Study of a discriminative technique between radon and thoron in the Radout detector

Radon is a gaseous alpha emitter radionuclide deriving from the primordial radioactive nuclides present on Earth. Although only 222Rn isotope is commonly considered in radon pollution surveys, there is another isotope, 220Rn, also called Thoron, that is dangerous for human health. In this work these two radon isotopes discrimination is investigated, using a solid-state nuclear track detector (SSNTD) based passive detector named Radout. Experimental exposures to 220Rn and 222Rn were performed and the CR-39 SSNTDs, placed in the Radout detector, were chemically etched and analysed with the automatic track detector reader Politrack®. The analysis of track morphology performed by Politrack® allows to measure the reduced etch rate V for each track. The distributions of V have different shapes for 220Rn and 222Rn exposure, permitting to define a distribution parameter indicative of the presence of 220Rn. The experimental data are compared with a computational model that calculates the expected V distributions produced by the two radionuclides. The agreement of the model with the experimental data is very satisfactory