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 gamma s(-1). The arithmetic mean was 49 gamma s(-1) for measurements taken without a collimator. The average gamma flux inside the Lab was 0.25 gamma 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.