Radon progeny behavior in diffusion chamber

Abstract

The behavior of short-lived radon progeny in a diffusion chamber was modeled based on the random Brownian motion and diffusion. The modeling enables calculations of the fraction of radon progeny that decays in air, as well as, the distribution of the atoms deposited onto the inner walls of the diffusion chamber. Up to 23% of 218Po decays in air, while 214Pb and 214Bi are almost fully deposited before decaying. The distribution of deposited progeny was found to be non-uniform. In the second part of the paper, deposition of charged progeny atoms was also considered.The influence of non-uniform deposition of radon progeny on the total sensitivity was investigated for an LR 115 detector in one typical diffusion chamber. The electric charge increases the deposition of radon progeny.