Measurement of the Gamma Ray Background in the Davis Cavern at the Sanford Underground Research Facility

Understand

Deep underground environments are ideal for low background searches due to the attenuation of cosmic rays by passage through the earth.

• However, they are affected by backgrounds from $\gamma$-rays emitted by $^{40}$K and the $^{238}$U and $^{232}$Th decay chains in the surrounding rock.
• The LUX-ZEPLIN (LZ) experiment will search for dark matter particle interactions with a liquid xenon TPC located within the Davis campus at the Sanford Underground Research Facility, Lead, South Dakota, at the 4,850-foot level.
• In order to characterise the cavern background, in-situ $\gamma$-ray measurements were taken with a sodium iodide detector in various locations and with lead shielding.