A theoretical investigation in the Lucas cell

A Lucas cell is a scintillation chamber for the detection of radon. Its efficiency and energy spectrum can be described by a theoretical model of the detection process in the cell volume. The numerical investigation presented here yields spatial distributions of the detection probability (efficiency) and of the α-particle's energy deposited in the scintillator. Both quantities are considered for radon and two α-emitting daughter nuclides. Moreover theoretical energy spectra are given and compared with measured data. Finally the detector's efficiency is considered theoretically under varying discriminator settings. The results presented in this paper lead to a consistent explanation of a Lucas cell's performance. In addition, the theoretical model can serve for a computer aided cell design. It enables the designer to find a suitable geometry in order to achieve a desired efficiency. (orig.)