Improvement of sensitivity of thoron monitoring with electret

The sensitivity of thoron monitoring method can be improved largely by applying an electrostatic field in the sampling chamber of thoron dosimeter because more than 90% of the thoron progenies are positively charged at the moment when they generate. The paper introduces a sensitive thoron monitoring method by both using electret to produce electrostatic field in the sampling chamber and using CR-39SSNTD to record α particles emitted from thoron and its progenies. Compared to normal Simultaneous and absorber methods, the new method presents 8 and 33 times sensitivity for thoron monitoring, respectively.