Passive detector for measurement of the implanted 210Po activity in glass

It is a well known fact that radon is the most important factor in the natural radiation background. For complete dose calculations we need information about the radon concentration up to 25 years ago. As suggested by C. Samuelsson et al. in 1988, the activity of the implanted radon daughter 210Po can be used to reconstruct the radon activity over the past decades. For large scale surveys in dwellings a passive detector based on polycarbonate foils has been investigated. This system has a sufficient sensitivity to detect 210Po levels down to 1 Bq/[m.sup.2] with a 6 month measuring period.