Speaker
Description
The International Space Station (ISS) has provided a wealth of radiation measurements that have directly influenced model development activities and reduced uncertainties. Previous work compared model results from the deterministic radiation transport code, HZETRN, to measurements from active detectors flown on ISS. The active detectors enabled contributions from galactic cosmic rays (GCR) and spatially localized trapped protons to be separated so that observed discrepancies were not obscured by well-known uncertainties with the trapped proton environmental models. In these studies, it was found that the combined model set (i.e. free-space GCR, geomagnetic cutoff, ISS mass shielding distribution, HZETRN) systematically under-estimates measured data, especially at the highest cutoff rigidities. In this presentation, new results from an improved version of HZETRN in which pions are fully coupled to the nucleon and light ion fields are described and evaluated against similar active dosimetry from ISS. It is found that pion-nucleus nuclear interactions contribute significantly to the low energy nucleon field and may account for the systematic errors previously described.
