Pii: S0273-1177(02)00404-0

Deep-space manned flight as a reality depends on a viable solution to the radiation problem. Both acute and chronic radiation health threats are known to exist, with solar particle events as an example of the former and galactic cosmic rays (GCR) of the latter. In this experiment Iron ions of 1A GeV are used to simulate GCR and to determine the secondary radiation field created as the GCR-like particles interact with a thick target. A NASA prepared food pantry locker was subjected to the iron beam and the secondary fiuence recorded. A modified version of the Monte Carlo heavy ion transport code developed by Zeiflin at LBNL is compared with experimental fluence. The foodstuffis modeled as mixed nuts as defined by the 71 ~t edition of the Chemical Rubber Company (CRC) Handbook of Physics and Chemistry. The results indicate a good agreement between the experimental data and the model. The agreement between model and experiment is determined using a linear fit to ordered pairs of data. The intercept is forced to zero. The slope fit is 0.825 and the R 2 value is 0.429 over the resolved fluence region. The removal of an outlier, Z=14, gives values of 0.888 and 0.705 for slope and R 2 respectively. © 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved. I N T R O D U C T I O N The problems of high-energy heavy-ion (HZE) transport in shielding and biological samples are important to the field of space radiation protection. The HZE particles in the galactic cosmic ray (GCR) spectra are responsible for a major portion of the dose equivalent with iron ions having the largest contribution (Ginzburg, 1964; Wilson et a1.,1991; Curtis and Townsend, 1991). Iron ions are therefore a natural choice for the study of GCR on shielding material. Ground-hased experiments with iron beams provide validation for heavy ion transport codes and cross section data for materials of interest. The energy of the iron beam used in this experiment is near the peak of the iron GCR specmun with an experimental value of 1.05 ± 0.005 GeV/nucleon (Zeitlin et al.,1996a). The fragmentation oftbe incident beam is important in the space radiation problem and in the creation of transport models for heavy ions. The emergent secondary field is composed of all elemental ions from the charge of the incident ion down to hydrogen, and neutrons (Curtis and Townsend,1991). This fragmentation of the projectile can occur in both the shield and a biological sample giving rise to a possibly greater dose equivalent behind shielding and in the body (Curtis and Townsend,1991; Townsend et al.,1992). A fragment fluence spectnml is measured to characterize the field. -This fluence spectrum is used to interpret biological results (Curtis et al., 1992) and form an understanding of nuclear transport of ions in various materials. (Townsend et al., 1992). The principle goal of this experiment is to characterize the charge distribution of nuclear fragments produced by high-energy iron nuclei interacting in a NASA pantry locker containing food from the MIR fight test program and to compare these results with Monte Carlo simulations for a similar target.