Open AccessInfluence of the superposition approximation on calculated effective dose rates from galactic cosmic rays at aerospace‐related altitudes
Author(s) -
Copeland Kyle
Publication year - 2015
Publication title -
space weather
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.254
H-Index - 56
ISSN - 1542-7390
DOI - 10.1002/2015sw001210
Subject(s) - cosmic ray , superposition principle , physics , monte carlo method , altitude (triangle) , range (aeronautics) , radiation transport , radiation , computational physics , cosmic cancer database , astrophysics , nuclear physics , environmental science , aerospace engineering , statistics , mathematics , quantum mechanics , geometry , engineering
The superposition approximation was commonly employed in atmospheric nuclear transport modeling until recent years and is incorporated into flight dose calculation codes such as CARI‐6 and EPCARD. The useful altitude range for this approximation is investigated using Monte Carlo transport techniques. CARI‐7A simulates atmospheric radiation transport of elements H‐Fe using a database of precalculated galactic cosmic radiation showers calculated with MCNPX 2.7.0 and is employed here to investigate the influence of the superposition approximation on effective dose rates, relative to full nuclear transport of galactic cosmic ray primary ions. Superposition is found to produce results less than 10% different from nuclear transport at current commercial and business aviation altitudes while underestimating dose rates at higher altitudes. The underestimate sometimes exceeds 20% at approximately 23 km and exceeds 40% at 50 km. Thus, programs employing this approximation should not be used to estimate doses or dose rates for high‐altitude portions of the commercial space and near‐space manned flights that are expected to begin soon.