Track structure and radiation transport model for space radiobiology studies

Abstract

Radiobiology experiments performed in space are deemed necessary for validation of risk-assessment methods. The understanding of space radiobiology experiments must combine knowledge of the space radiation environment, radiation transport, and models of biological response. The heavy ion transport code HZETRN has recently been combined with improved models of the galactic cosmic rays (GCR) and extensive comparisons made to measurements on the space shuttle with a tissue equivalent, proportional counter. HZETRN was also coupled with track-structure models of biological damage from heavy ions. Track-structure calculations using improved models of the radial dose distribution around the path of heavy ions provide a good description of ground-based experiments for inactivation cross sections. Therefore, we use these models to predict inactivation of Bacillus Subtilis spores in space. Calculations consider single-particle effects, as well as the background from low linear energy transfer ions of the GCR and trapped radiations on the radial distributions of effects measured in plastic detectors.