The health risk of exposure to Radon/Thoron daughters and radioactive aerosols is influenced by activity-size distribution of the carrying particles. Therefore, to enable practical measurements of the activity-size distribution under field conditions, SARAD has developed this portable measurement system in collaboration with the University of Göttingen

This system consists of:

• six (up to eight) low pressure separation stages with in-situ alpha spectroscopy,
• removable diffusion battery for unattached radon daughters (alternatively mesh grid with in-situ detection of this fraction),
• backup filter with in-situ spectroscopy,
• automatic control and analysis system.

The low-pressure cascade impactor allows to determine the activity-size distribution over a very wide range, from few nanometers to several micrometers equivalent particle diameter.