Speaker
Description
The LUX-ZEPLIN (LZ) detector consists of 7 tonnes (5.6 tonnes fiducial) of liquefied xenon in a
dual-phase Time Projection Chamber (TPC), which is sensitive to the nuclear and electron recoils
induced by Weakly Interacting Massive Particles (WIMPs). Among the various type of background
particles, neutrons pose a great threat to the WIMPs searches due to the indistinguishable nuclear
recoil. Surrounding the liquid xenon cryostat is an Outer Detector veto system with the primary
aim of vetoing neutron single-scatter events in the liquid xenon. The Outer Detector consists of
approximately 17 tonnes of gadolinium-loaded liquid scintillator (Gd-LS) confined to acrylic tanks
surrounding the cryostat and 228000 litres of water as the outermost layer. The volume is monitored
by 120 inward-facing 8-inch photomultiplier tubes. The Outer Detector is used to characterize the
external background, increasing the fiducial volume of LZ by 70%. I will present the design and
performance of the LZ Outer Detector.
