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GCR Environmental Models III: GCR Model Validation and Propagated Uncertainties in Effective DoseThis is the last of three papers focused on quantifying the uncertainty associated with galactic cosmic rays (GCR) models used for space radiation shielding applications. In the first paper, it was found that GCR ions with Z>2 and boundary energy below 500 MeV/nucleon induce less than 5% of the total effective dose behind shielding. This is an important finding since GCR model development and validation have been heavily biased toward Advanced Composition Explorer/Cosmic Ray Isotope Spectrometer measurements below 500 MeV/nucleon. Weights were also developed that quantify the relative contribution of defined GCR energy and charge groups to effective dose behind shielding. In the second paper, it was shown that these weights could be used to efficiently propagate GCR model uncertainties into effective dose behind shielding. In this work, uncertainties are quantified for a few commonly used GCR models. A validation metric is developed that accounts for measurements uncertainty, and the metric is coupled to the fast uncertainty propagation method. For this work, the Badhwar-O'Neill (BON) 2010 and 2011 and the Matthia GCR models are compared to an extensive measurement database. It is shown that BON2011 systematically overestimates heavy ion fluxes in the range 0.5-4 GeV/nucleon. The BON2010 and BON2011 also show moderate and large errors in reproducing past solar activity near the 2000 solar maximum and 2010 solar minimum. It is found that all three models induce relative errors in effective dose in the interval [-20%, 20%] at a 68% confidence level. The BON2010 and Matthia models are found to have similar overall uncertainty estimates and are preferred for space radiation shielding applications.
Document ID
20140006234
Acquisition Source
Langley Research Center
Document Type
Reprint (Version printed in journal)
Authors
Slaba, Tony C.
(NASA Langley Research Center Hampton, VA, United States)
Xu, Xiaojing
(Science Systems and Applications, Inc. Hampton, VA, United States)
Blattnig, Steve R.
(NASA Langley Research Center Hampton, VA, United States)
Norman, Ryan B.
(NASA Langley Research Center Hampton, VA, United States)
Date Acquired
May 27, 2014
Publication Date
April 7, 2014
Publication Information
Publication: Space Weather
Volume: 12
Issue: 4
Subject Category
Space Radiation
Report/Patent Number
NF1676L-17814
Funding Number(s)
WBS: WBS 651549.02.07.10
CONTRACT_GRANT: NNL11AA00B
Distribution Limits
Public
Copyright
Other

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