The gamma background flux below 3000 keV in the Laboratori Nazionali del Gran Sasso ( LNGS ) , Italy , has been measured using a 3 ” diameter NaI ( Tl ) detector at different underground positions : In hall A , hall B , the interferometer tunnel , and inside the Large Volume Detector ( LVD ) .
The integrated flux is 0.3–0.4 s ^ { -1 } cm ^ { -2 } at the first three locations , and is lower by two orders of magnitude inside LVD .
With the help of Monte Carlo simulations for every location , the contribution of the individual primordial isotopes to the background has been determined .
Using an 11 ” diameter NaI ( Tl ) detector , the background neutron flux in the LNGS interferometer tunnel has been estimated .
Within the uncertainties , the result agrees with those from other neutron measurements in the main halls .