A high-sensitivity Rn detector incorporating a particle generator.

A particle generator has been incorporated into a two-filter Rn detector to eliminate plate-out, thus increasing the number of Rn progeny collected on the outlet filter. Recording the activity of this filter by a zinc sulphide screen and photomultiplier has enabled Rn levels as low as 0.05 Bq m-3 to be detected. The theory of operation of the detector and details of the design of a 2-m3 detector are presented, and its performance discussed.