- Conference date: 24-27 April 2002
- Location: Gatlinburg, Tennessee (USA)
All types of ionizing radiation interact with material by producing atomic or molecular ions, excited states, and secondary electrons. Still, different types of radiation lead to quite different yields of biological damage. It is generally believed that the spatial distributions of ionization and excitation produced by the slowing down of charged particles, particularly electrons, govern the yields of bioactive molecular species. The assessment of these spatial patterns of ionization and excitation depend largely on the production cross sections for secondary electrons, the energies and angular correlations of their production, and the subsequent differential cross sections for their energy loss in the media of interest. The most thorough assessment of spatial patterns of energy deposition by charged particles is obtained using Monte Carlo simulation of charged particle track structure based on the available database of interaction cross sections. This step‐by‐step analysis of the interactions of charged particles, from their initial energies until stopped in the medium, provides detailed information on the spatial distribution of the products of ionization from which subsequent chemical and biochemical reactions can be assessed. Over the years a substantial database has been developed describing the interaction of fast, “bare” charged particles, e.g., electrons, protons, and alpha particles, with atomic and molecular targets. However, as charged particles slow they enter an energy regime where additional energy‐loss channels open and the availability of data is often limited; interest in this region is also intensified because the biological effectiveness of these particles can increase as their energy decreases. This presentation will focus on the special needs for data involving low‐energy electrons and ions, i.e., slowing protons, alpha particles and heavier ions, in a biological environment. A brief discussion of the availability of cross sections will be presented and areas of need for additional data will be discussed.
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