| 1. |
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| 2. |
- 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
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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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| 3. |
- Sihver, Lembit, 1962, et al.
(author)
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An update about recent developments of the PHITS code
- 2010
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 45:7, s. 892-899
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Journal article (peer-reviewed)abstract
- PHITS (Particle and Heavy-Ion Transport code System) is a general-purpose three-dimensional Monte Carlo code, developed and maintained by RIST, JAEA and KEK in Japan together with Sihver et al. at Chalmers in Sweden. PHITS can deal with the transports of all varieties of hadrons and heavy ions with energies up to around 100 GeV/nucleon, and in this paper the current status of PHITS is presented. We introduce a relativistically covariant version of JQMD, called R-JQMD, that features an improved ground state initialization algorithm, and we will present the introduction of electron and photon transport in PHITS using EGS5, which have increased the energy region for the photon and energy transport from up to around 3 GeV to up to several hundred GeV depending on the atomic number of the target. We show how the accuracy in dose and fluence calculations can be improved by using tabulated cross sections. Benchmarking of shielding and irradiation effects of high energy protons in different materials relevant for shielding of accelerator facilities is also presented. In particular, we show that PHITS can be used for estimating the dose received by aircrews and personnel in space. In recent years, many countries have issued regulations or recommendations to set annual dose limitations for aircrews. Since estimation of cosmic-ray spectra in the atmosphere is an essential issue for the evaluation of aviation doses, we have calculated these spectra using PHITS. The accuracy of the atmospheric propagation simulation of cosmic-ray performed by PHITS has been well verified by experimental cosmic-ray spectra taken under various conditions. Based on a comprehensive analysis of the simulation results, an analytical model called "PARMA" has been proposed for instantaneously estimating the atmospheric cosmic-ray spectra below the altitude of 20 km. We have also performed preliminary simulations of long-term dose distribution measurements at the ISS performed with the joint ESA-FSA experiment MATROSHKA-R (MTR-R) led by the Russian Federation Institute of Biomedical Problems (IMBP) and the ESA supported experiment MATROSHKA (MTR), led by the German Aerospace Center (DLR). For the purpose of examining the applicability of PHITS to the shielding design in space, the absorbed doses in a tissue equivalent water phantom inside an imaginary space vessel has been estimated for different shielding materials of different thicknesses. The results confirm previous results which indicate that PHITS is a suitable tool when performing shielding design studies of spacecrafts. (C) 2010 COSPAR. Published by Elsevier Ltd. All rights reserved.
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| 4. |
- Bertucci, Antonella, et al.
(author)
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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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| 5. |
- 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
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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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| 6. |
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| 7. |
- 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
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In: Radiation and Environmental Biophysics. - 1432-2099 .- 0301-634X. ; 48:2, s. 135-143
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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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| 8. |
- Mancusi, Davide, 1980, et al.
(author)
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Comparison of aluminum and lucite for shielding against 1 GeV protons
- 2007
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 40:4, s. 581-585
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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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| 9. |
- Mancusi, Davide, 1980
(author)
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Heavy-ion transport codes for radiotherapy and radioprotection in space
- 2006
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Licentiate thesis (other academic/artistic)abstract
- Simulation of the transport of heavy ions in matter is a field of nuclear science that has recently received attention in view of its importance for some relevant applications. Accelerated heavy ions can, for example, be used to treat cancers (heavy-ion radiotherapy) and show some superior qualities with respect to more conventional treatment systems, like photons (x-rays) or protons. Furthermore, long-term manned space missions (like a possible future mission to Mars) pose the challenge to protect astronauts and equipment on board against the harmful space radiation environment, where heavy ions can be responsible for a significant share of the exposure risk.The high accuracy expected from a transport algorithm (especially in the case of radiotherapy) and the large amount of semi-empirical knowledge necessary to even state the transport problem properly rule out any analytical approach; the alternative is to resort to numerical simulations in order to build treatment-planning systems for cancer or to aid space engineers in shielding design. This thesis is focused on the description of HIBRAC, a one-dimensional deterministic code optimised for radiotherapy, and PHITS (Particle and Heavy-Ion Transport System), a general-purpose three-dimensional Monte-Carlo code. The structure of both codes is outlined and some relevant results are presented. In the case of PHITS, we also report the first results of an ongoing comprehensive benchmarking program for the main components of the code; we present the comparison of partial charge-changing cross sections for a 400 MeV/n Ar-40 beam impinging on carbon, polyethylene, aluminium, copper, tin and lead targets.
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| 10. |
- Mancusi, Davide, 1980
(author)
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Radiation and matter: how do they play with each other?
- 2008
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Doctoral thesis (other academic/artistic)abstract
- The propagation of radiation is affected by the presence of matter; at the same time, the physicochemical properties of matter are modified by the passage of radiation. The interplay of radiation and matter is of crucial importance in many modern applications: accelerated heavy ions, in particular, can be used in radiotherapeutical treatments of some cancers; moreover, they are present in the space radiation environment and represent a serious threat to the health of spaceship crews and to the functionality of electronic equipment on board.Quantitative predictions of the effects of radiation on matter and of matter on radiation consist often in numerical estimates obtained with transport codes, computer programs built on theoretical, semi-empirical and/or empirical models describing the microscopic processes that govern radiation-matter interaction. The validity of a transport code for a particular task depends directly on the accuracy of the models it uses. It is therefore very important to develop reliable microscopic models and demonstrate their suitability for the inclusion in transport codes.Indeed, the objects of this thesis are the development and the benchmarking of computer codes and microscopic models for the simulation of heavy-ion transport. We developed a semi-empirical model for the prediction of partial charge-changing cross sections for heavy ions, based on the experimentally verified weak-factorisation systematics. We also performed an extensive benchmark of partial charge-changing cross sections calculated with a number of nuclear-reaction event generators; the JQMD (JAERI Quantum Molecular Dynamics) event generator, in particular, was upgraded with the goal of improving its performance in soft, peripheral reactions.Finally, the utility of transport codes to real problems is demonstrated by application to actual problems in radiotherapy and radioprotection in space. Transport codes prove to be precious tools in the interpretation of controversial experimental data and in designand planning of equipment and shielding for several applications.
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| 11. |
- 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
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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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| 12. |
- Sato, T., et al.
(author)
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Evaluation of dose rate reduction in a spacecraft compartment due to additional water shield
- 2011
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In: Cosmic Research (English translation of Kosimicheskie Issledovaniya). - 0010-9525 .- 1608-3075. ; 49:4, s. 319-324
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Journal article (peer-reviewed)abstract
- The dose reduction rates brought about by the installation of additional water shielding in a spacecraft are calculated in the paper using the particles and heavy ion transport code system PHITS, which can deal with transport of all kinds of hadrons and heavy ions with energies up to 100 GeV/n in three-dimensional phase spaces. In the PHITS simulation, an imaginary spacecraft was irradiated isotropically by cosmic rays with charges up to 28 and energies up to 100 GeV/n, and the dose reduction rates due to water shielding were evaluated for 5 types of doses: the dose equivalents obtained from the LET and linear energy spectra, the dose equivalents to skin and red bone marrow, and the effective dose equivalent. The results of the simulation indicate that the dose reduction rates differ according to the type of dose evaluated. For example, 5 g/cm(2) water shielding reduces the effective dose equivalent and the LET dose equivalent by approximately 14% and 32%, respectively. Such degrees of dose reduction can be regarded to make water shielding worth the efforts required to install it.
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| 13. |
- 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
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In: Acta Astronautica. - : Elsevier BV. - 0094-5765. ; 63:7-10, s. 865-877
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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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| 14. |
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| 15. |
- Sihver, Lembit, 1962, et al.
(author)
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Present status and validation of HIBRAC
- 2009
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In: Radiation Measurements. - : Elsevier BV. - 1350-4487. ; 44:1, s. 38-46
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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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| 16. |
- Sihver, Lembit, 1962, et al.
(author)
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Recent developments and benchmarking of the PHITS code
- 2007
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In: Advances in Space Research. - : Elsevier BV. - 1879-1948 .- 0273-1177. ; 40:9, s. 1320-1331
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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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