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Comparisons of Integrated Radiation Transport Models with Microdosimetry Data in SpaceflightAstronauts are exposed to galactic cosmic rays (GCR), trapped protons, and possible solar particle events (SPE) during spaceflight. For such complicated mixtures of radiation types and kinetic energies, tissue equivalent proportional counters (TEPC's) represent a simple time-dependent approach for radiation monitoring. Of interest in radiation protection is the average quality factor of a radiation field defined as a function of linear energy transfer, LET, Q(sub ave)(LET). However TEPC's measure the average quality factors as a function of lineal energy (y), Q(sub ave)(y) defined as the average energy deposition in a volume divided by the average chord length of the volume. Lineal energy, y deviates from LET due to energy straggling, delta-ray escape or entry, and nuclear fragments produced in the detector. Using integrated space radiation models that includes the transport code HZETRN/BRYNTRN, the quantum nuclear interaction model, QMSFRG, and results from Monte-Carlo track simulations of TEPC's response to ions, we consider comparisons of model calculations to TEPC results from NASA missions in low Earth orbit and make predictions for lunar and Mars missions. Good agreement between the model and measured spectra from past NASA missions is found. A finding of this work is that TEPC's values for trapped or solar protons of Q(sub ave)(y) range from 1.9-2.5, overestimating Q(sub ave)(LET), which ranges from 1.4-1.6 with both quantities increasing with shielding depth due to nuclear secondaries Comparisons for the complete GCR spectra show that Q(sub ave)(LET) for GCR is approximately 3.5-4.5, while TEPC's measure 2.9-3.4 for Q(sub ave)(y) with the GCR values decreasing with depth as heavy ions are absorbed in shielding material. Our results support the use of TEPC's for space radiation environmental monitoring when computational analysis is used for proper data interpretation.
Document ID
20080026341
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Cucinotta, Francis A.
(NASA Johnson Space Center Houston, TX, United States)
Nikjoo, H.
(NASA Johnson Space Center Houston, TX, United States)
Kim, M. Y.
(NASA Johnson Space Center Houston, TX, United States)
Hu, X.
(NASA Johnson Space Center Houston, TX, United States)
Dicello, J. F.
(Johns Hopkins Medical Institutions Baltimore, MD, United States)
Pisacane, V. L.
(Naval Academy Annapolis, MD, United States)
Date Acquired
August 24, 2013
Publication Date
June 12, 2006
Subject Category
Space Radiation
Meeting Information
Meeting: Tenth Symposium on Neutron Dosimety
Location: Uppsala
Country: Sweden
Start Date: June 12, 2006
End Date: June 16, 2006
Distribution Limits
Public
Copyright
Other

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