Desorption of 220Rn progeny from large surfaces by alpha- and beta-recoil processes.

Transfer (i.e., desorption or detachment) of 220Rn progeny from a substrate (metal disc, filter material, and activated charcoal) to its surroundings has been investigated. The technique, methodology, and materials used differ from the work of others in a number of significant ways. For instance, 220Rn progeny were deposited on substrates by plate-out techniques, and detached 220Rn progeny were measured using a silicon barrier alpha-particle detector as both the host "receiving" surface and the detector for the detached radionuclides. Transfer of 220Rn progeny from the substrates to the detector was observed by alpha- and beta-recoil processes. The latter were demonstrated by using nonadsorbing 220Rn substrates. Other possible mechanisms of 220Rn progeny transfer are also discussed.