Calculating the radioactivity concentration of Cr-39 detectors using the area frequency density function

In this study, a new method for calculating the measurement of saturated radon gas concentration was presented using the area frequency density function, where images of CR-39 samples were analyzed by means of the Image-J program, that were exposed for a whole month to soil samples from different regions of Najaf province-Iraq. The difference in the area between the tracks was adopted due to the possibility of the presence of more than one close trace for alpha particles, which led to the appearance of tracks of a large area as a result of their merging due to the chemical etching process, therefore, the area of the track was taken into account when conducting the counting process by adding a weight factor to correct the counting process based on its area. Preprocessing steps of image samples were carried out by removing defects resulting from the chemical etching process of CR-39 detectors. The study showed an increase in the calculated radon gas concentration by (20%-60%) over its calculated counterpart using manual counting.