Low-level liquid scintillation counting in an underground laboratory

A commercial liquid scintillation counter (LSC) was tested for its ability of low level counting (LLC) in two underground laboratories (70m of water equivalent cover). Reduction of total background and background components compared to the normal counting laboratory (5m w.e. cover) up to a factor of 9 depending on the energy range and the shielding of counting cell and laboratory walls were obtained. First experiments with a large volume cell (50cc) led to a modern 14C net effect of 425cpm and a corresponding background of 1.6cpm