Abstract
In measuring α ray spectra of radioactive airborne dust collected on a filter paper, the presence of α emitters to be detected is masked out by Rn and Tn daughters in atomosphere. Contributions of Tn daughters to α ray spectra of airborne radioactive materials were evaluated for two types of cellulose asbestos filter paper, HE-40 (Toyo) and HV-70 (Honing Worth & Vose), employed in routine air sampling, using the TMC 1024 pulse height analyzer with a silicon semiconductor detector. The distribution was also examined by α counting of thin stripped fragments of the filter paper, and was found to be exponential. On the basis of the results obtained, the collection efficiency of HE-40 and the absorption of α particle in the filter paper are discussed.
