Das Projekt "Biophysicical models for the effectiveness of different radiations" wird vom Umweltbundesamt gefördert und von GSF-Forschungszentrum für Umwelt und Gesundheit, GmbH durchgeführt. Objective: This project involves experimental and theoretical research towards a better understanding of the biological radiation actions of different radiation fields, with particular emphasis on low doses and low dose rates. It aims at an improvement of our present knowledge on somatic and genetic radiation risks of man and to help develop radiation protection instrumentation to measure the characteristic properties with regard to these endpoints in mixed radiation fields. In addition, the combined action of radiation and chemicals (also of those prevalent in the environment) will be investigated on a mechanistic level. General Information: This goal shall be reached by the development of new models based on: the improvement of biophysical track structure calculations for relevant radiation fields (photons, neutrons, electrons, ions) in particular by introducing structured cell geometry, condensed state cross sections, time dependency, and chemical and biological reactions; various codes of other authors will be compared in critical bench mark calculations; the analysis of such physical to chemical to biological track structures will be improved using new cluster algorithms and by testing biophysical models which will be developed; selective radiation biological experiments with soft X-rays and UV-photons will be performed, as well as with alpha-particles and gamma-rays; the biological systems will include appropriate transformational and inactivation assays, etc. The usefulness of a better understanding of radiation effects on members of the public has often been described in the radiation protection literature. This understanding is necessary also to improve the protection of workers and the public in the ALARA-sense of the IRCP, where overestimations of radiation risks might lead, for example, to a not optimum allocation of large resources. Collaboration is foreseen with other projects working on the improvements of dosimeters and on biological radiation effects. Achievements: Objectives of the project include calculation of secondary electrons produced in a water molecule and in a water cluster by proton and electron impact to investigate the influence of physical state on double differential ionization cross sections, testing of the geometry routines simulating a lymphocyte and calculation of single strand breaks (SSB), double strand breaks (DSB) and fields of dicentric chromosomes using simple models of deoxyribonucleic acid (DNA) interaction. A set of calculations of the double and single differential cross sections for secondary electron emission as a function of angle and secondary electron energy have been completed for the case of proton impact on a water molecule and a cluster of water molecules using methods developed for electron impact. ... Prime Contractor: GSF-Forschungszentrum für Umwelt und Gesundheit GmbH; Oberschleissheim; Germany.