Faster and more accurate transport procedures for HZETRN

Journal Article · Fri Dec 10 00:00:00 EST 2010 · Journal of Computational Physics

DOI:https://doi.org/10.1016/j.jcp.2010.09.010· OSTI ID:21418124

Slaba, T.C., E-mail: [e-mail] ^[1]; Blattnig, S.R., E-mail: [e-mail] ^[1]; Badavi, F.F., E-mail: [e-mail] ^[2]

---

1. NASA Langley Research Center, 2 West Reid St., MS 188E, Hampton, VA 23681 (United States)
2. Christopher Newport University, 1 University Pl., Newport News, VA 23607 (United States)

The deterministic transport code HZETRN was developed for research scientists and design engineers studying the effects of space radiation on astronauts and instrumentation protected by various shielding materials and structures. In this work, several aspects of code verification are examined. First, a detailed derivation of the light particle (A {<=} 4) and heavy ion (A > 4) numerical marching algorithms used in HZETRN is given. References are given for components of the derivation that already exist in the literature, and discussions are given for details that may have been absent in the past. The present paper provides a complete description of the numerical methods currently used in the code and is identified as a key component of the verification process. Next, a new numerical method for light particle transport is presented, and improvements to the heavy ion transport algorithm are discussed. A summary of round-off error is also given, and the impact of this error on previously predicted exposure quantities is shown. Finally, a coupled convergence study is conducted by refining the discretization parameters (step-size and energy grid-size). From this study, it is shown that past efforts in quantifying the numerical error in HZETRN were hindered by single precision calculations and computational resources. It is determined that almost all of the discretization error in HZETRN is caused by the use of discretization parameters that violate a numerical convergence criterion related to charged target fragments below 50 AMeV. Total discretization errors are given for the old and new algorithms to 100 g/cm{sup 2} in aluminum and water, and the improved accuracy of the new numerical methods is demonstrated. Run time comparisons between the old and new algorithms are given for one, two, and three layer slabs of 100 g/cm{sup 2} of aluminum, polyethylene, and water. The new algorithms are found to be almost 100 times faster for solar particle event simulations and almost 10 times faster for galactic cosmic ray simulations.

• OSTI ID: 21418124
• Journal Information: Journal of Computational Physics, Vol. 229, Issue 24; Other Information: DOI: 10.1016/j.jcp.2010.09.010; PII: S0021-9991(10)00504-8; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0021-9991
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
97 MATHEMATICAL METHODS AND COMPUTING
ALGORITHMS
ALUMINIUM
ASTRONAUTS
COMPUTERIZED SIMULATION
CONVERGENCE
COSMIC RADIATION
INTERPLANETARY SPACE
POLYETHYLENES
RADIATION TRANSPORT
SHIELDING MATERIALS
SOLAR PARTICLES
TRANSPORT THEORY
WATER
ELEMENTS
HYDROGEN COMPOUNDS
IONIZING RADIATIONS
MATERIALS
MATHEMATICAL LOGIC
METALS
ORGANIC COMPOUNDS
ORGANIC POLYMERS
OXYGEN COMPOUNDS
PERSONNEL
POLYMERS
POLYOLEFINS
RADIATIONS
SIMULATION
SOLAR RADIATION
SPACE
STELLAR RADIATION