Title: LUX/LZ Dark Matter Experiment and Low Energy Calibrations of LUX Detector

Speaker: Dongqing Huang (Brown University)

Abstract

The LUX dark matter experiment is a 350 kg dual-phase time-projection chamber operating at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD, USA from 2013 to 2016. The experiment searches for direct evidence of Weakly Interacting Massive Particles (WIMPs), a favored Dark Matter candidate. With a total exposure of 129 kg.year, LUX sets a 90% CL upper limit on the spin-independent (SI) WIMP-nucleon cross section of 1.1 × 10−46 cm2 at a WIMP mass of 50 GeV.c−2. The LUX experiment also carried out extensive calibrations for a better understanding of both electronic recoil (ER) and nuclear recoil (NR) responses in LXe. LUX achieved absolute energy calibrations of NR down to an energy of 0.7 keVnr using D-D neutron source and ER down to an energy of 186 eV using 127Xe electron capture in LXe. Both represent the lowest-energy ER and NR in situ measurements that have been explored in liquid xenon. The low energy calibrations allow an lower energy threshold for WIMP search and significantly improve LXe TPC sensitivities to low-mass WIMPs.

I will also present the LUX-ZEPLIN (LZ) detector, a LXe dark matter detector featuring more than 5 tons of target material in the fiducial region (from a total of 10 tons of xenon). It will be installed at the same facilities used by LUX. With a projected exposure of 1000 days (commissioning starts in 2020), LZ aims to exclude the WIMP-nucleon SI cross-sections down to 1.6×10−48 cm2 (90% CL, MWIMP = 40 GeV.c−2). This represents a factor of 10 improvement when compared to the expected sensitivities of currently running LXe dark matter experiments