Abstract
It is important to study the behavior of recoiling radon atoms Rn-222 after decay of parent Ra-226 and the effect of parameters on their access to the surrounding medium. The present study was carried out using CR-39 detector to study the effect of grain size on the correlation between surface and mass exhalation rates and the correlation between emanation coefficient and exhalation rate at different masses of soil and phosphate fertilizer. In addition, the relationship between emanation coefficient and the sample mass was studied for different grain sizes (0.1, 0.3, 0.5 and 1 mm). The results showed that there is no effect of grain sizes on the correlation coefficient between surface and mass exhalation rates in soil and fertilizer. The correlation coefficient between emanation coefficient and exhalation rate in different masses of soil was slightly influenced by the grain sizes. While the correlation coefficient between emanation coefficient and exhalation rate in different masses of phosphate fertilizer samples was not affected by the grain sizes (0.1, 0.3 and 0.5 mm). However, it was found that the emanation coefficient decreases exponentially with the mass for soil and phosphate fertilizer. This relationship was not significantly affected by grain size in soil except grain size 1 mm. While this relationship was affected by grain size >0.3 mm in phosphate fertilizer.