A novel method for fitting the electric field inside a hemispherical radon monitor to accurately estimate the collection efficiency of 218Po

The collection efficiency of the hemispherical radon monitors based on electrostatic collection is strongly influenced by the electric field distribution and the relative humidity. Previous studies have been restricted to fitting the electric field using a single-segment, resulting in poor fitting optimality and accuracy. Overestimating or underestimating the fitted value relative to the true value can lead to inaccuracies in estimating the collection efficiency. To address this problem, the aim of this paper is to accurately characterize the electrostatic field of the hemispherical radon monitors using COMSOL software and to fit the potential in a segmented fitting approach. The two-segment fitting method was employed to divide the electric field inside the hemispherical radon monitor into two distinct parts for fitting. The improved fitting model increase the goodness-of-fit by 11.6% over the single-segment fitting model, and improves the accuracy of the collection efficiency of 218Po at different humidity levels. The saturation collection efficiency is also raised, especially when the humidity is greater than 10%, the saturation collection efficiency is increased by 9.2%. Through the improved method, the collection efficiency of 218Po in the hemispherical radon monitor can be accurately estimated and provide technical support for optimizing the electric field of the radon monitor. •The novel method greatly improves the goodness of fit.•The novel method can accurately describe the electric field.•The novel method accurately estimates the collection efficiency of Po-218.•The novel method improves the saturation collection efficiency.