Estimating retrospective indoor radon concentrations with a new device.

From the (222)Rn mixed with air, the short-lived daughters (218)Po, (214)Pb, (214)Bi, and (214)Po attach to dust particles and are deposited on surfaces where finally (210)Pb and (210)Po are formed. The alpha particles from (210)Po can be measured on surfaces such as window glass or mirrors. The design and construction are presented of a new device using a silicon detector to measure this (210)Po. Some preliminary results are reported and estimates of retrospective radon concentrations are made from them.