Approach to discriminatively determine radon and thoron emanation fractions with a scintillation cell

Sakoda, Akihiro   ; Meisenberg, O.*; Tschiersch, J.*

The powder sandwich technique was recently developed to measure thoron (Rn-220) emanation fraction from a sample with high Ra-224 concentration. In this method, a sample was set between two filters, and then air passing through the filters was directly introduced to a detector. In the present study, this technique was expanded to discriminatively measure radon (Rn-222) and thoron emanation fractions using a scintillation cell. First, we made theoretical models that predict counts per time for each nuclide (radon, thoron, or their progeny). Then, analytical solutions for these models were fitted to experimental data to obtain radon and thoron emanation rates. This presentation describes mainly the rationale of our approach. Measurement examples for some samples are also shown and discussed.