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- Grindborg, J.-E., et al.
(author)
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Nanodosimetric measurements and calculations in a neutron therapy beam
- 2007
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In: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 126:1-4, s. 463-466
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Journal article (peer-reviewed)abstract
- A comparison of calculated and measured values of the dose mean lineal energy (yD) for the former neutron therapy beam at Louvain-la-Neuve is reported. The measurements were made with wall-less tissue-equivalent proportional counters using the variance-covariance method and simulating spheres with diameters between 10 nm and 15 µm. The calculated yD-values were obtained from simulated energy distributions of neutrons and charged particles inside an A-150 phantom and from published yD-values for mono-energetic ions. The energy distributions of charged particles up to oxygen were determined with the SHIELD-HIT code using an MCNPX simulated neutron spectrum as an input. The mono-energetic ion yD-values in the range 3-100 nm were taken from track-structure simulations in water vapour done with PITS/KURBUC. The large influence on the dose mean lineal energy from the light ion (A > 4) absorbed dose fraction, may explain an observed difference between experiment and calculation. The latter being larger than earlier reported result. Below 50 nm, the experimental values increase while the calculated decrease. © The Author 2007. Published by Oxford University Press. All rights reserved.
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| 5. |
- Ersmark, T., et al.
(author)
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Influence of geometry model approximations on Geant4 simulation results of the Columbus/ISS radiation environment
- 2007
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In: Radiation Measurements. - : Elsevier BV. - 1350-4487 .- 1879-0925. ; 42, s. 1342-1350
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Journal article (peer-reviewed)abstract
- The influence of geometry model approximations on Geant4 Monte Carlo simulation results of the radiation environment on-board the Columbus module of the International Space Station (ISS) has been investigated. Three geometry models of Columbus with different levels of detail and a geometry model of ISS have been developed. These geometries have been used for Geant4 simulations of the radiation environment inside Columbus induced by trapped protons and Galactic Cosmic Ray protons. Simulated dose rates and particle spectra on-board Columbus for each of the three Columbus models, with or without the ISS geometry model included, are presented and compared. From comparisons of simulated dose rates and particle spectra for the three different geometry models it was found that the most detailed geometry model (750 volumes) produced results similar to a much less detailed model (23 volumes). The most detailed geometry model was concluded to be a sufficiently detailed approximation of the physical Columbus for the purpose of proton induced space radiation studies. The simulated dose rates are compatible with measurements on-board the ISS. The simulation results also show that an increase in shielding thickness decreases the simulated dose rate induced by trapped protons. For Galactic Cosmic Ray protons the dose rate remains unchanged or is slightly increased.
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| 6. |
- Ersmark, Tore, et al.
(author)
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Status of the DESIRE project : Geant4 physics validation studies and first results from columbus/ISS radiation simulations
- 2004
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In: IEEE NUCLEAR SCIENCE SYMPOSIUM, CONFERENCE RECORD. ; , s. 1540-1544
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Conference paper (other academic/artistic)abstract
- The DESIRE (Dose Estimation by Simulation of the ISS Radiation Environment) project aimes to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Firstly physics benchmark studies have been performed and comparisons made to experimental data and other particle transport programs. This will be followed by a detailed evaluation of the incident radiation fields on the ISS and culminate with the geometry modelling and full-scale flux and dose simulations for the Columbus. Geant4 validation studies are presented here. These concern the angle and energy distribution of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data and other particle transport programs. Geant4 using the "Binary Cascade" model for inelastic nucleon reactions performs very well in these comparisons but some issues with other models remain to be resolved if these models are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of relevant radiation field components through the hull of the Columbus/ISS are also presented.
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| 7. |
- Ersmark, Tore, et al.
(author)
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Status of the DESIRE project : Geant4 physics validation studies and first results from columbus/ISS radiation simulations
- 2004
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In: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 51:4, s. 1378-1384
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Journal article (peer-reviewed)abstract
- The Dose Estimation by Simulation of the ISS Radiation Environment (DESIRE) project aims to accurately calculate radiation fluxes and doses to astronauts inside the European Columbus module of the International Space Station using Geant4. Since Geant4 has not been previously used for this type of application it needs to be validated. This will be followed by a detailed evaluation of the incident radiation fields on ISS and culminate with the geometry modeling and full-scale flux and dose simulations for Columbus. Geant4 validation studies and comparisons to other tools are presented. These concern the angle and energy distributions of particles leaving irradiated targets and of energy depositions in the targets. Comparisons are made between simulations using different Geant4 physics models, experimental data, and other particle transport programs. Geant4 using the Binary Cascade model for inelastic nucleon reactions performs very well in these comparisons, but some issues with other models remain to be resolved if they are to be used for space radiation shielding applications. Results of Geant4 simulations of the transport of some relevant radiation field components through the hull of a simplified model of Columbus are also presented.
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