| 1. |
- El-Jaby, S., et al.
(author)
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ISSCREM: International Space Station cosmic radiation exposure model
- 2013
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In: IEEE Aerospace Conference Proceedings. - 1095-323X. - 9781467318112
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Conference paper (peer-reviewed)abstract
- A semi-empirical model is derived from operational data collected aboard the International Space Station (ISS) with the U.S. tissue equivalent proportional counter (TEPC). The model provides daily and cumulative mission predictions of the operational dose equivalent that space-crew may receive from galactic cosmic radiation (GCR) and trapped radiation (TR) sources as a function of the ISS orbit. The parametric model for GCR exposure correlates the TEPC dose equivalent rate to the cutoff rigidity at ISS altitudes while the TR parametric model relates this quantity to the mean atmospheric density at the crossing of the South Atlantic Anomaly (SAA). The influences of solar activity, flux asymmetry inside the SAA, detector orientation, and position aboard the ISS on the dose equivalent have been examined. The model has been successfully benchmarked against measured data for GCR and TR exposures to within ±10% and ±20%, respectively, over periods of time ranging from a single day to a full mission. In addition, preliminary estimates of the protection quantity of effective dose equivalent have been simulated using the PHITS Monte Carlo transport code. These simulations indicate that the TEPC dose equivalent is a conservative estimate of the effective dose equivalent.
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| 2. |
- El-Jaby, S., et al.
(author)
-
Method for the prediction of the effective dose equivalent to the crew of the International Space Station
- 2014
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 53:5, s. 810-817
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Journal article (peer-reviewed)abstract
- This paper describes a methodology for assessing the pre-mission exposure of space crew aboard the International Space Station (ISS) in terms of an effective dose equivalent. In this approach, the PHITS Monte Carlo code was used to assess the particle transport of galactic cosmic radiation (GCR) and trapped radiation for solar maximum and minimum conditions through an aluminum shield thickness. From these predicted spectra, and using fluence-to-dose conversion factors, a scaling ratio of the effective dose equivalent rate to the ICRU ambient dose equivalent rate at a 10 mm depth was determined. Only contributions from secondary neutrons, protons, and alpha particles were considered in this analysis. Measurements made with a tissue equivalent proportional counter (TEPC) located at Service Module panel 327, as captured through a semi-empirical correlation in the ISSCREM code, where then scaled using this conversion factor for prediction of the effective dose equivalent. This analysis shows that at this location within the service module, the total effective dose equivalent is 10-30% less than the total TEPC dose equivalent. Approximately 75-85% of the effective dose equivalent is derived from the OCR. This methodology provides an opportunity for pre-flight predictions of the effective dose equivalent and therefore offers a means to assess the health risks of radiation exposure on ISS flight crew. Crown copyright (C) 2014 Published by Elsevier Ltd. on behalf of COSPAR. All rights reserved.
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