences. Tecent Meeting： https://meeting.tencent.com/dm/NSFHvsQpiLf9 Meeting ID：959-811-073