Speaker
Description
The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC in the Davis cavern at the Sanford Underground Research Facility, Lead, South Dakota, 4850 feet below the surface. The underground environment reduces the cosmic ray flux by a factor of $10^6$, but there remains a potential background from $\gamma$-rays emitted from the decays of $^{40}$K, $^{238}$U and $^{232}$Th naturally occurring in the rock surrounding the laboratory. In-situ $\gamma$-ray measurements were taken with a sodium iodide detector in several locations within the cavern, yielding average radioactivity levels. We will present the radioactivity levels determined with these measurements, along a first attempt at mapping non-uniformities in the $\gamma$-flux due to differences in rock composition.
