Domestic census on measurements by liquid scintillation counters. Questionnaire survey of 56 laboratories working for monitoring of environmental radioactivity

Main target medias were seawater, river water, tap water and ambient samples and most of laboratories operated one liquid scintillation counter for measuring mainly 3H and 14C. Relationship between background count rate(B) and efficiency of counting(E) was observed in the distribution of the reported data, a few laboratories showing both lower background counting rate and higher efficiency, which indicates higher figure of merit derived by E2/B. Figure of merit ranged from 63 to 443. Since almost all the laboratories used commercially available standards, the comparability of the liquid scintillation measurements were ensured. Efforts to lower background counting rate were mainly carried out by counter manufactures. (author)