Gamma background measurements in the Gran Sasso National Laboratory

In situ gamma-ray measurements were taken at eight locations in the Gran Sasso National Laboratory (Italy). Count rates for gamma radiation within the energy range of 7-2,734 keV varied from 8 to 60 γ s^-1. The arithmetic mean was 49 γ s^-1 for measurements taken without a collimator. The average gamma flux inside the Lab was 0.25 γ cm^-2 s^-1. The sedimentary rocks surrounding the Lab are characterized by low activity concentrations of uranium and thorium, equal to 1.7 and 1.4 Bq kg^-1, respectively.