LONG-TERM MEASUREMENTS OF RADON PROGENY CONCENTRATIONS WITH SOLID STATE NUCLEAR TRACK DETECTORS

Inhaled radon (²²²Rn) progeny are the most important source of irradiation of the human respiratory tract. Methods for long-term monitoring of the ²²²Rn gas itself are well established, such as through the use of solid-state nuclear track detectors (SSNTDs).However, methods for long-term monitoring of the concentrations of radon progeny, or the equilibrium factor F, are still being actively explored. A brief review of existing methods for long-term measurements of radon progeny concentrations or F with SSNTDs will first be given.In 2004, a method known as the proxy equilibrium factor (F_p) method was proposed to determine F using the bare LR 115 detector. F_p was equal to the ratio between the sum of concentrations of the two alpha emitting radon progeny (²¹⁸Po+²¹⁴Po) to the concentration of ²²²Rn, was found to well correlate with F. The F_p method will be described in details in this chapter. Factors affecting the F_p method such as the removed active layer of the LR 115 detector during chemical etching, presence of ²²⁰Rn in the ambient environment, and deposition of dust particles on the bare LR 115 detector are also discussed. Some applications of the F_p method are then presented, including long-term measurements of radon and thoron concentrations and F in dwellings, passive monitoring of F inside a radon exposure chamber, and derivation of V function for LR115 SSNTDs.