Exposure to small doses of radiation occupies a relatively wide area in daily radiation protection practice. Dose-effect relationships in the low-dose range are still largely based on extrapolations from the high-dose range with all the resulting uncertainties. In order to quantify the biological consequences of low doses more precisely, a detailed understanding of the radiation effect mechanism is required, especially in the low dose range and at small dose rates. The physical phase of the radiation effect is characterized by the fact that the energy of all types of radiation is transferred to the biological tissue quite predominantly by ionizations, with about half of these ionizations occurring by secondary electrons with an energy of less than 1 keV. A large number of such low-energy electrons are also released, for example, during the decay of so-called Auger electron emitters. For the understanding of radiobiological mechanisms of action, the investigation of the mechanism of action, also known as the Auger effect, is particularly useful.

The scientific focus in S-US is on the investigation of the biological effect of low-energy electrons and the impact of the dose rate effect on the biological radiation effect, as well as the development of new indicators based on characteristic changes in gene and protein expression, which are suitable for retrospectively estimating the level of accidental radiation exposure reliably and quickly.