Particle size distribution of 7Be-aerosols formed in high energy accelerator tunnels

The 7Be, produced by nuclear spallation reactions in the air of high energy accelerator tunnels, is present in the form of an aerosol. The size distribution of the 7Be-aerosols was measured with a parallel plate diffusion battery and was found to be a log-normal distribution with a geometric mean radii of 27 nm and a logarithmic standard deviation of 0.36. The formation of the 7Be-aerosol is adequately explained by the attachment of 7Be to non-radioactive aerosols containing sulfates, which are produced by radiation induced oxidation reactions of SO2 present in the air. (author)