| 1. |
- Bertucci, Antonella, et al.
(author)
-
Shielding of relativistic protons
- 2007
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In: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 46:2, s. 107-111
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Journal article (peer-reviewed)abstract
- Protons are the most abundant element in the galactic cosmic radiation, and the energy spectrum peaks around 1 GeV. Shielding of relativistic protons is therefore a key problem in the radiation protection strategy of crewmembers involved in long-term missions in deep space. Hydrogen ions were accelerated up to 1 GeV at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, New York. The proton beam was also shielded with thick ( about 20 g/cm(2)) blocks of lucite (PMMA) or aluminium ( Al). We found that the dose rate was increased 40-60% by the shielding and decreased as a function of the distance along the axis. Simulations using the General Purpose Particle and Heavy-Ion Transport code System (PHITS) show that the dose increase is mostly caused by secondary protons emitted by the target. The modified radiation Weld after the shield has been characterized for its biological eVectiveness by measuring chromosomal aberrations in human peripheral blood lymphocytes exposed just behind the shield block, or to the direct beam, in the dose range 0.53 Gy. Notwithstanding the increased dose per incident proton, the fraction of aberrant cells at the same dose in the sample position was not significantly modified by the shield. The PHITS code simulations show that, albeit secondary protons are slower than incident nuclei, the LET spectrum is still contained in the low-LET range (
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| 2. |
- Casolino, M., et al.
(author)
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The altcriss project on board the International Space Station
- 2007
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 40:11, s. 1746-1753
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Journal article (peer-reviewed)abstract
- The Alteriss project aims to perform a long term survey of the radiation environment on board the International Space Station. Measurements are being performed with active and passive devices in different locations and orientations of the Russian segment of the station. The goal is to perform a detailed evaluation of the differences in particle fluence and nuclear composition due to different shielding material and attitude of the station. The Sileye-3/Alteino detector is used to identify nuclei up to Iron in the energy range above similar or equal to 60 MeV/n. Several passive dosimeters (TLDs, CR39) are also placed in the same location of Sileye-3 detector. Polyethylene shielding is periodically interposed in front of the detectors to evaluate the effectiveness of shielding on the nuclear component of the cosmic radiation. The project was submitted to ESA in reply to the AO in the Life and Physical Science of 2004 and data taking began in December 2005. Dosimeters and data cards are rotated every 6 months: up to now three launches of dosimeters and data cards have been performed and have been returned with the end of expedition 12 and 13. (C) 2007 Published by Elsevier Ltd on behalf of COSPAR.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- La Tessa, Chiara, 1979, et al.
(author)
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Fragmentation of 1 GeV/nucleon iron ions in thick targets relevant for space exploration
- 2005
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 35:2, s. 223-229
-
Journal article (peer-reviewed)abstract
- We have measured charged nuclear fragments produced by 1 GeV/nucleon 56 Fe ions interacting with aluminium, polyethylene and lead. These materials are relevant for assessment of radiation risk for manned space flight. The data will be presented in a form suitable for comparison with models of nuclear fragmentation and transport, including linear energy transfer (LET) spectrum, fluence for iron and fragments, event-tack- and even t-dose-averaged LET, total dose and iron contribution to dose.
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| 7. |
- La Tessa, Chiara, 1979, et al.
(author)
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Test of weak and strong factorization in nucleus-nucleus collisions at several hundred MeV/nucleon
- 2007
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In: Nuclear Physics A. - : Elsevier BV. - 0375-9474. ; 791:3-4, s. 434-450
-
Journal article (peer-reviewed)abstract
- Projectile total and partial charge-changing cross sections have been measured for argon ions at 400 MeV/nucleon in carbon, aluminum, copper, tin and lead targets; cross sections for hydrogen were also obtained using a polyethylene target. The validity of weak and strong factorization properties has been investigated for partial charge-changing cross sections; measurements obtained for carbon, neon and silicon beams at 290 and 400 MeV/nucleon and iron beam at 400 MeV/nucleon, in carbon, aluminum, copper, tin and lead targets have also been used for the test. Two different analysis methods were applied and both indicated that these properties are valid, without any significant difference between weak and strong factorization. The factorization parameters have then been calculated and analyzed in order to find some systematic behavior useful for modeling purposes. (C) 2007 Elsevier B.V. All rights reserved.
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| 8. |
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| 9. |
- Mancusi, Davide, 1980, et al.
(author)
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Calculation of Energy-Deposition Distributions and Microdosimetric Estimation of the Biological Effect of a 9C Beam
- 2009
-
In: Radiation and Environmental Biophysics. - 1432-2099 .- 0301-634X. ; 48:2, s. 135-143
-
Journal article (peer-reviewed)abstract
- Among the alternative beams being recently considered for external cancer radiotherapy, C-9 has received some attention because it is expected that its biological effectiveness could be boosted by the beta-delayed emission of two alpha particles and a proton that takes place at the ion-stopping site. Experiments have been performed to characterise this exotic beam physically and models have been developed to estimate quantitatively its biological effect. Here, the particle and heavy-ion transport code system (PHITS ) is used to calculate energy-deposition and linear energy transfer distributions for a C-9 beam in water and the results are compared with published data. Although PHITS fails to reproduce some of the features of the distributions, it suggests that the decay of C-9 contributes negligibly to the energy-deposition distributions, thus contradicting the previous interpretation of the measured data. We have also performed a microdosimetric calculation to estimate the biological effect of the decay, which was found to be negligible; previous microdosimetric Monte-Carlo calculations were found to be incorrect. An analytical argument, of geometrical nature, confirms this conclusion and gives a theoretical upper bound on the additional biological effectiveness of the decay. However, no explanation can be offered at present for the observed difference in the biological effectiveness between C-9 and C-12; the reproducibility of this surprising result will be verified in coming experiments.
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| 10. |
- Mancusi, Davide, 1980, et al.
(author)
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Comparison of aluminum and lucite for shielding against 1 GeV protons
- 2007
-
In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 40:4, s. 581-585
-
Journal article (peer-reviewed)abstract
- Shielding is the only countermeasure currently available for exposure to cosmic radiation during space travel. We compared aluminum (Al) and polymethylmethacrylate (PMMA, or lucite) shields of 20 g/cm^2 thickness using 1 GeV protons accelerated at the NASA Space Radiation Laboratory. The dose rate increased after the shield, and the increase was more pronounced after the Al than the PMMA shield. No significant differences in the induction of chromosomal aberrations were observed in human lymphocytes exposed to the same dose with no shield or behind the Al and PMMA blocks. However, the biological effectiveness per incident proton was increased by the shields. Simulations using the General-Purpose Particle and Heavy-Ion Transport Code System (PHITS) show that the increase in dose is caused by target fragments, and aluminum produces more secondary protons than PMMA. Nevertheless, the spectrum of particles behind the shield is confined within the low-LET region, and the biological effectiveness is consequently similar.
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| 11. |
- Mancusi, Davide, 1980, et al.
(author)
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PHITS - benchmark of partial charge-changing cross sections for intermediate-mass systems
- 2007
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In: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 254:1, s. 30-38
-
Journal article (peer-reviewed)abstract
- The PHITS (Particle and Heavy Ion Transport System) code is a three-dimensional Monte Carlo code that is able to simulate the transport of nuclei and other particles in complicated geometries and calculate fluxes, doses, energy-deposition distributions and many other observables. Among its many possible fields of application, it can be used e.g. to design and optimise radiation shields for space vessels. However, the reliability of the predictions of the code depends directly on the certified accuracy of the code components, i.e. the models the code uses to estimate the quantities necessary for the transport calculation. As a part of a comprehensive benchmarking program, we have investigated the possibility of using PHITS to calculate partial charge-changing cross sections and we have compared the results with measurements performed by some of us (CZ, LH, JM, SG). The results, although limited, suggest that the current reaction-cross-section models might be inadequate for use in space radioprotection; we therefore claim the need for a thorough benchmarking of the models and for new reaction-cross-section measurements and experimental techniques.
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| 12. |
- Mancusi, Davide, 1980, et al.
(author)
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Stability of Nuclei in Peripheral Collisions in the JAERI Quantum Molecular Dynamics Model
- 2009
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In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 79:1
-
Journal article (peer-reviewed)abstract
- The JAERI quantum molecular dynamics (JQMD) model has been successfully used for a long time now to describe many different aspects of nuclear reactions in a unified way. In some cases, however, the JQMD model cannot produce consistent results: First, it lacks a fully relativistically covariant approach to the problem of molecular dynamics; second, the quantum-mechanical ground state of nuclei cannot be faithfully reproduced in a semiclassical framework. Therefore, we introduce R-JQMD, an improved version of JQMD that also features a new ground-state initialization algorithm for nuclei. We compare the structure of the two codes and discuss whether R-JQMD can be adjusted to improve JQMD's agreement with measured heavy-ion fragmentation cross sections.
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| 13. |
- Matthia, D., et al.
(author)
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Temporal and spatial evolution of the solar energetic particle event on 20 January 2005 and resulting radiation doses in aviation
- 2009
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 114:8, s. A08104 (art no)-
-
Journal article (peer-reviewed)abstract
- The solar energetic particle event on 20 January 2005 was one of the largest ground level events ever observed. Neutron monitor stations in the Antarctic recorded count rate increases of several thousand percent caused by secondary energetic particles, and it took more than 36 h to return to background level. Such huge increases in high energetic solar cosmic radiation on the ground are obviously accompanied by considerable changes in the radiation environment at aviation altitudes. Measurements of 28 neutron monitor stations were used in this work to numerically approximate the primary solar proton spectra during the first 12 h of the event by minimizing the differences between measurements and the results of Monte-Carlo calculated count rate increases. The primary spectrum of solar energetic protons was approximated by a power law in rigidity and a linear angular distribution. The incoming direction of the solar energetic particles was determined and compared to the interplanetary magnetic field direction during the event. The effects on the radiation exposure at altitudes of about 12 km during that time were estimated to range from none at low latitudes up to almost 2 mSv/h for a very short time in the Antarctic region and about 0.1 mSv/h at high latitudes on the Northern Hemisphere. After 12 h, dose rates were still increased by 50% at latitudes above 60 degrees whereas no increases at all occurred at latitudes below 40 degrees during the whole event.
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| 14. |
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| 15. |
- Matthiä, Daniel, et al.
(author)
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The Ground Level Event 70 on December 13th, 2006 and Related Effective Doses at Aviation Altitudes
- 2009
-
In: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 136:4, s. 304-310
-
Journal article (peer-reviewed)abstract
- The 70th ground level event in the records of the Neutron Monitor network occurred on 13 December 2006 reaching a maximum count rate increase at the Oulu station of more than 90% during the 5 min interval 3.05-3.10 UTC. Thereafter, count rates gradually decreased registering increases of a few per cent above the galactic cosmic ray background after a few hours. The primary proton spectrum during the first 6 h after the onset of the event is characterised in this work by fitting the energy and angular distribution by a power law in rigidity and a linear dependence in the pitch angle using a minimisation technique. The results were obtained by analysing the data from 28 Neutron Monitor stations. At very high northern and southern latitudes, the effective dose rates were estimated to reach values of 25-30 mu Sv h(-1) at atmospheric depth of 200 g cm(-2) during the maximum of the event. The increase in effective dose during north atlantic and polar flights was estimated to be in the order of 20 %.
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| 16. |
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| 17. |
- Ota, S., et al.
(author)
-
Neutron Production in the Lunar Subsurface from Galactic Cosmic Rays
- 2009
-
In: IEEE Aerospace Conference Proceedings. - 1095-323X. - 9781424438877
-
Conference paper (peer-reviewed)abstract
- The neutron production from galactic cosmic ray (GCR) protons and alpha particles in the lunar subsurface was estimated using the three-dimensional Monte Carlo simulation code PHITS. The PHITS simulations of equilibrium neutron density profiles in the lunar subsurface were compared with experimental data by the Apollo 17 Lunar Neutron Probe Experiment. By use of the latest GCR spectra based on BESS measurements and well-benchmarked nuclear interaction models, our calculations well reproduced the data within the experimental error of 15% (measurement) + 30% (systematic) at the region shallower than 300 g/cm2. However, our calculation showed 10-20% higher values in the deeper region.
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| 18. |
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| 19. |
- Sato, T., et al.
(author)
-
Biological Dose Estimation for Charged-Particle Therapy using an Improved PHITS Code Coupled with a Microdosimetric Kinetic Model
- 2009
-
In: Radiation Research. - 1938-5404 .- 0033-7587. ; 171:1, s. 107-117
-
Journal article (peer-reviewed)abstract
- Microdosimetric quantities such as lineal energy, y, are better indexes for expressing the RBE of HZE particles in comparison to LET. However, the use of microdosimetric quantities in computational dosimetry is severely limited because of the difficulty in calculating their probability densities in macroscopic matter. We therefore improved the particle transport simulation code PHITS, providing it with the capability of estimating the microdosimetric probability densities in a macroscopic framework by incorporating a mathematical function that can instantaneously calculate the probability densities around the trajectory of HZE particles with a precision equivalent to that of a microscopic track-structure simulation. A new method for estimating biological dose, the product of physical dose and RBE, from charged-particle therapy was established using the improved PHITS coupled with a microdosimetric kinetic model. The accuracy of the biological dose estimated by this method was tested by comparing the calculated physical doses and RBE values with the corresponding data measured in a slab phantom irradiated with several kinds of HZE particles. The simulation technique established in this study will help to optimize the treatment planning of charged-particle therapy, thereby maximizing the therapeutic effect on tumors while minimizing unintended harmful effects on surrounding normal tissues.
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| 20. |
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| 21. |
- Sato, T., et al.
(author)
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PARMA: PHITS-based analytical radiation model in the atmosphere - Verification of its accuracy in estimating cosmic radiation doses
- 2008
-
In: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. - 9780735405592 ; 1034, s. 99-102
-
Conference paper (peer-reviewed)abstract
- Estimation of cosmic-ray spectra in the atmosphere has been an essential issue in the evaluation of the aircrew doses. We therefore developed an analytical model that can predict the terrestrial neutron, proton, He nucleus, muon, electron, positron and photon spectra at altitudes below 20 km, based on the Monte Carlo simulation results of cosmic-ray propagation in the atmosphere performed by the PHITS code. The model was designated PARMA. In order to examine the accuracy of PARMA in terms of the neutron dose estimation, we measured the neutron dose rates at the altitudes between 20 to 10400 m, using our developed dose monitor DARWIN mounted on an aircraft. Excellent agreement was observed between the measured dose rates and the corresponding data calculated by PARMA coupled with the fluence-to-dose conversion coefficients, indicating the applicability of the model to be utilized in the route-dose calculation.
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| 22. |
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| 23. |
- Sato, T., et al.
(author)
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Simulations of an Accelerator-Based Shielding Experiment Using the Particle and Heavy-Ion Transport code System PHITS
- 2005
-
In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 35:2, s. 208-213
-
Journal article (peer-reviewed)abstract
- In order to estimate the biological effects of HZE particles, an accurate knowledge of the physics of interaction of HZE particles is necessary. Since the heavy ion transport problem is a complex one, there is a need for both experimental and theoretical studies to develop accurate transport models. RIST and JAERI (Japan), GSI (Germany) and Chalmers (Sweden) are therefore currently developing and bench marking the General-Purpose Particle and Heavy-Ion Transport code System (PHITS), which is based on the NMTC and MCNP for nucleon/meson and neutron transport respectively, and the JAM hadron cascade model. PHITS uses JAERI Quantum Molecular Dynamics (JQMD) and the Generalized Evaporation Model (GEM) for calculations of fission and evaporation processes, a model developed at NASA Langley for calculation of total reaction cross sections, and the SPAR model for stopping power calculations. The future development of PHITS includes better parameterization in the JQMD model used for the nucleus-nucleus reactions, and improvement of the models used for calculating total reaction cross sections, and addition of routines for calculating elastic scattering of heavy ions, and inclusion of radioactivity and burn up processes. As a part of an extensive bench marking of PHITS, we have compared energy spectra of secondary neutrons created by reactions of HZE particles with different targets, with thicknesses ranging from
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| 24. |
- Sihver, Lembit, 1962, et al.
(author)
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Bench marking of calculated projectile fragmentation cross sections using the 3-D, MC codes PHITS, FLUKA, HETC-HEDS, MCNPX_HI, and NUCFRG2
- 2008
-
In: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 63:7-10, s. 865-877
-
Journal article (peer-reviewed)abstract
- Particles and heavy ions are used in various fields of nuclear physics, medical physics, and material science, and their interactions with different media, including human tissue and critical organs, have therefore carefully been investigated both experimentally and theoretically since the 1930s. However, heavy-ion transport includes many complex processes and measurements for all possible systems, including critical organs, would be impractical or too expensive e.g. direct measurements of dose equivalents to critical organs in humans cannot be performed. A reliable and accurate particle and heavy-ion transport code is therefore an essential tool in the design study of accelerator facilities as well as for other various applications. Recently, new applications have also arisen within transmutation and reactor science, space and medicine, especially radiotherapy, and several accelerator facilities are operating or planned for construction. Accurate knowledge of the physics of interaction of particles and heavy ions is also necessary for estimating radiation damage to equipment used on space vehicles, to calculate the transport of the heavy ions in the galactic cosmic ray (GCR) through the interstellar medium, and the evolution of the heavier elements after the Big Bang. Concerns about the biological effect of space radiation and space dosimetry are increasing rapidly due to the perspective of long-duration astronaut missions, both in relation to the International Space Station and to manned interplanetary missions in near future. Radiation protection studies for crews of international flights at high altitude have also received considerable attention in recent years. There is therefore a need to develop accurate and reliable particle and heavy-ion transport codes. To be able to calculate complex geometries, including production and transport of protons, neutrons, and alpha particles, 3-dimensional transport using Monte Carlo (MC) technique must be used. Today several particle and heavy-ion MC transport codes exist, e.g. Particle and Heavy-Ion Transport code System (PHITS), High Energy Transport Code-Human Exploration and Development of Space (HETC-HEDS). SHIELD-HIT, GEANT4, FLUKA. MARS. and MCNPX. In this paper, we present an extensive benchmarking of the calculated projectile fragmentation cross-sections from the reactions of 300-1000MeV/u Si-28, Ar-40, and Fe-56 on polyethylene, carbon. aluminum. and copper targets (relevant to space radioprotection) using PHITS, FLUKA, HETC-HEDS, and MCNPX, against measurements. The influence of the different models used in the different transport codes on the calculated results is also discussed. Some measured cross-sections are also compared to the calculated cross-sections using NUCFRG2, which are incorporated in the 1-dimensional, deterministic radiation transport code HZETRN.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Sihver, Lembit, 1962, et al.
(author)
-
Improved dose and fluence calculations by using tabulated cross sections in PHITS
- 2008
-
In: IEEE Nuclear Science Symposium Conference Record. - 1095-7863. - 9781424427154 ; , s. 4983-4985
-
Conference paper (peer-reviewed)abstract
- In this paper we present a new method to increase the accuracy of the calculated fragmentation yields for light fragments when using the particle and heavy ion Monte Carlo transport code PHITS. The method consists in biasing the event generator without giving up fundamental conservation laws within each event; in particular, the possibility for the user to specify tables of projectile-fragmentation cross sections for heavy ions is introduced. The cross-section tables are used to determine a priori what reaction channel should be chosen. With this method PHITS can combine its event generators for nuclear reactions with external models or measured values to correct the cross sections which are not calculated with the required accuracy by default The method is based on the possibility to identify the projectile-like "leading" fragment, i.e. the one with the highest charge. If the fragment can be produced with multiplicity higher than one, our procedure cannot reproduce the user-supplied fragmentation cross section.
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| 29. |
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| 30. |
- Sihver, Lembit, 1962, et al.
(author)
-
Present status and validation of HIBRAC
- 2009
-
In: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 44:1, s. 38-46
-
Journal article (peer-reviewed)abstract
- This paper describes in detail the latest version of HIBRAC, a computer code to calculate one-dimensional deterministic particle transport, designed for application in treatment-planning systems when using highly energetic ions for radiotherapy. HIBRAC can calculate dose, dose-average LET (Linear Energy Transfer), track-average LET, fluence and energy distributions as a function of the penetration depth of light ion beams in any solid and fluid target material. The validity of the code is verified against measured dose and fluence distributions. The code shows good agreement for all the systems studied. (C) 2008 Elsevier Ltd. All rights reserved.
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| 31. |
- Sihver, Lembit, 1962, et al.
(author)
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Recent developments and benchmarking of the PHITS code
- 2007
-
In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 40:9, s. 1320-1331
-
Journal article (peer-reviewed)abstract
- Many new options have recently been included in PHITS, e.g., to calculate LET distributions of particles in matter or energy-deposition distributions event by event and correlations between energy depositions in different regions. This makes it possible to calculate the effects of particle radiation on biological and non-biological materials, e.g., risk for single event upsets in electronic devices. As a part of an extensive ongoing benchmarking of PHITS, we have compared calculated partial projectile fragmentation cross sections with accelerator-based measurements from the reactions of 200-1000 MeV/n He-4, C-12, N-14, O-16, Ne-20, Si-28, Ar-40, and Fe-56 on polyethylene, carbon, aluminum, copper, tin and lead, with different thicknesses, using different total reaction cross section models in PHITS. We have compared simulated and measured Bragg and attenuation curves of 200 MeV/n C-12 in water, and neutron energy spectra, at different angles, from 100 to 400 MeV/n C-12 stopped in water. Bragg curves for 110, 140, 170, 190 and 225 MeV/n He-3 in water have been studied, as well as gamma-ray dose decay curves of activated Cu target bombarded by 400 and 800 MeV/n Ar-40. When using the default total reaction cross section model developed by Tripathi et al. (1996,1997 and 1999) [Tripathi, R.K., Cucinotta, F.A., Wilson, J.W. Accurate universal parameterization of absorption cross sections, Nucl. Instr. Methods B117, 347, 1996; Tripathi, R.K., Wilson, J.W., Cucinotta, F.A. Accurate universal parameterization of absorption cross sections II - neutron absorption cross sections. Nucl. Instr. Methods B129, 11, 1997; Tripathi, R.K., Cucinotta, F.A., Wilson, J.W. Accurate universal parameterization of absorption cross sections III - light systems. Nucl. Instr. Methods B155, 349, 1999.] the partial fragmentation cross sections appear to be systematically slightly underestimated by a factor which is independent on the fragment species within the same data set, and so do the simulated neutron energy spectra from selected heavy ion reactions; especially in the forward direction. The simulated attenuation and Bragg curves, however, show good agreement with measured ones. These observations stimulate further benchmarking to confirm the accuracy of the code and gives directions on possible improvements to be applied to the code in the near future. (C) 2007 Published by Elsevier Ltd on behalf of COSPAR.
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| 32. |
- Sihver, Lembit, 1962, et al.
(author)
-
Simulations of th MTR-R and MTR Experiments at ISS, and Shielding Properties using PHITS
- 2009
-
In: IEEE Aerospace Conference Proceedings. - 1095-323X. - 9781424426218
-
Conference paper (peer-reviewed)abstract
- Concerns about the biological effects of space radiation are increasing rapidly due to the perspective of long-duration manned missions, both in relation to the International Space Station (ISS) and to manned interplanetary missions to the Moon and Mars in the future. As a preparation for these long duration space missions it is important to ensure an excellent capability to evaluate the impact of space radiation on human health in order to secure the safety of the astronauts/cosmonauts and minimize their risks. It is therefore necessary to measure the radiation load on the personnel both inside and outside the space vehicles and certify that organ and tissue equivalent doses can be simulated as accurate as possible. In this paper we will present preliminary results from simulations, using the three-dimensional Monte Carlo Particle and Heavy Ions Transport code System (PHITS), of long term dose distribution measurements performed with the joint ESA-FSA experiment MATROSHKA-R (MTR-R) led by the Russian Federation Institute of Biomedical Problems (IMBP). MTR-R is a spherical phantom located inside the crew cabin of ISS. We also show some results from PHITS simulations of the ESA supported experiment MATROSHKA (MTR), which consists of an anthropomorphic phantom containing over 6000 radiation detectors, mimicking a human head and torso. The MTR experiment, led by the German Aerospace Center (DLR), was launched in January 2004 and has measured the absorbed dose from space radiation both inside and outside the ISS. In this paper preliminary comparisons of measurements outside the ISS will be presented. For the purpose of examining the applicability of PHITS to the shielding design, the absorbed doses and dose equivalents in a cylindrical phantom with tissue equivalent material inside an imaginary space vessel on a geostationary orbit at solar minimum has also been estimated for different shielding materials of different thicknesses. All the results indicate that PHITS is - a suitable tool when estimating radiation risks for humans on manned space missions and when performing shielding design studies of spacecraft.
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| 33. |
- Sihver, Lembit, 1962
(author)
-
Transport calculations and accelerator experiments needed for radiation risk assessment in space
- 2008
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In: Zeitschrift für Medizinische Physik. - : Elsevier BV. - 0939-3889. ; 18:4, s. 253-264
-
Research review (peer-reviewed)abstract
- The major uncertainties on space radiation risk estimates in humans are associated to the poor knowledge of the biological effects of low and high LET radiation, with a smaller contribution coming from the characterization of space radiation field and its primary interactions with the shielding and the human body. However, to decrease the uncertainties on the biological effects and increase the accuracy of the risk coefficients for charged particles radiation, the initial charged-particle spectra from the Galactic Cosmic Rays (GCRs) and the Solar Particle Events (SPEs), and the radiation transport through the shielding material of the space vehicle and the human body, must be better estimated. Since it is practically impossible to measure all primary and secondary particles from all possible position-projectile-target-energy combinations needed for a correct risk assessment in space, accurate particle and heavy ion transport codes must be used. These codes are also needed when estimating the risk for radiation induced failures in advanced microelectronics, such as single-event effects, etc., and the efficiency of different shielding materials. It is therefore important that the models and transport codes will be carefully benchmarked and validated to make sure they fulfill preset accuracy criteria, e.g. to be able to predict particle fluence, dose and energy distributions within a certain accuracy. When validating the accuracy of the transport codes, both space and ground based accelerator experiments are needed. The efficiency of passive shielding and protection of electronic devices should also be tested in accelerator experiments and compared to simulations using different transport codes. In this paper different multi-purpose particle and heavy ion transport codes will be presented, different concepts of shielding and protection discussed, as well as future accelerator experiments needed for testing and validating codes and shielding materials. © 2008.
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| 34. |
- Toshito, T., et al.
(author)
-
Measurements of projectile-like Be-8 and B-9 production in 200-400 MeV/nucleon C-12 on water
- 2008
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 78:6, s. 4-
-
Journal article (peer-reviewed)abstract
- We have studied the production of the projectile-like fragments Be-8 and B-9 produced in interactions of 200 to 400 MeV/nucleon carbon ions with water, using emulsion detectors. In this Brief Report we present the first published production cross section of the projectile-like fragment B-9 in the energy region above 100 MeV/nucleon. The measured production cross sections of these nuclides were compared to calculations using a semiempirical model. We found that the measured cross sections deviate from the calculated values by a factor up to about six. This information is of importance for benchmarking and improving heavy ion nuclear reaction models.
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| 35. |
- Toshito, T., et al.
(author)
-
Measurements of total and partial charge-changing cross sections for 200-to 400-MeV/nucleon C-12 on water and polycarbonate
- 2007
-
In: Physical Review C - Nuclear Physics. - 2469-9985 .- 2469-9993. ; 75:5, s. 8-
-
Journal article (peer-reviewed)abstract
- We have studied charged nuclear fragments produced by 200- to 400-MeV/nucleon carbon ions, interacting with water and polycarbonate, using a newly developed emulsion detector. Total and partial charge-changing cross sections for the production of B, Be, and Li fragments were measured and compared with both previously published measurements and model predictions. This study is of importance for validating and improving carbon-ion therapy treatment planning systems and for estimating the radiological risks for personnel on space missions, because carbon is a significant component of galactic cosmic rays.
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| 36. |
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| 37. |
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| 38. |
- Zeitlin, C., et al.
(author)
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Fragmentation Cross Sections of Medium-Energy 35Cl, 40Ar, and 48Ti Beams on Elemental Targets
- 2008
-
In: Physical Review. ; :C77, s. 034605-
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Journal article (peer-reviewed)abstract
- Charge-changing and fragment production cross sections at 0 degrees have been obtained for interactions of 290, 400, and 650 MeV/nucleon 40Ar beams, 650 and 1000 MeV/nucleon 35Cl beams, and a 1000 MeV/nucleon 48Ti beam. Targets of C, CH2, Al, Cu, Sn, and Pb were used. Using standard analysis methods, we obtain fragment cross sections for charges as low as 8 for Cl and Ar beams, and as low as 10 for the Ti beam. Using data obtained with small-acceptance detectors, we report fragment production cross sections for charges as low as 5, corrected for acceptance using a simple model of fragment angular distributions. With the lower-charged fragment cross sections, we cancompare the data to predictions from several models (including NUCFRG2, EPAX2, and PHITS) in a region largely unexplored in earlier work. As found in earlier work with other beams, NUCFRG2 and PHITS predictions agree reasonably well with the data for charge-changing cross sections, but do not accurately predict the fragment production cross sections. The cross sections for the lightest fragments demonstrate the inadequacy of several models in which the cross sections fall monotonically with the charge of the fragment. PHITS, despite not agreeing particularly well with the fragment production cross sections on average, nonetheless qualitatively reproduces somesignificant features of the data that are missing from the other models.
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