Validation of the HZETRN code for laboratory exposures with 1A GeV iron ions in several targets S.A. Walker a , J. Tweed a, * , J.W. Wilson b , F.A. Cucinotta c , R.K. Tripathi b , S. Blattnig b , C. Zeitlin d , L. Heilbronn d , J. Miller d a Department of Mathematics and Statistics, Old Dominion University, Hampton Bvld, Norfolk, VA 23529, USA b NASA Langley Research Center, Hampton, VA 23681-2199, USA c NASA Johnson Space Center, Houston, TX 77058, USA d Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA Received 24 July 2004; received in revised form 24 February 2005; accepted 28 February 2005 Abstract A new version of the HZETRN code capable of validation with HZE ions in either the laboratory or the space environment is under development. The computational model consists of the lowest order asymptotic approximation followed by a Neumann series expansion with non-perturbative corrections. The physical description includes energy loss with straggling, nuclear attenuation, nuclear fragmentation with energy dispersion and downshift. Measurements to test the model were performed at the Alternating Gradient Synchrotron and the NASA Space Radiation Laboratory at Brookhaven National Laboratory with iron ions. Surviving beam particles and produced fragments were measured with solid-state detectors. Beam analysis software has been written to relate the computational results to the measured energy loss spectra of the incident ions for rapid validation of modeled target transmis- sion functions. Ó 2005 COSPAR. Published by Elsevier Ltd. All rights reserved. Keywords: Ion transport; High charge and energy ions; BoltzmannÕs equation; GreenÕs function 1. Introduction During a space mission, spacecraft are exposed to radiations of various types over a broad energy spec- trum depending on location in space and time. Among the more important of these are heavy-ion cosmic radi- ations that originate from the sun and galactic sources. The shielding and exposure of crewmembers are con- trolled by the transport properties of these radiations through the spacecraft, its onboard systems and the bodies of the individuals themselves. Transport codes therefore play an important role in estimating and man- aging the radiation risk to the astronauts and their equipment. One way of reducing the radiation dose experienced is by the addition of shielding at those places within the spacecraft where large amounts of time are spent. In consequence, there is considerable interest in the development of new shielding materials. Since, it is clearly impractical to verify the shielding properties of every candidate material and configuration in space, shield designers rely heavily upon models of radiation transport and measurements taken at particle accelera- tors, which play an important role in the model design and validation process. Numerical solution methods for the Boltzmann trans- port equation are best suited to space radiations where the energy spectra are smooth over large energy intervals and less suited to the simulation of laboratory beams which exhibit large spectral variation over a very limited energy domain and large energy derivative. As a result, codes for space based on these numerical methods are 0273-1177/$30 Ó 2005 COSPAR. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.asr.2005.02.077 * Corresponding author. Tel.: +1 757 683 3909; fax: +1 757 683 3885. E-mail address: jtweed@odu.edu (J. Tweed). www.elsevier.com/locate/asr Advances in Space Research 35 (2005) 202–207