Gamma background measurements in the Boulby Underground Laboratory

To determine background radiation levels that might influence experiments, we measured in situ gamma-ray emissions at ten locations in the Boulby Underground Laboratory. For gamma radiation in the energy range of 7–2,734 keV, the counts varied from 6.5 to 28 γ s−1. For measurements inside the Lab, the arithmetic mean was 24 γ s−1. The sedimentary rocks that surrounded the Lab, halite and mudstone, were characterized by very low activity concentrations of uranium (0.8–7.1 Bq kg−1) and thorium (0.6–3.9 Bq kg−1).