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Sample records for geant4 physics models

  1. Implementation of new physics models for low energy electrons in liquid water in Geant4-DNA.

    PubMed

    Bordage, M C; Bordes, J; Edel, S; Terrissol, M; Franceries, X; Bardiès, M; Lampe, N; Incerti, S

    2016-12-01

    A new alternative set of elastic and inelastic cross sections has been added to the very low energy extension of the Geant4 Monte Carlo simulation toolkit, Geant4-DNA, for the simulation of electron interactions in liquid water. These cross sections have been obtained from the CPA100 Monte Carlo track structure code, which has been a reference in the microdosimetry community for many years. They are compared to the default Geant4-DNA cross sections and show better agreement with published data. In order to verify the correct implementation of the CPA100 cross section models in Geant4-DNA, simulations of the number of interactions and ranges were performed using Geant4-DNA with this new set of models, and the results were compared with corresponding results from the original CPA100 code. Good agreement is observed between the implementations, with relative differences lower than 1% regardless of the incident electron energy. Useful quantities related to the deposited energy at the scale of the cell or the organ of interest for internal dosimetry, like dose point kernels, are also calculated using these new physics models. They are compared with results obtained using the well-known Penelope Monte Carlo code. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  2. Validation of Geant4 physics models for 56Fe ion beam in various media

    NASA Astrophysics Data System (ADS)

    Jalota, Summit; Kumar, Ashavani

    2012-11-01

    The depth-dose distribution of a 56Fe ion beam has been studied in water, polyethylene, nextel, kevlar and aluminum media. The dose reduction versus areal depth is also calculated for 56Fe ions in carbon, polyethylene and aluminum using the Monte Carlo simulation toolkit Geant4. This study presents the validation of physics models available in Geant4 by comparing the simulated results with the experimental data available in the literature. Simulations are performed using binary cascade (BIC), abrasion-ablation (AA) and quantum molecular dynamics (QMD) models; integrated into Geant4. Deviations from experimental results may be due to the selection of simple geometry. This paper also addresses the differences in the simulated results from various models.

  3. Preliminary Investigation of Microdosimetric Track Structure Physics Models in Geant4-DNA and RITRACKS

    PubMed Central

    Bezak, Eva

    2015-01-01

    The major differences between the physics models in Geant4-DNA and RITRACKS Monte Carlo packages are investigated. Proton and electron ionisation interactions and electron excitation interactions in water are investigated in the current work. While these packages use similar semiempirical physics models for inelastic cross-sections, the implementation of these models is demonstrated to be significantly different. This is demonstrated in a simple Monte Carlo simulation designed to identify differences in interaction cross-sections. PMID:26124856

  4. Low-energy electron dose-point kernel simulations using new physics models implemented in Geant4-DNA

    NASA Astrophysics Data System (ADS)

    Bordes, Julien; Incerti, Sébastien; Lampe, Nathanael; Bardiès, Manuel; Bordage, Marie-Claude

    2017-05-01

    When low-energy electrons, such as Auger electrons, interact with liquid water, they induce highly localized ionizing energy depositions over ranges comparable to cell diameters. Monte Carlo track structure (MCTS) codes are suitable tools for performing dosimetry at this level. One of the main MCTS codes, Geant4-DNA, is equipped with only two sets of cross section models for low-energy electron interactions in liquid water (;option 2; and its improved version, ;option 4;). To provide Geant4-DNA users with new alternative physics models, a set of cross sections, extracted from CPA100 MCTS code, have been added to Geant4-DNA. This new version is hereafter referred to as ;Geant4-DNA-CPA100;. In this study, ;Geant4-DNA-CPA100; was used to calculate low-energy electron dose-point kernels (DPKs) between 1 keV and 200 keV. Such kernels represent the radial energy deposited by an isotropic point source, a parameter that is useful for dosimetry calculations in nuclear medicine. In order to assess the influence of different physics models on DPK calculations, DPKs were calculated using the existing Geant4-DNA models (;option 2; and ;option 4;), newly integrated CPA100 models, and the PENELOPE Monte Carlo code used in step-by-step mode for monoenergetic electrons. Additionally, a comparison was performed of two sets of DPKs that were simulated with ;Geant4-DNA-CPA100; - the first set using Geant4‧s default settings, and the second using CPA100‧s original code default settings. A maximum difference of 9.4% was found between the Geant4-DNA-CPA100 and PENELOPE DPKs. Between the two Geant4-DNA existing models, slight differences, between 1 keV and 10 keV were observed. It was highlighted that the DPKs simulated with the two Geant4-DNA's existing models were always broader than those generated with ;Geant4-DNA-CPA100;. The discrepancies observed between the DPKs generated using Geant4-DNA's existing models and ;Geant4-DNA-CPA100; were caused solely by their different cross

  5. A Software Toolkit to Study Systematic Uncertainties of the Physics Models of the Geant4 Simulation Package

    SciTech Connect

    Genser, Krzysztof; Hatcher, Robert; Perdue, Gabriel; Wenzel, Hans; Yarba, Julia; Kelsey, Michael; Wright, Dennis H.

    2016-11-10

    The Geant4 toolkit is used to model interactions between particles and matter. Geant4 employs a set of validated physics models that span a wide range of interaction energies. These models are tuned to cover a large variety of possible applications. This raises the critical question of what uncertainties are associated with the Geant4 physics model, or group of models, involved in a simulation project. To address the challenge, we have designed and implemented a comprehen- sive, modular, user-friendly software toolkit that allows the variation of one or more parameters of one or more Geant4 physics models involved in simulation studies. It also enables analysis of multiple variants of the resulting physics observables of interest in order to estimate the uncertain- ties associated with the simulation model choices. Key functionalities of the toolkit are presented in this paper and are illustrated with selected results.

  6. Validation of Hadronic Models in GEANT4

    SciTech Connect

    Koi, Tatsumi; Wright, Dennis H.; Folger, Gunter; Ivanchenko, Vladimir; Kossov, Mikhail; Starkov, Nikolai; Heikkinen, Aatos; Truscott, Peter; Lei, Fan; Wellisch, Hans-Peter

    2007-09-26

    Geant4 is a software toolkit for the simulation of the passage of particles through matter. It has abundant hadronic models from thermal neutron interactions to ultra relativistic hadrons. An overview of validations in Geant4 hadronic physics is presented based on thin target measurements. In most cases, good agreement is available between Monte Carlo prediction and experimental data; however, several problems have been detected which require some improvement in the models.

  7. The Geant4 physics validation repository

    DOE PAGES

    Wenzel, H.; Yarba, J.; Dotti, A.

    2015-12-23

    The Geant4 collaboration regularly performs validation and regression tests. The results are stored in a central repository and can be easily accessed via a web application. In this article we describe the Geant4 physics validation repository which consists of a relational database storing experimental data and Geant4 test results, a java API and a web application. Lastly, the functionality of these components and the technology choices we made are also described

  8. Implementing NRF Physics in Geant4

    SciTech Connect

    Jordan, David V.; Warren, Glen A.

    2006-07-01

    The Geant4 radiation transport Monte Carlo code toolkit currently does not support nuclear resonance fluorescence (NRF). After a brief review of NRF physics, plans for implementing this physics process in Geant4, and validating the output of the code, are described. The plans will be executed as Task 3 of project 50799, "Nuclear Resonance Fluorescence Signatures (NuRFS)".

  9. Geant4 physics processes for microdosimetry simulation: Very low energy electromagnetic models for protons and heavy ions in silicon

    NASA Astrophysics Data System (ADS)

    Valentin, A.; Raine, M.; Gaillardin, M.; Paillet, P.

    2012-09-01

    The Geant4-DNA extension of the Geant4 Monte Carlo simulation toolkit aims at modeling early biological damages induced by ionizing radiation at the DNA scale, and it can now track particles down to very low energies in liquid water. New models, called "MuElec", have been implemented for microelectronic applications following the same initial theory, to track low energy electrons in silicon. This paper presents the extension of these MuElec models to incident protons and heavy ions in silicon. First, the theory of the model is presented. The resulting cross sections and stopping powers are compared with data from the literature. The model is then implemented in Geant4 and used to simulate proton tracks. Various physical quantities are extracted from the simulation, and compared with data from the literature and with results from simulation using other Geant4 models. It is shown that the generation of low-energy electrons results in more physically meaningful low-energy secondary electron tracks, which significantly modifies the proton and ion track core on the nanometer scale.

  10. GEANT4: Applications in High Energy Physics

    SciTech Connect

    Mahmood, Tariq; Zafar, Abrar Ahmed; Hussain, Talib; Rashid, Haris

    2007-02-14

    GEANT4 is a detector simulation toolkit aimed at studying, mainly experimental high energy physics. In this paper we will give an overview of this software with special reference to its applications in high energy physics experiments. A brief of process methods is given. Object-oriented nature of the simulation toolkit is highlighted.

  11. Geant4 models for space radiation environment.

    NASA Astrophysics Data System (ADS)

    Ivantchenko, Anton; Nieminen, Petteri; Incerti, Sebastien; Santin, Giovanni; Ivantchenko, Vladimir; Grichine, Vladimir; Allison, John

    The space radiation environment includes wide varieties of particles from electrons to heavy ions. In order to correctly predict the dose received by astronauts and devices the simulation models must have good applicability and produce accurate results from 10 MeV/u up to 10 GeV/u, where the most radioactive hazardous particles are present in the spectra. Appropriate models should also provide a good description of electromagnetic interactions down to very low energies (10 eV/u - 10 MeV/u) for understanding the damage mechanisms due to long-term low doses. Predictions of biological dose during long interplanetary journeys also need models for hadronic interactions of energetic heavy ions extending higher energies (10 GeV/u - 100 GeV/u, but possibly up to 1 TeV/u). Geant4 is a powerful toolkit, which in some areas well surpasses the needs from space radiation studies, while in other areas is being developed and/or validated to properly cover the modelling requirements outlined above. Our activities in ESA projects deal with the research and development of both Geant4 hadronic and electromagnetic physics. Recently the scope of verification tests and benchmarks has been extended. Hadronic tests and benchmarks run proton, pion, and ion interactions with matter at various energies. In the Geant4 hadronic sub-libraries, the most accurate cross sections have been identified and selected as a default for all particle types relevant to space applications. Significant developments were carried out for ion/ion interaction models. These now allow one to perform Geant4 simulations for all particle types and energies relevant to space applications. For the validation of ion models the hadronic testing suite for ion interactions was significantly extended. In this work the results of benchmarking versus data in a wide energy range for projectile protons and ions will be shown and discussed. Here we show results of the tests runs and their precision. Recommendations for Geant4

  12. Calibrating a physical model based on Geant4 to calculate cosmogenic nuclide production rates on lunar surface

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Dong, Tiekuang; Ren, Zhongzhou

    2017-04-01

    A physical model based on the open-source toolkit Geant4 for production rates of cosmogenic nuclei on the lunar surface is proposed and calibrated. The fluxes of proton and neutron beneath the lunar surface are obtained by simulating the physical processes between the cosmic-ray particles and the lunar surface material. By combining the experimental proton cross sections and the a posteriori neutron cross sections, we calculate the production rate depth profiles of long-lived nuclei (10Be, 14C, 26Al, 36Cl, and 53Mn). Through comparing experimental and theoretical data for these nuclei, we find that for all the selected nuclei, experimental and theoretical production rate depth profiles agree well with each other by introducing a single normalization factor. It means that the physical model based on Geant4 can also reproduce the depth profiles of cosmogenic nuclei, and that this model can be used by everyone worldwide. In addition, we predict the production rates of three stable nuclei (21Ne, 22Ne, and 38Ar).

  13. Geant4 hadronic physics for space radiation environment.

    PubMed

    Ivantchenko, Anton V; Ivanchenko, Vladimir N; Molina, Jose-Manuel Quesada; Incerti, Sebastien L

    2012-01-01

    To test and to develop Geant4 (Geometry And Tracking version 4) Monte Carlo hadronic models with focus on applications in a space radiation environment. The Monte Carlo simulations have been performed using the Geant4 toolkit. Binary (BIC), its extension for incident light ions (BIC-ion) and Bertini (BERT) cascades were used as main Monte Carlo generators. For comparisons purposes, some other models were tested too. The hadronic testing suite has been used as a primary tool for model development and validation against experimental data. The Geant4 pre-compound (PRECO) and de-excitation (DEE) models were revised and improved. Proton, neutron, pion, and ion nuclear interactions were simulated with the recent version of Geant4 9.4 and were compared with experimental data from thin and thick target experiments. The Geant4 toolkit offers a large set of models allowing effective simulation of interactions of particles with matter. We have tested different Monte Carlo generators with our hadronic testing suite and accordingly we can propose an optimal configuration of Geant4 models for the simulation of the space radiation environment.

  14. Experimental quantification of Geant4 PhysicsList recommendations: methods and results

    NASA Astrophysics Data System (ADS)

    Basaglia, Tullio; Han, Min Cheol; Hoff, Gabriela; Kim, Chan Hyeong; Kim, Sung Hun; Grazia Pia, Maria; Saracco, Paolo

    2015-12-01

    The Geant4 physicsjists package encompasses predefined selections of physics processes and models to be used in simulation applications. Limited documentation is available in the literature about Geant4 pre-packaged PhysicsLists and their validation. The reports in the literature mainly concern specific use cases. This paper documents the epistemological grounds for the validation of Geant4 pre-packaged PhysicsLists (and their accessory classes, Builders and PhysicsConstructors) and some examples of the author's scientific activity on this subject.

  15. Comparison of GEANT4 very low energy cross section models with experimental data in water

    SciTech Connect

    Incerti, S.; Ivanchenko, A.; Karamitros, M.; Mantero, A.; Moretto, P.; Tran, H. N.; Mascialino, B.; Champion, C.; Ivanchenko, V. N.; Bernal, M. A.; Francis, Z.; Villagrasa, C.; Baldacchino, G.; Gueye, P.; Capra, R.; Nieminen, P.; Zacharatou, C.

    2010-09-15

    Purpose: The GEANT4 general-purpose Monte Carlo simulation toolkit is able to simulate physical interaction processes of electrons, hydrogen and helium atoms with charge states (H{sup 0}, H{sup +}) and (He{sup 0}, He{sup +}, He{sup 2+}), respectively, in liquid water, the main component of biological systems, down to the electron volt regime and the submicrometer scale, providing GEANT4 users with the so-called ''GEANT4-DNA'' physics models suitable for microdosimetry simulation applications. The corresponding software has been recently re-engineered in order to provide GEANT4 users with a coherent and unique approach to the simulation of electromagnetic interactions within the GEANT4 toolkit framework (since GEANT4 version 9.3 beta). This work presents a quantitative comparison of these physics models with a collection of experimental data in water collected from the literature. Methods: An evaluation of the closeness between the total and differential cross section models available in the GEANT4 toolkit for microdosimetry and experimental reference data is performed using a dedicated statistical toolkit that includes the Kolmogorov-Smirnov statistical test. The authors used experimental data acquired in water vapor as direct measurements in the liquid phase are not yet available in the literature. Comparisons with several recommendations are also presented. Results: The authors have assessed the compatibility of experimental data with GEANT4 microdosimetry models by means of quantitative methods. The results show that microdosimetric measurements in liquid water are necessary to assess quantitatively the validity of the software implementation for the liquid water phase. Nevertheless, a comparison with existing experimental data in water vapor provides a qualitative appreciation of the plausibility of the simulation models. The existing reference data themselves should undergo a critical interpretation and selection, as some of the series exhibit significant

  16. Track structure modeling in liquid water: A review of the Geant4-DNA very low energy extension of the Geant4 Monte Carlo simulation toolkit.

    PubMed

    Bernal, M A; Bordage, M C; Brown, J M C; Davídková, M; Delage, E; El Bitar, Z; Enger, S A; Francis, Z; Guatelli, S; Ivanchenko, V N; Karamitros, M; Kyriakou, I; Maigne, L; Meylan, S; Murakami, K; Okada, S; Payno, H; Perrot, Y; Petrovic, I; Pham, Q T; Ristic-Fira, A; Sasaki, T; Štěpán, V; Tran, H N; Villagrasa, C; Incerti, S

    2015-12-01

    Understanding the fundamental mechanisms involved in the induction of biological damage by ionizing radiation remains a major challenge of today's radiobiology research. The Monte Carlo simulation of physical, physicochemical and chemical processes involved may provide a powerful tool for the simulation of early damage induction. The Geant4-DNA extension of the general purpose Monte Carlo Geant4 simulation toolkit aims to provide the scientific community with an open source access platform for the mechanistic simulation of such early damage. This paper presents the most recent review of the Geant4-DNA extension, as available to Geant4 users since June 2015 (release 10.2 Beta). In particular, the review includes the description of new physical models for the description of electron elastic and inelastic interactions in liquid water, as well as new examples dedicated to the simulation of physicochemical and chemical stages of water radiolysis. Several implementations of geometrical models of biological targets are presented as well, and the list of Geant4-DNA examples is described.

  17. Diffusion-controlled reactions modeling in Geant4-DNA

    NASA Astrophysics Data System (ADS)

    Karamitros, M.; Luan, S.; Bernal, M. A.; Allison, J.; Baldacchino, G.; Davidkova, M.; Francis, Z.; Friedland, W.; Ivantchenko, V.; Ivantchenko, A.; Mantero, A.; Nieminem, P.; Santin, G.; Tran, H. N.; Stepan, V.; Incerti, S.

    2014-10-01

    Context Under irradiation, a biological system undergoes a cascade of chemical reactions that can lead to an alteration of its normal operation. There are different types of radiation and many competing reactions. As a result the kinetics of chemical species is extremely complex. The simulation becomes then a powerful tool which, by describing the basic principles of chemical reactions, can reveal the dynamics of the macroscopic system. To understand the dynamics of biological systems under radiation, since the 80s there have been on-going efforts carried out by several research groups to establish a mechanistic model that consists in describing all the physical, chemical and biological phenomena following the irradiation of single cells. This approach is generally divided into a succession of stages that follow each other in time: (1) the physical stage, where the ionizing particles interact directly with the biological material; (2) the physico-chemical stage, where the targeted molecules release their energy by dissociating, creating new chemical species; (3) the chemical stage, where the new chemical species interact with each other or with the biomolecules; (4) the biological stage, where the repairing mechanisms of the cell come into play. This article focuses on the modeling of the chemical stage. Method This article presents a general method of speeding-up chemical reaction simulations in fluids based on the Smoluchowski equation and Monte-Carlo methods, where all molecules are explicitly simulated and the solvent is treated as a continuum. The model describes diffusion-controlled reactions. This method has been implemented in Geant4-DNA. The keys to the new algorithm include: (1) the combination of a method to compute time steps dynamically with a Brownian bridge process to account for chemical reactions, which avoids costly fixed time step simulations; (2) a k-d tree data structure for quickly locating, for a given molecule, its closest reactants. The

  18. Diffusion-controlled reactions modeling in Geant4-DNA

    SciTech Connect

    Karamitros, M.; Luan, S.; Bernal, M.A.; Allison, J.; Baldacchino, G.; Davidkova, M.; Francis, Z.; Friedland, W.; Ivantchenko, V.; Ivantchenko, A.; Mantero, A.; Nieminem, P.; Santin, G.; Tran, H.N.; Stepan, V.; Incerti, S.

    2014-10-01

    Context Under irradiation, a biological system undergoes a cascade of chemical reactions that can lead to an alteration of its normal operation. There are different types of radiation and many competing reactions. As a result the kinetics of chemical species is extremely complex. The simulation becomes then a powerful tool which, by describing the basic principles of chemical reactions, can reveal the dynamics of the macroscopic system. To understand the dynamics of biological systems under radiation, since the 80s there have been on-going efforts carried out by several research groups to establish a mechanistic model that consists in describing all the physical, chemical and biological phenomena following the irradiation of single cells. This approach is generally divided into a succession of stages that follow each other in time: (1) the physical stage, where the ionizing particles interact directly with the biological material; (2) the physico-chemical stage, where the targeted molecules release their energy by dissociating, creating new chemical species; (3) the chemical stage, where the new chemical species interact with each other or with the biomolecules; (4) the biological stage, where the repairing mechanisms of the cell come into play. This article focuses on the modeling of the chemical stage. Method This article presents a general method of speeding-up chemical reaction simulations in fluids based on the Smoluchowski equation and Monte-Carlo methods, where all molecules are explicitly simulated and the solvent is treated as a continuum. The model describes diffusion-controlled reactions. This method has been implemented in Geant4-DNA. The keys to the new algorithm include: (1) the combination of a method to compute time steps dynamically with a Brownian bridge process to account for chemical reactions, which avoids costly fixed time step simulations; (2) a k–d tree data structure for quickly locating, for a given molecule, its closest reactants. The

  19. Modeling the relativistic runaway electron avalanche and the feedback mechanism with GEANT4

    PubMed Central

    Skeltved, Alexander Broberg; Østgaard, Nikolai; Carlson, Brant; Gjesteland, Thomas; Celestin, Sebastien

    2014-01-01

    This paper presents the first study that uses the GEometry ANd Tracking 4 (GEANT4) toolkit to do quantitative comparisons with other modeling results related to the production of terrestrial gamma ray flashes and high-energy particle emission from thunderstorms. We will study the relativistic runaway electron avalanche (RREA) and the relativistic feedback process, as well as the production of bremsstrahlung photons from runaway electrons. The Monte Carlo simulations take into account the effects of electron ionization, electron by electron (Møller), and electron by positron (Bhabha) scattering as well as the bremsstrahlung process and pair production, in the 250 eV to 100 GeV energy range. Our results indicate that the multiplication of electrons during the development of RREAs and under the influence of feedback are consistent with previous estimates. This is important to validate GEANT4 as a tool to model RREAs and feedback in homogeneous electric fields. We also determine the ratio of bremsstrahlung photons to energetic electrons Nγ/Ne. We then show that the ratio has a dependence on the electric field, which can be expressed by the avalanche time τ(E) and the bremsstrahlung coefficient α(ε). In addition, we present comparisons of GEANT4 simulations performed with a “standard” and a “low-energy” physics list both validated in the 1 keV to 100 GeV energy range. This comparison shows that the choice of physics list used in GEANT4 simulations has a significant effect on the results. Key Points Testing the feedback mechanism with GEANT4 Validating the GEANT4 programming toolkit Study the ratio of bremsstrahlung photons to electrons at TGF source altitude PMID:26167437

  20. Modeling the relativistic runaway electron avalanche and the feedback mechanism with GEANT4.

    PubMed

    Skeltved, Alexander Broberg; Østgaard, Nikolai; Carlson, Brant; Gjesteland, Thomas; Celestin, Sebastien

    2014-11-01

    This paper presents the first study that uses the GEometry ANd Tracking 4 (GEANT4) toolkit to do quantitative comparisons with other modeling results related to the production of terrestrial gamma ray flashes and high-energy particle emission from thunderstorms. We will study the relativistic runaway electron avalanche (RREA) and the relativistic feedback process, as well as the production of bremsstrahlung photons from runaway electrons. The Monte Carlo simulations take into account the effects of electron ionization, electron by electron (Møller), and electron by positron (Bhabha) scattering as well as the bremsstrahlung process and pair production, in the 250 eV to 100 GeV energy range. Our results indicate that the multiplication of electrons during the development of RREAs and under the influence of feedback are consistent with previous estimates. This is important to validate GEANT4 as a tool to model RREAs and feedback in homogeneous electric fields. We also determine the ratio of bremsstrahlung photons to energetic electrons Nγ /Ne . We then show that the ratio has a dependence on the electric field, which can be expressed by the avalanche time τ(E) and the bremsstrahlung coefficient α(ε). In addition, we present comparisons of GEANT4 simulations performed with a "standard" and a "low-energy" physics list both validated in the 1 keV to 100 GeV energy range. This comparison shows that the choice of physics list used in GEANT4 simulations has a significant effect on the results.

  1. A modular Geant4 model of Leksell Gamma Knife Perfexion™

    NASA Astrophysics Data System (ADS)

    Pipek, J.; Novotný, J.; Novotný, J., Jr.; Kozubíková, P.

    2014-12-01

    This work presents a Monte Carlo model of Leksell Gamma Knife Perfexion as well as the main parameters of the dose distribution in the standard phantom obtained using this model. The model is developed in the Geant4 simulation toolkit in a modular way which enables its reuse in other Perfexion studies. Large phase space files were created, containing particles that are entering the inner machine cavity after being transported through the collimation system. All 14 output factors of the machine and effective output factors for both the 4 mm (0.830 ± 0.009) and 8 mm (0.921 ± 0.004) collimators were calculated. Dose profiles along the main axes are also included for each collimator size. All results are compared to the values obtained from the treatment planning system, from experiments, and from other Monte Carlo models.

  2. Geant4 models for simulation of hadron/ion nuclear interactions at moderate and low energies.

    NASA Astrophysics Data System (ADS)

    Ivantchenko, Anton; Ivanchenko, Vladimir; Quesada, Jose-Manuel; Wright, Dennis

    The Geant4 toolkit is intended for Monte Carlo simulation of particle transport in media. It was initially designed for High Energy Physics purposes such as experiments at the Large Hadron Collider (LHC) at CERN. The toolkit offers a set of models allowing effective simulation of cosmic ray interactions with different materials. For moderate and low energy hadron/ion interactions with nuclei there are a number of competitive models: Binary and Bertini intra-nuclear cascade models, quantum molecular dynamic model (QMD), INCL/ABLA cascade model, and Chiral Invariant Phase Space Decay model (CHIPS). We report the status of these models for the recent version of Geant4 (release 9.3, December 2009). The Bertini cascade in-ternal cross sections were upgraded. The native Geant4 precompound and deexcitation models were used in the Binary cascade and QMD. They were significantly improved including emis-sion of light fragments, the Fermi break-up model, the General Evaporation Model (GEM), the multi-fragmentation model, and the fission model. Comparisons between model predictions and data for thin target experiments for neutron, proton, light ions, and isotope production are presented and discussed. The focus of these validations is concentrated on target materials important for space missions.

  3. Microdosimetry of electrons in liquid water using the low-energy models of Geant4

    NASA Astrophysics Data System (ADS)

    Kyriakou, I.; Emfietzoglou, D.; Ivanchenko, V.; Bordage, M. C.; Guatelli, S.; Lazarakis, P.; Tran, H. N.; Incerti, S.

    2017-07-01

    The biological effects of ionizing radiation at the cellular level are frequently studied using the well-known formalism of microdosimetry, which provides a quantitative description of the stochastic aspects of energy deposition in irradiated media. Energy deposition can be simulated using Monte Carlo codes, some adopting a computationally efficient condensed-history approach, while others follow a more detailed track-structure approach. In this work, we present the simulation of microdosimetry spectra and related quantities (frequency-mean and dose-mean lineal energies) for incident monoenergetic electrons (50 eV-10 keV) in spheres of liquid water with dimensions comparable to the size of biological targets: base pairs (2 nm diameter), nucleosomes (10 nm), chromatin fibres (30 nm) and chromosomes (300 nm). Simulations are performed using the condensed-history low-energy physics models ("Livermore" and "Penelope") and the track-structure Geant4-DNA physics models, available in the Geant4 Monte Carlo simulation toolkit. The spectra are compared and the influence of simulation parameters and different physics models, with emphasis on recent developments, is discussed, underlining the suitability of Geant4-DNA models for microdosimetry simulations. It is further shown that with an appropriate choice of simulation parameters, condensed-history transport may yield reasonable results for sphere sizes as small as a few tens of a nanometer.

  4. GODDeSS: a Geant4 extension for easy modelling of optical detector components

    NASA Astrophysics Data System (ADS)

    Dietz-Laursonn, E.; Hebbeker, T.; Künsken, A.; Merschmeyer, M.; Nieswand, S.; Niggemann, T.

    2017-04-01

    Scintillator- and fibre-based particle detectors with SiPM readout are an indispensable tool in high-energy particle physics, medical physics and other fields of application. For designing and understanding these detectors, very detailed simulations are necessary, which require an accurate modelling of the optical physics (optics, scintillation, wavelength-shifting effects, ... ), of the optical material properties, and of the geometry. To allow for a reliable usage also by less experienced users, the necessary complexity and flexibility of a suitable simulation framework must not lead to an increasing danger of user mistakes. Additionally, the required effort for creating or modifying a detailed simulation has to be minimised in order to allow for the fast creation of flexible simulation setups. These challenges have been addressed by developing GODDeSS (Geant4 Objects for Detailed Detectors with Scintillators and SiPMs). It is an extension of the particle-physics simulation tool Geant4 and allows for the easy simulation of optical detector components, especially combinations of scintillators, optical fibres, and photodetectors. GODDeSS enables the user to create extensive setups for Geant4 simulations with a few lines of source code. At the same time, GODDeSS helps to avoid typical user mistakes. This paper introduces the basic concepts of the GODDeSS framework, its object classes, and its functionality. Furthermore, test measurements with prototype modules will be presented, which were performed to validate simulation results of the GODDeSS framework.

  5. The impact of new Geant4-DNA cross section models on electron track structure simulations in liquid water

    SciTech Connect

    Kyriakou, I.; Šefl, M.; Nourry, V.; Incerti, S.

    2016-05-21

    The most recent release of the open source and general purpose Geant4 Monte Carlo simulation toolkit (Geant4 10.2 release) contains a new set of physics models in the Geant4-DNA extension for improving the modelling of low-energy electron transport in liquid water (<10 keV). This includes updated electron cross sections for excitation, ionization, and elastic scattering. In the present work, the impact of these developments to track-structure calculations is examined for providing the first comprehensive comparison against the default physics models of Geant4-DNA. Significant differences with the default models are found for the average path length and penetration distance, as well as for dose-point-kernels for electron energies below a few hundred eV. On the other hand, self-irradiation absorbed fractions for tissue-like volumes and low-energy electron sources (including some Auger emitters) reveal rather small differences (up to 15%) between these new and default Geant4-DNA models. The above findings indicate that the impact of the new developments will mainly affect those applications where the spatial pattern of interactions and energy deposition of very-low energy electrons play an important role such as, for example, the modelling of the chemical and biophysical stage of radiation damage to cells.

  6. Coupling of Geant4-DNA physics models into the GATE Monte Carlo platform: Evaluation of radiation-induced damage for clinical and preclinical radiation therapy beams

    NASA Astrophysics Data System (ADS)

    Pham, Q. T.; Anne, A.; Bony, M.; Delage, E.; Donnarieix, D.; Dufaure, A.; Gautier, M.; Lee, S. B.; Micheau, P.; Montarou, G.; Perrot, Y.; Shin, J. I.; Incerti, S.; Maigne, L.

    2015-06-01

    The GATE Monte Carlo simulation platform based on the Geant4 toolkit is in constant improvement for dosimetric calculations. In this paper, we present the integration of Geant4-DNA processes into the GATE 7.0 platform in the objective to perform multi-scale simulations (from macroscopic to nanometer scale). We simulated three types of clinical and preclinical beams: a 6 MeV electron clinical beam, a X-ray irradiator beam and a clinical proton beam for which we validated depth dose distributions against measurements in water. Frequencies of energy depositions and DNA damage were evaluated using a specific algorithm in charge of allocating energy depositions to atoms constituting DNA molecules represented by their PDB (Protein Data Bank) description.

  7. Comparison of electromagnetic and hadronic models generated using Geant 4 with antiproton dose measured in CERN.

    PubMed

    Tavakoli, Mohammad Bagher; Reiazi, Reza; Mohammadi, Mohammad Mehdi; Jabbari, Keyvan

    2015-01-01

    After proposing the idea of antiproton cancer treatment in 1984 many experiments were launched to investigate different aspects of physical and radiobiological properties of antiproton, which came from its annihilation reactions. One of these experiments has been done at the European Organization for Nuclear Research known as CERN using the antiproton decelerator. The ultimate goal of this experiment was to assess the dosimetric and radiobiological properties of beams of antiprotons in order to estimate the suitability of antiprotons for radiotherapy. One difficulty on this way was the unavailability of antiproton beam in CERN for a long time, so the verification of Monte Carlo codes to simulate antiproton depth dose could be useful. Among available simulation codes, Geant4 provides acceptable flexibility and extensibility, which progressively lead to the development of novel Geant4 applications in research domains, especially modeling the biological effects of ionizing radiation at the sub-cellular scale. In this study, the depth dose corresponding to CERN antiproton beam energy by Geant4 recruiting all the standard physics lists currently available and benchmarked for other use cases were calculated. Overall, none of the standard physics lists was able to draw the antiproton percentage depth dose. Although, with some models our results were promising, the Bragg peak level remained as the point of concern for our study. It is concluded that the Bertini model with high precision neutron tracking (QGSP_BERT_HP) is the best to match the experimental data though it is also the slowest model to simulate events among the physics lists.

  8. Comparison of electromagnetic and hadronic models generated using Geant 4 with antiproton dose measured in CERN

    PubMed Central

    Tavakoli, Mohammad Bagher; Reiazi, Reza; Mohammadi, Mohammad Mehdi; Jabbari, Keyvan

    2015-01-01

    After proposing the idea of antiproton cancer treatment in 1984 many experiments were launched to investigate different aspects of physical and radiobiological properties of antiproton, which came from its annihilation reactions. One of these experiments has been done at the European Organization for Nuclear Research known as CERN using the antiproton decelerator. The ultimate goal of this experiment was to assess the dosimetric and radiobiological properties of beams of antiprotons in order to estimate the suitability of antiprotons for radiotherapy. One difficulty on this way was the unavailability of antiproton beam in CERN for a long time, so the verification of Monte Carlo codes to simulate antiproton depth dose could be useful. Among available simulation codes, Geant4 provides acceptable flexibility and extensibility, which progressively lead to the development of novel Geant4 applications in research domains, especially modeling the biological effects of ionizing radiation at the sub-cellular scale. In this study, the depth dose corresponding to CERN antiproton beam energy by Geant4 recruiting all the standard physics lists currently available and benchmarked for other use cases were calculated. Overall, none of the standard physics lists was able to draw the antiproton percentage depth dose. Although, with some models our results were promising, the Bragg peak level remained as the point of concern for our study. It is concluded that the Bertini model with high precision neutron tracking (QGSP_BERT_HP) is the best to match the experimental data though it is also the slowest model to simulate events among the physics lists. PMID:26170558

  9. CHIPS_TPT models for exclusive Geant4 simulation of neutron-nuclear reactions at low energies

    NASA Astrophysics Data System (ADS)

    Kosov, Mikhail V.; Kudinov, Ilya V.; Savin, Dmitry I.

    2014-03-01

    A novel TPT code (Toolkit for Particle Transport), which is included in CHIPS_TPT physics list for Geant4 simulations, is briefly overviewed. Underlying concept of exclusive modelling is introduced and its beneficial features are illustrated with several examples. Widely used neutron Monte Carlo codes, MCNP and Geant4/HP, are based on inclusive algorithms that independently model neutron state change and secondary particles production while tracking. The exclusive approach implemented in TPT overcomes this unphysical separation and makes it possible to allow for kinematic restrictions as well as correlated emission of gamma-rays and secondaries.

  10. Evaluation of proton inelastic reaction models in Geant4 for prompt gamma production during proton radiotherapy

    NASA Astrophysics Data System (ADS)

    Jeyasugiththan, Jeyasingam; Peterson, Stephen W.

    2015-10-01

    During proton beam radiotherapy, discrete secondary prompt gamma rays are induced by inelastic nuclear reactions between protons and nuclei in the human body. In recent years, the Geant4 Monte Carlo toolkit has played an important role in the development of a device for real time dose range verification purposes using prompt gamma radiation. Unfortunately the default physics models in Geant4 do not reliably replicate the measured prompt gamma emission. Determining a suitable physics model for low energy proton inelastic interactions will boost the accuracy of prompt gamma simulations. Among the built-in physics models, we found that the precompound model with a modified initial exciton state of 2 (1 particle, 1 hole) produced more accurate discrete gamma lines from the most important elements found within the body such as 16O, 12C and 14N when comparing them with the available gamma production cross section data. Using the modified physics model, we investigated the prompt gamma spectra produced in a water phantom by a 200 MeV pencil beam of protons. The spectra were attained using a LaBr3 detector with a time-of-flight (TOF) window and BGO active shield to reduce the secondary neutron and gamma background. The simulations show that a 2 ns TOF window could reduce 99% of the secondary neutron flux hitting the detector. The results show that using both timing and active shielding can remove up to 85% of the background radiation which includes a 33% reduction by BGO subtraction.

  11. Evaluation of proton inelastic reaction models in Geant4 for prompt gamma production during proton radiotherapy.

    PubMed

    Jeyasugiththan, Jeyasingam; Peterson, Stephen W

    2015-10-07

    During proton beam radiotherapy, discrete secondary prompt gamma rays are induced by inelastic nuclear reactions between protons and nuclei in the human body. In recent years, the Geant4 Monte Carlo toolkit has played an important role in the development of a device for real time dose range verification purposes using prompt gamma radiation. Unfortunately the default physics models in Geant4 do not reliably replicate the measured prompt gamma emission. Determining a suitable physics model for low energy proton inelastic interactions will boost the accuracy of prompt gamma simulations. Among the built-in physics models, we found that the precompound model with a modified initial exciton state of 2 (1 particle, 1 hole) produced more accurate discrete gamma lines from the most important elements found within the body such as 16O, 12C and 14N when comparing them with the available gamma production cross section data. Using the modified physics model, we investigated the prompt gamma spectra produced in a water phantom by a 200 MeV pencil beam of protons. The spectra were attained using a LaBr3 detector with a time-of-flight (TOF) window and BGO active shield to reduce the secondary neutron and gamma background. The simulations show that a 2 ns TOF window could reduce 99% of the secondary neutron flux hitting the detector. The results show that using both timing and active shielding can remove up to 85% of the background radiation which includes a 33% reduction by BGO subtraction.

  12. Evaluation on Geant4 Hadronic Models for Pion Minus, Pion Plus and Neutron Particles as Major Antiproton Annihilation Products

    PubMed Central

    Tavakoli, Mohammad Bagher; Mohammadi, Mohammad Mehdi; Reiazi, Reza; Jabbari, Keyvan

    2015-01-01

    Geant4 is an open source simulation toolkit based on C++, which its advantages progressively lead to applications in research domains especially modeling the biological effects of ionizing radiation at the sub-cellular scale. However, it was shown that Geant4 does not give a reasonable result in the prediction of antiproton dose especially in Bragg peak. One of the reasons could be lack of reliable physic model to predict the final states of annihilation products like pions. Considering the fact that most of the antiproton deposited dose is resulted from high-LET nuclear fragments following pion interaction in surrounding nucleons, we reproduced depth dose curves of most probable energy range of pions and neutron particle using Geant4. We consider this work one of the steps to understand the origin of the error and finally verification of Geant4 for antiproton tracking. Geant4 toolkit version 9.4.6.p01 and Fluka version 2006.3 were used to reproduce the depth dose curves of 220 MeV pions (both negative and positive) and 70 MeV neutrons. The geometry applied in the simulations consist a 20 × 20 × 20 cm3 water tank, similar to that used in CERN for antiproton relative dose measurements. Different physic lists including Quark-Gluon String Precompound (QGSP)_Binary Cascade (BIC)_HP, the recommended setting for hadron therapy, were used. In the case of pions, Geant4 resulted in at least 5% dose discrepancy between different physic lists at depth close to the entrance point. Even up to 15% discrepancy was found in some cases like QBBC compared to QGSP_BIC_HP. A significant difference was observed in dose profiles of different Geant4 physic list at small depths for a beam of pions. In the case of neutrons, large dose discrepancy was observed when LHEP or LHEP_EMV lists were applied. The magnitude of this dose discrepancy could be even 50% greater than the dose calculated by LHEP (or LHEP_EMV) at larger depths. We found that effect different Geant4 physic list in

  13. CAD-based Automatic Modeling Method for Geant4 geometry model Through MCAM

    NASA Astrophysics Data System (ADS)

    Wang, Dong; Nie, Fanzhi; Wang, Guozhong; Long, Pengcheng; LV, Zhongliang; LV, Zhongliang

    2014-06-01

    Geant4 is a widely used Monte Carlo transport simulation package. Before calculating using Geant4, the calculation model need be established which could be described by using Geometry Description Markup Language (GDML) or C++ language. However, it is time-consuming and error-prone to manually describe the models by GDML. Automatic modeling methods have been developed recently, but there are some problem existed in most of present modeling programs, specially some of them were not accurate or adapted to specifically CAD format. To convert the GDML format models to CAD format accurately, a Geant4 Computer Aided Design (CAD) based modeling method was developed for automatically converting complex CAD geometry model into GDML geometry model. The essence of this method was dealing with CAD model represented with boundary representation (B-REP) and GDML model represented with constructive solid geometry (CSG). At first, CAD model was decomposed to several simple solids which had only one close shell. And then the simple solid was decomposed to convex shell set. Then corresponding GDML convex basic solids were generated by the boundary surfaces getting from the topological characteristic of a convex shell. After the generation of these solids, GDML model was accomplished with series boolean operations. This method was adopted in CAD/Image-based Automatic Modeling Program for Neutronics & Radiation Transport (MCAM), and tested with several models including the examples in Geant4 install package. The results showed that this method could convert standard CAD model accurately, and can be used for Geant4 automatic modeling.

  14. A Roadmap For Geant4

    NASA Astrophysics Data System (ADS)

    Asai, Makoto

    2012-12-01

    The Geant4 simulation toolkit is now in the 14th year of its production phase. Geant4 is the choice of most current and near future high energy physics experiments as their simulation engine, and it is also widely used in astrophysics, space engineering, medicine and industrial application domains. Geant4 is a “living” code under continuous development; improvement of physics quality and computational speed is still a priority for Geant4. It is evolving and being enriched with new functionalities. On the other hand, the simulation paradigm that prevailed during the foundation of Geant4 is now being rethought because of new technologies in both computer hardware and software. The Geant4 Collaboration has identified many options and possibilities. Geant4 has accommodated some of these by providing a multi-threading prototype based on event-level parallelism. In this article we discuss the past, present and future of the Geant4 toolkit.

  15. Accuracy of the photon and electron physics in GEANT4 for radiotherapy applications.

    PubMed

    Poon, Emily; Verhaegen, Frank

    2005-06-01

    This work involves a validation of the photon and electron transport of the GEANT4 particle simulation toolkit for radiotherapy physics applications. We examine the cross sections and sampling algorithms of the three electromagnetic physics models in version 4.6.1 of the toolkit: Standard, Low-energy, and Penelope. The depth dose distributions in water for incident monoenergetic and clinical beams are compared to the EGSNRC results. In photon beam simulations, all three models agree with EGSNRC to within 2%, except for the buildup region. Larger deviations are found for incident electron beams, and the differences are affected by user-imposed electron step limitations. Particle distributions through thin layers of clinical target materials, and perturbation effects near high-Z and low-Z interfaces are also investigated. The electron step size artifacts observed in our studies indicate potential problems with the condensed history algorithm. A careful selection of physics processes and transport parameters is needed for optimum efficiency and accuracy.

  16. Accuracy of the photon and electron physics in GEANT4 for radiotherapy applications.

    PubMed

    Poon, Emily; Verhaegen, Frank

    2005-06-01

    This work involves a validation of the photon and electron transport of the GEANT4 particle simulation toolkit for radiotherapy physics applications. We examine the cross sections and sampling algorithms of the three electromagnetic physics models in version 4.6.1 of the toolkit: Standard, Low-energy, and Penelope. The depth dose distributions in water for incident monoenergetic and clinical beams are compared to the EGSNRC results. In photon beam simulations, all three models agree with EGSNRC to within 2%, except for the buildup region. Larger deviations are found for incident electron beams, and the differences are affected by user-imposed electron step limitations. Particle distributions through thin layers of clinical target materials, and perturbation effects near high-Z and low-Z interfaces are also investigated. The electron step size artifacts observed in our studies indicate potential problems with the condensed history algorithm. A careful selection of physics processes and transport parameters is needed for optimum efficiency and accuracy. © 2005 American Association of Physicists in Medicine.

  17. The GEANT4 Visualisation System

    SciTech Connect

    Allison, J.; Asai, M.; Barrand, G.; Donszelmann, M.; Minamimoto, K.; Tanaka, S.; Tcherniaev, E.; Tinslay, J.; /SLAC

    2007-11-02

    The Geant4 Visualization System is a multi-driver graphics system designed to serve the Geant4 Simulation Toolkit. It is aimed at the visualization of Geant4 data, primarily detector descriptions and simulated particle trajectories and hits. It can handle a variety of graphical technologies simultaneously and interchangeably, allowing the user to choose the visual representation most appropriate to requirements. It conforms to the low-level Geant4 abstract graphical user interfaces and introduces new abstract classes from which the various drivers are derived and that can be straightforwardly extended, for example, by the addition of a new driver. It makes use of an extendable class library of models and filters for data representation and selection. The Geant4 Visualization System supports a rich set of interactive commands based on the Geant4 command system. It is included in the Geant4 code distribution and maintained and documented like other components of Geant4.

  18. The Geant4 Bertini Cascade

    SciTech Connect

    Wright, D. H.; Kelsey, M. H.

    2015-12-01

    One of the medium energy hadron–nucleus interaction models in the Geant4 simulation toolkit is based partly on the Bertini intranuclear cascade model. Since its initial appearance in the toolkit, this model has been largely re-written in order to extend its physics capabilities and to reduce its memory footprint. Physics improvements include extensions in applicable energy range and incident particle types, and improved hadron–nucleon cross-sections and angular distributions. Interfaces have also been developed which allow the model to be coupled with other Geant4 models at lower and higher energies. The inevitable speed reductions due to enhanced physics have been mitigated by memory and CPU efficiency improvements. Details of these improvements, along with selected comparisons of the model to data, are discussed.

  19. Geant4-DNA simulation of electron slowing-down spectra in liquid water

    NASA Astrophysics Data System (ADS)

    Incerti, S.; Kyriakou, I.; Tran, H. N.

    2017-04-01

    This work presents the simulation of monoenergetic electron slowing-down spectra in liquid water by the Geant4-DNA extension of the Geant4 Monte Carlo toolkit (release 10.2p01). These spectra are simulated for several incident energies using the most recent Geant4-DNA physics models, and they are compared to literature data. The influence of Auger electron production is discussed. For the first time, a dedicated Geant4-DNA example allowing such simulations is described and is provided to Geant4 users, allowing further verification of Geant4-DNA track structure simulation capabilities.

  20. Recent developments in Geant4

    DOE PAGES

    Allison, J.; Amako, K.; Apostolakis, J.; ...

    2016-07-01

    Geant4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. In conclusion, the adaptation of Geant4 to multithreading, advances in physics, detector modeling and visualization, extensions tomore » the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.« less

  1. Recent developments in Geant4

    SciTech Connect

    Allison, J.; Amako, K.; Apostolakis, J.; Arce, P.; Asai, M.; Aso, T.; Bagli, E.; Bagulya, A.; Banerjee, S.; Barrand, G.; Beck, B. R.; Bogdanov, A. G.; Brandt, D.; Brown, J. M. C.; Burkhardt, H.; Canal, Ph.; Cano-Ott, D.; Chauvie, S.; Cho, K.; Cirrone, G. A. P.; Cooperman, G.; Cortés-Giraldo, M. A.; Cosmo, G.; Cuttone, G.; Depaola, G.; Desorgher, L.; Dong, X.; Dotti, A.; Elvira, V. D.; Folger, G.; Francis, Z.; Galoyan, A.; Garnier, L.; Gayer, M.; Genser, K. L.; Grichine, V. M.; Guatelli, S.; Guèye, P.; Gumplinger, P.; Howard, A. S.; Hřivnáčová, I.; Hwang, S.; Incerti, S.; Ivanchenko, A.; Ivanchenko, V. N.; Jones, F. W.; Jun, S. Y.; Kaitaniemi, P.; Karakatsanis, N.; Karamitrosi, M.; Kelsey, M.; Kimura, A.; Koi, T.; Kurashige, H.; Lechner, A.; Lee, S. B.; Longo, F.; Maire, M.; Mancusi, D.; Mantero, A.; Mendoza, E.; Morgan, B.; Murakami, K.; Nikitina, T.; Pandola, L.; Paprocki, P.; Perl, J.; Petrović, I.; Pia, M. G.; Pokorski, W.; Quesada, J. M.; Raine, M.; Reis, M. A.; Ribon, A.; Ristić Fira, A.; Romano, F.; Russo, G.; Santin, G.; Sasaki, T.; Sawkey, D.; Shin, J. I.; Strakovsky, I. I.; Taborda, A.; Tanaka, S.; Tomé, B.; Toshito, T.; Tran, H. N.; Truscott, P. R.; Urban, L.; Uzhinsky, V.; Verbeke, J. M.; Verderi, M.; Wendt, B. L.; Wenzel, H.; Wright, D. H.; Wright, D. M.; Yamashita, T.; Yarba, J.; Yoshida, H.

    2016-07-01

    Geant4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. In conclusion, the adaptation of Geant4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.

  2. Recent developments in GEANT4

    NASA Astrophysics Data System (ADS)

    Allison, J.; Amako, K.; Apostolakis, J.; Arce, P.; Asai, M.; Aso, T.; Bagli, E.; Bagulya, A.; Banerjee, S.; Barrand, G.; Beck, B. R.; Bogdanov, A. G.; Brandt, D.; Brown, J. M. C.; Burkhardt, H.; Canal, Ph.; Cano-Ott, D.; Chauvie, S.; Cho, K.; Cirrone, G. A. P.; Cooperman, G.; Cortés-Giraldo, M. A.; Cosmo, G.; Cuttone, G.; Depaola, G.; Desorgher, L.; Dong, X.; Dotti, A.; Elvira, V. D.; Folger, G.; Francis, Z.; Galoyan, A.; Garnier, L.; Gayer, M.; Genser, K. L.; Grichine, V. M.; Guatelli, S.; Guèye, P.; Gumplinger, P.; Howard, A. S.; Hřivnáčová, I.; Hwang, S.; Incerti, S.; Ivanchenko, A.; Ivanchenko, V. N.; Jones, F. W.; Jun, S. Y.; Kaitaniemi, P.; Karakatsanis, N.; Karamitrosi, M.; Kelsey, M.; Kimura, A.; Koi, T.; Kurashige, H.; Lechner, A.; Lee, S. B.; Longo, F.; Maire, M.; Mancusi, D.; Mantero, A.; Mendoza, E.; Morgan, B.; Murakami, K.; Nikitina, T.; Pandola, L.; Paprocki, P.; Perl, J.; Petrović, I.; Pia, M. G.; Pokorski, W.; Quesada, J. M.; Raine, M.; Reis, M. A.; Ribon, A.; Ristić Fira, A.; Romano, F.; Russo, G.; Santin, G.; Sasaki, T.; Sawkey, D.; Shin, J. I.; Strakovsky, I. I.; Taborda, A.; Tanaka, S.; Tomé, B.; Toshito, T.; Tran, H. N.; Truscott, P. R.; Urban, L.; Uzhinsky, V.; Verbeke, J. M.; Verderi, M.; Wendt, B. L.; Wenzel, H.; Wright, D. H.; Wright, D. M.; Yamashita, T.; Yarba, J.; Yoshida, H.

    2016-11-01

    GEANT4 is a software toolkit for the simulation of the passage of particles through matter. It is used by a large number of experiments and projects in a variety of application domains, including high energy physics, astrophysics and space science, medical physics and radiation protection. Over the past several years, major changes have been made to the toolkit in order to accommodate the needs of these user communities, and to efficiently exploit the growth of computing power made available by advances in technology. The adaptation of GEANT4 to multithreading, advances in physics, detector modeling and visualization, extensions to the toolkit, including biasing and reverse Monte Carlo, and tools for physics and release validation are discussed here.

  3. Technical Note: Improvements in GEANT4 energy-loss model and the effect on low-energy electron transport in liquid water

    SciTech Connect

    Kyriakou, I.; Incerti, S.

    2015-07-15

    Purpose: The GEANT4-DNA physics models are upgraded by a more accurate set of electron cross sections for ionization and excitation in liquid water. The impact of the new developments on low-energy electron transport simulations by the GEANT4 Monte Carlo toolkit is examined for improving its performance in dosimetry applications at the subcellular and nanometer level. Methods: The authors provide an algorithm for an improved implementation of the Emfietzoglou model dielectric response function of liquid water used in the GEANT4-DNA existing model. The algorithm redistributes the imaginary part of the dielectric function to ensure a physically motivated behavior at the binding energies, while retaining all the advantages of the original formulation, e.g., the analytic properties and the fulfillment of the f-sum-rule. In addition, refinements in the exchange and perturbation corrections to the Born approximation used in the GEANT4-DNA existing model are also made. Results: The new ionization and excitation cross sections are significantly different from those of the GEANT4-DNA existing model. In particular, excitations are strongly enhanced relative to ionizations, resulting in higher W-values and less diffusive dose-point-kernels at sub-keV electron energies. Conclusions: An improved energy-loss model for the excitation and ionization of liquid water by low-energy electrons has been implemented in GEANT4-DNA. The suspiciously low W-values and the unphysical long tail in the dose-point-kernel have been corrected owing to a different partitioning of the dielectric function.

  4. Simulation and modeling for the stand-off radiation detection system (SORDS) using GEANT4

    SciTech Connect

    Hoover, Andrew S; Wallace, Mark; Galassi, Mark; Mocko, Michal; Palmer, David; Schultz, Larry; Tornga, Shawn

    2009-01-01

    A Stand-Off Radiation Detection System (SORDS) is being developed through a joint effort by Raytheon, Los Alamos National Laboratory, Bubble Technology Industries, Radiation Monitoring Devices, and the Massachusetts Institute of Technology, for the Domestic Nuclear Detection Office (DNDO). The system is a mobile truck-based platform performing detection, imaging, and spectroscopic identification of gamma-ray sources. A Tri-Modal Imaging (TMI) approach combines active-mask coded aperture imaging, Compton imaging, and shadow imaging techniques. Monte Carlo simulation and modeling using the GEANT4 toolkit was used to generate realistic data for the development of imaging algorithms and associated software code.

  5. In-beam quality assurance using induced β+ activity in hadrontherapy: a preliminary physical requirements study using Geant4

    NASA Astrophysics Data System (ADS)

    Lestand, L.; Montarou, G.; Force, P.; Pauna, N.

    2012-10-01

    Light and heavy ions particle therapy, mainly by means of protons and carbon ions, represents an advantageous treatment modality for deep-seated and/or radioresistant tumours. An in-beam quality assurance principle is based on the detection of secondary particles induced by nuclear fragmentations between projectile and target nuclei. Three different strategies are currently under investigation: prompt γ rays imaging, proton interaction vertex imaging and in-beam positron emission tomography. Geant4 simulations have been performed first in order to assess the accuracy of some hadronic models to reproduce experimental data. Two different kinds of data have been considered: β+-emitting isotopes and prompt γ-ray production rates. On the one hand simulations reproduce experimental β+ emitting isotopes production rates to an accuracy of 24%. Moreover simulated β+ emitting nuclei production rate as a function of depth reproduce well the peak-to-plateau ratio of experimental data. On the other hand by tuning the tolerance factor of the photon evaporation model available in Geant4, we reduce significantly prompt γ-ray production rates until a very good agreement is reached with experimental data. Then we have estimated the total amount of induced annihilation photons and prompt γ rays for a simple treatment plan of ∼1 physical Gy in a homogenous equivalent soft tissue tumour (6 cm depth, 4 cm radius and 2 cm wide). The average annihilation photons emitted during a 45 s irradiation in a 4 π solid angle are ∼2 × 106 annihilation photon pairs and 108 single prompt γ whose energy ranges from a few keV to 10 MeV.

  6. In-beam quality assurance using induced β(+) activity in hadrontherapy: a preliminary physical requirements study using Geant4.

    PubMed

    Lestand, L; Montarou, G; Force, P; Pauna, N

    2012-10-21

    Light and heavy ions particle therapy, mainly by means of protons and carbon ions, represents an advantageous treatment modality for deep-seated and/or radioresistant tumours. An in-beam quality assurance principle is based on the detection of secondary particles induced by nuclear fragmentations between projectile and target nuclei. Three different strategies are currently under investigation: prompt γ rays imaging, proton interaction vertex imaging and in-beam positron emission tomography. Geant4 simulations have been performed first in order to assess the accuracy of some hadronic models to reproduce experimental data. Two different kinds of data have been considered: β(+)-emitting isotopes and prompt γ-ray production rates. On the one hand simulations reproduce experimental β(+) emitting isotopes production rates to an accuracy of 24%. Moreover simulated β(+) emitting nuclei production rate as a function of depth reproduce well the peak-to-plateau ratio of experimental data. On the other hand by tuning the tolerance factor of the photon evaporation model available in Geant4, we reduce significantly prompt γ-ray production rates until a very good agreement is reached with experimental data. Then we have estimated the total amount of induced annihilation photons and prompt γ rays for a simple treatment plan of ∼1 physical Gy in a homogenous equivalent soft tissue tumour (6 cm depth, 4 cm radius and 2 cm wide). The average annihilation photons emitted during a 45 s irradiation in a 4 π solid angle are ∼2 × 10(6) annihilation photon pairs and 10(8) single prompt γ whose energy ranges from a few keV to 10 MeV.

  7. Carbon fragmentation measurements and validation of the Geant4 nuclear reaction models for hadrontherapy.

    PubMed

    De Napoli, M; Agodi, C; Battistoni, G; Blancato, A A; Cirrone, G A P; Cuttone, G; Giacoppo, F; Morone, M C; Nicolosi, D; Pandola, L; Patera, V; Raciti, G; Rapisarda, E; Romano, F; Sardina, D; Sarti, A; Sciubba, A; Scuderi, V; Sfienti, C; Tropea, S

    2012-11-21

    Nuclear fragmentation measurements are necessary when using heavy-ion beams in hadrontherapy to predict the effects of the ion nuclear interactions within the human body. Moreover, they are also fundamental to validate and improve the Monte Carlo codes for their use in planning tumor treatments. Nowadays, a very limited set of carbon fragmentation cross sections are being measured, and in particular, to our knowledge, no double-differential fragmentation cross sections at intermediate energies are available in the literature. In this work, we have measured the double-differential cross sections and the angular distributions of the secondary fragments produced in the (12)C fragmentation at 62 A MeV on a thin carbon target. The experimental data have been used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before. In particular, we have compared the experimental data with the predictions of two Geant4 nuclear reaction models: the Binary Light Ions Cascade and the Quantum Molecular Dynamic. From the comparison, it has been observed that the Binary Light Ions Cascade approximates the angular distributions of the fragment production cross sections better than the Quantum Molecular Dynamic model. However, the discrepancies observed between the experimental data and the Monte Carlo simulations lead to the conclusion that the prediction capability of both models needs to be improved at intermediate energies.

  8. Carbon fragmentation measurements and validation of the Geant4 nuclear reaction models for hadrontherapy

    NASA Astrophysics Data System (ADS)

    De Napoli, M.; Agodi, C.; Battistoni, G.; Blancato, A. A.; Cirrone, G. A. P.; Cuttone, G.; Giacoppo, F.; Morone, M. C.; Nicolosi, D.; Pandola, L.; Patera, V.; Raciti, G.; Rapisarda, E.; Romano, F.; Sardina, D.; Sarti, A.; Sciubba, A.; Scuderi, V.; Sfienti, C.; Tropea, S.

    2012-11-01

    Nuclear fragmentation measurements are necessary when using heavy-ion beams in hadrontherapy to predict the effects of the ion nuclear interactions within the human body. Moreover, they are also fundamental to validate and improve the Monte Carlo codes for their use in planning tumor treatments. Nowadays, a very limited set of carbon fragmentation cross sections are being measured, and in particular, to our knowledge, no double-differential fragmentation cross sections at intermediate energies are available in the literature. In this work, we have measured the double-differential cross sections and the angular distributions of the secondary fragments produced in the 12C fragmentation at 62 A MeV on a thin carbon target. The experimental data have been used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before. In particular, we have compared the experimental data with the predictions of two Geant4 nuclear reaction models: the Binary Light Ions Cascade and the Quantum Molecular Dynamic. From the comparison, it has been observed that the Binary Light Ions Cascade approximates the angular distributions of the fragment production cross sections better than the Quantum Molecular Dynamic model. However, the discrepancies observed between the experimental data and the Monte Carlo simulations lead to the conclusion that the prediction capability of both models needs to be improved at intermediate energies.

  9. Validation of a Geant4 model of the X-ray fluorescence microprobe at the Australian Synchrotron.

    PubMed

    Dimmock, Matthew Richard; de Jonge, Martin Daly; Howard, Daryl Lloyd; James, Simon Alexander; Kirkham, Robin; Paganin, David Maurice; Paterson, David John; Ruben, Gary; Ryan, Chris Gregory; Brown, Jeremy Michael Cooney

    2015-03-01

    A Geant4 Monte Carlo simulation of the X-ray fluorescence microprobe (XFM) end-station at the Australian Synchrotron has been developed. The simulation is required for optimization of the scan configuration and reconstruction algorithms. As part of the simulation process, a Gaussian beam model was developed. Experimental validation of this simulation has tested the efficacy for use of the low-energy physics models in Geant4 for this synchrotron-based technique. The observed spectral distributions calculated in the 384 pixel Maia detector, positioned in the standard back-scatter configuration, were compared with those obtained from experiments performed at three incident X-ray beam energies: 18.5, 11.0 and 6.8 keV. The reduced χ-squared (\\chi^{2}_{\\rm{red}}) was calculated for the scatter and fluorescence regions of the spectra and demonstrates that the simulations successfully reproduce the scatter distributions. Discrepancies were shown to occur in the multiple-scatter tail of the Compton continuum. The model was shown to be particularly sensitive to the impurities present in the beryllium window of the Maia detector and their concentrations were optimized to improve the \\chi^{2}_{\\rm{red}} parametrization in the low-energy fluorescence regions of the spectra.

  10. Energy deposition in small-scale targets of liquid water using the very low energy electromagnetic physics processes of the Geant4 toolkit

    NASA Astrophysics Data System (ADS)

    Incerti, S.; Champion, C.; Tran, H. N.; Karamitros, M.; Bernal, M.; Francis, Z.; Ivanchenko, V.; Mantero, A.; Members of Geant4-DNA Collaboration

    2013-07-01

    In the perspective of building an open source simulation platform dedicated to the modelling of early biological molecular damages due to ionising radiation at the DNA scale, the general-purpose Geant4 Monte Carlo simulation toolkit has been recently extended with specific very low energy electromagnetic physics processes for liquid water medium. These processes - also called “Geant4-DNA” processes - simulate the physical interactions induced by electrons, hydrogen and helium atoms of different charge states. The present work reports on the energy deposit distributions obtained for incident electrons, protons and alpha particles in nanometre-size volumes comparable to those present in the genetic material of mammalian cells. The frequency distributions of the energy deposition obtained for three typical geometries of nanometre-size cylindrical targets placed in a spherical phantom are found to be in reasonable agreement with prior works. Furthermore, we present a combination of the Geant4-DNA processes with a simplified geometrical model of a cellular nucleus allowing the evaluation of energy deposits in volumes of biological interest.

  11. Geant4.10 simulation of geometric model for metaphase chromosome

    NASA Astrophysics Data System (ADS)

    Rafat-Motavalli, L.; Miri-Hakimabad, H.; Bakhtiyari, E.

    2016-04-01

    In this paper, a geometric model of metaphase chromosome is explained. The model is constructed according to the packing ratio and dimension of the structure from nucleosome up to chromosome. A B-DNA base pair is used to construct 200 base pairs of nucleosomes. Each chromatin fiber loop, which is the unit of repeat, has 49,200 bp. This geometry is entered in Geant4.10 Monte Carlo simulation toolkit and can be extended to the whole metaphase chromosomes and any application in which a DNA geometrical model is needed. The chromosome base pairs, chromosome length, and relative length of chromosomes are calculated. The calculated relative length is compared to the relative length of human chromosomes.

  12. Simulation loop between cad systems, GEANT-4 and GeoModel: Implementation and results

    NASA Astrophysics Data System (ADS)

    Sharmazanashvili, A.; Tsutskiridze, Niko

    2016-09-01

    Compare analysis of simulation and as-built geometry descriptions of detector is important field of study for data_vs_Monte-Carlo discrepancies. Shapes consistency and detalization is not important while adequateness of volumes and weights of detector components are essential for tracking. There are 2 main reasons of faults of geometry descriptions in simulation: (1) Difference between simulated and as-built geometry descriptions; (2) Internal inaccuracies of geometry transformations added by simulation software infrastructure itself. Georgian Engineering team developed hub on the base of CATIA platform and several tools enabling to read in CATIA different descriptions used by simulation packages, like XML->CATIA; VP1->CATIA; Geo-Model->CATIA; Geant4->CATIA. As a result it becomes possible to compare different descriptions with each other using the full power of CATIA and investigate both classes of reasons of faults of geometry descriptions. Paper represents results of case studies of ATLAS Coils and End-Cap toroid structures.

  13. Comparison of the neutron ambient dose equivalent and ambient absorbed dose calculations with different GEANT4 physics lists

    NASA Astrophysics Data System (ADS)

    Ribeiro, Rosane Moreira; Souza-Santos, Denison

    2017-10-01

    A comparison between neutron physics lists given by GEANT4, is made in the calculation of the ambient dose equivalent, and ambient absorbed dose, per fluence conversion coefficients (H* (10) / ϕ and D* (10) / ϕ) for neutrons in the range of 10-9 MeV to 15 MeV. Physics processes are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles. Results obtained for QBBC, QGSP_BERT, QGSP_BIC and Neutron High Precision physics lists are compared with values published in ICRP 74 and previously published articles. Neutron high precision physics lists showed the best results in the studied energy range.

  14. Geant4 Standard and Low Energy electromagnetic libraries

    NASA Astrophysics Data System (ADS)

    Ivanchenko, Vladimir; Incerti, Sebastien

    2017-04-01

    Geant4 is a Monte Carlo toolkit well established for large scale simulations for high energy physics, medicine, space science and other applications. Electromagnetic (EM) physics libraries are key components of these simulations. In this work we describe the Standard and Low Energy EM libraries available in Geant4 version 10.3 including descriptions of new models and interfaces relevant for dark matter searches and limits of applicability for these models.

  15. Geant4 - A Simulation Toolkit

    SciTech Connect

    Wright, Dennis H

    2002-08-09

    GEANT4 is a toolkit for simulating the passage of particles through matter. it includes a complete range of functionality including tracking, geometry, physics models and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250 eV and extending in others to the TeV energy range. it has been designed and constructed to expose the physics models utilized, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications. The toolkit is the result of a worldwide collaboration of physicists and software engineers. It has been created exploiting software engineering and object-oriented technology and implemented in the C++ programming language. It has been used in applications in particle physics, nuclear physics, accelerator design, space engineering and medical physics.

  16. Monte-Carlo modelling and verification of photoluminescence of Gd2O3:Eu scintillator by using the GEANT4 simulation code

    NASA Astrophysics Data System (ADS)

    Cho, Gyu-Seok; Kim, Kum-Bae; Choi, Sang-Hyoun; Song, Yong-Keun; Lee, Soon-Sung

    2017-01-01

    Recently, Monte Carlo methods have been used to optimize the design and modeling of radiation detectors. However, most Monte Carlo codes have a fixed and simple optical physics, and the effect of the signal readout devices is not considered because of the limitations of the geometry function. Therefore, the disadvantages of the codes prevent the modeling of the scintillator detector. The modeling of a comprehensive and extensive detector system has been reported to be feasible when the optical physics model of the GEomerty ANd Tracking 4 (GEANT 4) simulation code is used. In this study, we performed a Gd2O3:Eu scintillator modelling by using the GEANT4 simulation code and compared the results with the measurement data. To obtain the measurement data for the scintillator, we synthesized the Gd2O3:Eu scintillator by using solution combustion method and we evaluated the characteristics of the scintillator by using X-ray diffraction and photoluminescence. We imported the measured data into the GEANT4 code because GEANT4 cannot simulate a fluorescence phenomenon. The imported data were used as an energy distribution for optical photon generation based on the energy deposited in the scintillator. As a result of the simulation, a strong emission peak consistent with the measured data was observed at 611 nm, and the overall trends of the spectrum agreed with the measured data. This result is significant because the characteristics of the scintillator are equally implemented in the simulation, indicating a valuable improvement in the modeling of scintillator-based radiation detectors.

  17. Comparison of Geant4 multiple Coulomb scattering models with theory for radiotherapy protons

    NASA Astrophysics Data System (ADS)

    Makarova, Anastasia; Gottschalk, Bernard; Sauerwein, Wolfgang

    2017-08-01

    Usually, Monte Carlo models are validated against experimental data. However, models of multiple Coulomb scattering (MCS) in the Gaussian approximation are exceptional in that we have theories which are probably more accurate than the experiments which have, so far, been done to test them. In problems directly sensitive to the distribution of angles leaving the target, the relevant theory is the Molière/Fano/Hanson variant of Molière theory (Gottschalk et al 1993 Nucl. Instrum. Methods Phys. Res. B 74 467-90). For transverse spreading of the beam in the target itself, the theory of Preston and Koehler (Gottschalk (2012 arXiv:1204.4470)) holds. Therefore, in this paper we compare Geant4 simulations, using the Urban and Wentzel models of MCS, with theory rather than experiment, revealing trends which would otherwise be obscured by experimental scatter. For medium-energy (radiotherapy) protons, and low-Z (water-like) target materials, Wentzel appears to be better than Urban in simulating the distribution of outgoing angles. For beam spreading in the target itself, the two models are essentially equal.

  18. Modeling of x-ray fluorescence using MCNPX and Geant4

    SciTech Connect

    Rajasingam, Akshayan; Hoover, Andrew S; Fensin, Michael L; Tobin, Stephen J

    2009-01-01

    X-Ray Fluorescence (XRF) is one of thirteen non-destructive assay techniques being researched for the purpose of quantifying the Pu mass in used fuel assemblies. The modeling portion of this research will be conducted with the MCNPX transport code. The research presented here was undertaken to test the capability of MCNPX so that it can be used to benchmark measurements made at the ORNL and to give confidence in the application of MCNPX as a predictive tool of the expected capability of XRF in the context of used fuel assemblies. The main focus of this paper is a code-to-code comparison between MCNPX and Geant4 code. Since XRF in used fuel is driven by photon emission and beta decay of fission fragments, both terms were independently researched. Simple cases and used fuel cases were modeled for both source terms. In order to prepare for benchmarking to experiments, it was necessary to determine the relative significance of the various fission fragments for producing X-rays.

  19. Geant4-DNA: overview and recent developments

    NASA Astrophysics Data System (ADS)

    Štěpán, Václav

    Space travel and high altitude flights are inherently associated with prolonged exposure to cosmic and solar radiation. Understanding and simulation of radiation action on cellular and subcellular level contributes to precise assessment of the associated health risks and remains a challenge of today’s radiobiology research. The Geant4-DNA project (http://geant4-dna.org) aims at developing an experimentally validated simulation platform for modelling of the damage induced by ionizing radiation at DNA level. The platform is based on the Geant4 Monte Carlo simulation toolkit. This project extends specific functionalities of Geant4 in following areas: The step-by-step single scattering modelling of elementary physical interactions of electrons, protons, alpha particles and light ions with liquid water and DNA bases, for the so-called “physical” stage. The modelling of the “physico-chemical and chemical” stages corresponding to the production, the diffusion, the chemical reactions occurring between chemical species produced by water radiolysis, and to the radical attack on the biological targets. Physical and chemical stage simulations are combined with biological target models on several scales, from DNA double helix, through nucleosome, to chromatin segments and cell geometries. In addition, data mining clustering algorithms have been developed and optimised for the purpose of DNA damage scoring in simulated tracks. Experimental measurements on pBR322 plasmid DNA are being carried out in order to validate the Geant4-DNA models. The plasmid DNA has been irradiated in dry conditions by protons with energies from 100 keV to 30 MeV and in aqueous conditions, with and without scavengers, by 30 MeV protons, 290 MeV/u carbon and 500 MeV/u iron ions. Agarose gel electrophoresis combined with enzymatic treatment has been used to measure the resulting DNA damage. An overview of the developments undertaken by the Geant4-DNA collaboration including a description of

  20. Channeling efficiency dependence on bending radius and thermal vibration amplitude of the model for the channeling of high-energy particles in straight and bent crystals implemented in Geant4

    NASA Astrophysics Data System (ADS)

    Bagli, Enrico; Asai, Makoto; Dotti, Andrea; Guidi, Vincenzo; Verderi, Marc

    2015-07-01

    Monte Carlo simulations of the interaction of particles with matter are usually done with downloadable toolkits such as Geant4. A model suitable for the implementation into Geant4 for the interaction of high-energy particles in straight and bent crystals was developed and implemented. The model relies on the continuum potential approximation. The variation of the Geant4 model for the description of the orientational effect as a function of the physical parameters for the calculation of the interplanar potential is presented. The simulations are capable of reproducing the variation of the efficiency of channeling as a function of the thermal vibration amplitude and the bending radius of a bent Si strip. The study can be useful for the simulation of the channeling effect in experiments at GeV/c energies.

  1. GEANT4 and Secondary Particle Production

    NASA Technical Reports Server (NTRS)

    Patterson, Jeff

    2004-01-01

    GEANT 4 is a Monte Carlo tool set developed by the High Energy Physics Community (CERN, SLAC, etc) to perform simulations of complex particle detectors. GEANT4 is the ideal tool to study radiation transport and should be applied to space environments and the complex geometries of modern day spacecraft.

  2. GEANT4 and Secondary Particle Production

    NASA Technical Reports Server (NTRS)

    Patterson, Jeff

    2004-01-01

    GEANT 4 is a Monte Carlo tool set developed by the High Energy Physics Community (CERN, SLAC, etc) to perform simulations of complex particle detectors. GEANT4 is the ideal tool to study radiation transport and should be applied to space environments and the complex geometries of modern day spacecraft.

  3. Modelling PET radionuclide production in tissue and external targets using Geant4

    NASA Astrophysics Data System (ADS)

    Amin, T.; Infantino, A.; Lindsay, C.; Barlow, R.; Hoehr, C.

    2017-07-01

    The Proton Therapy Facility in TRIUMF provides 74 MeV protons extracted from a 500 MeV H- cyclotron for ocular melanoma treatments. During treatment, positron emitting radionuclides such as 1C, 15O and 13N are produced in patient tissue. Using PET scanners, the isotopic activity distribution can be measured for in-vivo range verification. A second cyclotron, the TR13, provides 13 MeV protons onto liquid targets for the production of PET radionuclides such as 18F, 13N or 68Ga, for medical applications. The aim of this work was to validate Geant4 against FLUKA and experimental measurements for production of the above-mentioned isotopes using the two cyclotrons. The results show variable degrees of agreement. For proton therapy, the proton-range agreement was within 2 mm for 11C activity, whereas 13N disagreed. For liquid targets at the TR13 the average absolute deviation ratio between FLUKA and experiment was 1.9±2.7, whereas the average absolute deviation ratio between Geant4 and experiment was 0. 6±0.4. This is due to the uncertainties present in experimentally determined reaction cross sections.

  4. A Virtual Geant4 Environment

    NASA Astrophysics Data System (ADS)

    Iwai, Go

    2015-12-01

    We describe the development of an environment for Geant4 consisting of an application and data that provide users with a more efficient way to access Geant4 applications without having to download and build the software locally. The environment is platform neutral and offers the users near-real time performance. In addition, the environment consists of data and Geant4 libraries built using low-level virtual machine (LLVM) tools which can produce bitcode that can be embedded in HTML and accessed via a browser. The bitcode is downloaded to the local machine via the browser and can then be configured by the user. This approach provides a way of minimising the risk of leaking potentially sensitive data used to construct the Geant4 model and application in the medical domain for treatment planning. We describe several applications that have used this approach and compare their performance with that of native applications. We also describe potential user communities that could benefit from this approach.

  5. Nuclear spectroscopy with Geant4. The superheavy challenge

    NASA Astrophysics Data System (ADS)

    Sarmiento, Luis G.

    2016-12-01

    The simulation toolkit Geant4 was originally developed at CERN for high-energy physics. Over the years it has been established as a swiss army knife not only in particle physics but it has seen an accelerated expansion towards nuclear physics and more recently to medical imaging and γ- and ion- therapy to mention but a handful of new applications. The validity of Geant4 is vast and large across many particles, ions, materials, and physical processes with typically various different models to choose from. Unfortunately, atomic nuclei with atomic number Z > 100 are not properly supported. This is likely due to the rather novelty of the field, its comparably small user base, and scarce evaluated experimental data. To circumvent this situation different workarounds have been used over the years. In this work the simulation toolkit Geant4 will be introduced with its different components and the effort to bring the software to the heavy and superheavy region will be described.

  6. Validation of nuclear models in Geant4 using the dose distribution of a 177 MeV proton pencil beam.

    PubMed

    Hall, David C; Makarova, Anastasia; Paganetti, Harald; Gottschalk, Bernard

    2016-01-07

    A proton pencil beam is associated with a surrounding low-dose envelope, originating from nuclear interactions. It is important for treatment planning systems to accurately model this envelope when performing dose calculations for pencil beam scanning treatments, and Monte Carlo (MC) codes are commonly used for this purpose. This work aims to validate the nuclear models employed by the Geant4 MC code, by comparing the simulated absolute dose distribution to a recent experiment of a 177 MeV proton pencil beam stopping in water. Striking agreement is observed over five orders of magnitude, with both the shape and normalisation well modelled. The normalisations of two depth dose curves are lower than experiment, though this could be explained by an experimental positioning error. The Geant4 neutron production model is also verified in the distal region. The entrance dose is poorly modelled, suggesting an unaccounted upstream source of low-energy protons. Recommendations are given for a follow-up experiment which could resolve these issues.

  7. Recent improvements on the description of hadronic interactions in Geant4

    NASA Astrophysics Data System (ADS)

    Dotti, A.; Apostolakis, J.; Folger, G.; Grichine, V.; Ivanchenko, V.; Kosov, M.; Ribon, A.; Uzhinsky, V.; Wright, D. H.

    2011-04-01

    We present an overview of recent improvements of hadronic models in Geant4 for the physics configurations (Physics Lists) relevant to applications in high energy experiments. During last year the improvements have concentrated on the study of unphysical discontinuities in calorimeter observables in the transition regions between the models used in Physics Lists. The microscopic origin of these have been investigated, and possible improvements of Geant4 code are currently under validation. In this paper we discuss the status of the latest version of Geant4 with emphasis on the most promising new developments, namely the Fritiof based and CHIPS Physics Lists.

  8. Assessment and improvements of Geant4 hadronic models in the context of prompt-gamma hadrontherapy monitoring.

    PubMed

    Dedes, G; Pinto, M; Dauvergne, D; Freud, N; Krimmer, J; Létang, J M; Ray, C; Testa, E

    2014-04-07

    Monte Carlo simulations are nowadays essential tools for a wide range of research topics in the field of radiotherapy. They also play an important role in the effort to develop a real-time monitoring system for quality assurance in proton and carbon ion therapy, by means of prompt-gamma detection. The internal theoretical nuclear models of Monte Carlo simulation toolkits are of decisive importance for the accurate description of neutral or charged particle emission, produced by nuclear interactions between beam particles and target nuclei. We assess the performance of Geant4 nuclear models in the context of prompt-gamma emission, comparing them with experimental data from proton and carbon ion beams. As has been shown in the past and further indicated in our study, the prompt-gamma yields are consistently overestimated by Geant4 by a factor of about 100% to 200% over an energy range from 80 to 310 MeV/u for the case of (12)C, and to a lesser extent for 160 MeV protons. Furthermore, we focus on the quantum molecular dynamics (QMD) modeling of ion-ion collisions, in order to optimize its description of light nuclei, which are abundant in the human body and mainly anticipated in hadrontherapy applications. The optimization has been performed by benchmarking QMD free parameters with well established nuclear properties. In addition, we study the effect of this optimization on charged particle emission. With the usage of the proposed parameter values, discrepancies reduce to less than 70%, with the highest values being attributed to the nucleon-ion induced prompt-gammas. This conclusion, also confirmed by the disagreement we observe in the case of proton beams, indicates the need for further investigation on nuclear models which describe proton and neutron induced nuclear reactions.

  9. Assessment and improvements of Geant4 hadronic models in the context of prompt-gamma hadrontherapy monitoring

    NASA Astrophysics Data System (ADS)

    Dedes, G.; Pinto, M.; Dauvergne, D.; Freud, N.; Krimmer, J.; Létang, J. M.; Ray, C.; Testa, E.

    2014-04-01

    Monte Carlo simulations are nowadays essential tools for a wide range of research topics in the field of radiotherapy. They also play an important role in the effort to develop a real-time monitoring system for quality assurance in proton and carbon ion therapy, by means of prompt-gamma detection. The internal theoretical nuclear models of Monte Carlo simulation toolkits are of decisive importance for the accurate description of neutral or charged particle emission, produced by nuclear interactions between beam particles and target nuclei. We assess the performance of Geant4 nuclear models in the context of prompt-gamma emission, comparing them with experimental data from proton and carbon ion beams. As has been shown in the past and further indicated in our study, the prompt-gamma yields are consistently overestimated by Geant4 by a factor of about 100% to 200% over an energy range from 80 to 310 MeV/u for the case of 12C, and to a lesser extent for 160 MeV protons. Furthermore, we focus on the quantum molecular dynamics (QMD) modeling of ion-ion collisions, in order to optimize its description of light nuclei, which are abundant in the human body and mainly anticipated in hadrontherapy applications. The optimization has been performed by benchmarking QMD free parameters with well established nuclear properties. In addition, we study the effect of this optimization on charged particle emission. With the usage of the proposed parameter values, discrepancies reduce to less than 70%, with the highest values being attributed to the nucleon-ion induced prompt-gammas. This conclusion, also confirmed by the disagreement we observe in the case of proton beams, indicates the need for further investigation on nuclear models which describe proton and neutron induced nuclear reactions.

  10. Interfacing the JQMD and JAM Nuclear Reaction Codes to Geant4

    SciTech Connect

    Koi, Tatsumi

    2003-06-17

    Geant4 is a toolkit for the simulation of the passage of particles through matter. It provides a comprehensive set of tools for geometry, tracking, detector response, run, event and track management, visualization and user interfaces. Geant4 also has an abundant set of physics models that handle the diverse interactions of particles with matter across a wide energy range. However, there are also many well-established reaction codes currently used in the same fields where Geant4 is applied. In order to take advantage of these codes, we began to investigate their use from within the framework of Geant4. The first codes chosen for this investigation were the Jaeri Quantum Molecular Dynamics (JQMD) and Jet AA Microscopic Transportation Model (JAM) codes. JQMD is a QMD model code which is widely used to analyze various aspects of heavy ion reactions. JAM is a hadronic cascade model code which explicitly treats all established hadronic states, including resonances with explicit spin and isospin, as well as their anti-particles. We successfully developed interfaces between these codes and Geant4. These allow a user to construct a detector using the powerful material and geometrical capabilities of Geant4, while at the same time implementing nuclear reactions handled by the JQMD and JAM models and the Hadronic framework of Geant4 proved its flexibility and expandability.

  11. Geant4 validation of neutron production on thick targets bombarded with 120 GeV protons

    NASA Astrophysics Data System (ADS)

    Sabra, Mohammad S.

    2015-09-01

    Neutron energy spectra and angular distributions are calculated for 120 GeV protons on thick graphite, aluminum, copper, and tungsten targets using relevant physics models within the Monte-Carlo simulation package Geant4. The calculations are compared to data from recent experiment. Discrepancies are observed between experimental data and Geant4 models, and suggest that improvements of the intra-(INC) and inter-nuclear cascade processes employed by the models are required.

  12. Galactic Cosmic Rays and Lunar Secondary Particles from Solar Minimum to Maximum: CRaTER Observations and Geant4 Modeling

    NASA Astrophysics Data System (ADS)

    Looper, M. D.; Mazur, J. E.; Blake, J. B.; Spence, H. E.; Schwadron, N.; Golightly, M. J.; Case, A. W.; Kasper, J. C.; Townsend, L. W.; Wilson, J. K.

    2014-12-01

    The Lunar Reconnaissance Orbiter mission was launched in 2009 during the recent deep and extended solar minimum, with the highest galactic cosmic ray (GCR) fluxes observed since the beginning of the space era. Its Cosmic Ray Telescope for the Effects of Radiation (CRaTER) instrument was designed to measure the spectra of energy deposits in silicon detectors shielded behind pieces of tissue equivalent plastic, simulating the self-shielding provided by an astronaut's body around radiation-sensitive organs. The CRaTER data set now covers the evolution of the GCR environment near the moon during the first five years of development of the present solar cycle. We will present these observations, along with Geant4 modeling to illustrate the varying particle contributions to the energy-deposit spectra. CRaTER has also measured protons traveling up from the lunar surface after their creation during GCR interactions with surface material, and we will report observations and modeling of the energy and angular distributions of these "albedo" protons.

  13. Allowing for crystalline structure effects in Geant4

    NASA Astrophysics Data System (ADS)

    Bagli, Enrico; Asai, Makoto; Dotti, Andrea; Pandola, Luciano; Verderi, Marc

    2017-07-01

    In recent years, the Geant4 toolkit for the Monte Carlo simulation of radiation with matter has seen large growth in its divers user community. A fundamental aspect of a successful physics experiment is the availability of a reliable and precise simulation code. Geant4 currently does not allow for the simulation of particle interactions with anything other than amorphous matter. To overcome this limitation, the GECO (GEant4 Crystal Objects) project developed a general framework for managing solid-state structures in the Geant4 kernel and validate it against experimental data. Accounting for detailed geometrical structures allows, for example, simulation of diffraction from crystal planes or the channeling of charged particle.

  14. The Lunar Radiation Environment: LRO/CRaTER Observations and Geant4 Modeling

    NASA Astrophysics Data System (ADS)

    Looper, M. D.; Mazur, J.; Blake, J. B.; Spence, H. E.; Golightly, M.; Case, A. W.

    2010-12-01

    The Cosmic Ray Telescope for the Effects of Radiation (CRaTER) has been in orbit around the moon aboard the Lunar Reconnaissance Orbiter (LRO) for over a year. The purpose of CRaTER is to measure the radiation environment that will be experienced, in particular, by astronauts on and near the lunar surface; to that end, CRaTER consists of a "telescope" of six silicon solid state detectors arranged in three pairs, with two large blocks of Tissue-Equivalent Plastic between pairs to represent the shielding provided by the human body. The data we have collected to date are complex, and to understand our observations we have performed extensive modeling of the "albedo" particles produced by interactions of primary cosmic rays with the lunar surface and with the spacecraft itself, and of the response of the sensor to both primary and albedo particles. We will present measurements of the Linear Energy Transfer (LET) and dose from CRaTER, and will show more generic LET and dose spectra, using our models to remove the effects specific to the CRaTER sensor geometry and spacecraft environment (shielding, locally-produced albedo), for lunar orbit and at the lunar surface.

  15. Geant4 Applications in Space

    SciTech Connect

    Asai, M.; /SLAC

    2007-11-07

    Use of Geant4 is rapidly expanding in space application domain. I try to overview three major application areas of Geant4 in space, which are apparatus simulation for pre-launch design and post-launch analysis, planetary scale simulation for radiation spectra and surface and sub-surface explorations, and micro-dosimetry simulation for single event study and radiation-hardening of semiconductor devices. Recently, not only the mission dependent applications but also various multi-purpose or common tools built on top of Geant4 are also widely available. I overview some of such tools as well. The Geant4 Collaboration identifies that the space applications are now one of the major driving forces of the further developments and refinements of Geant4 toolkit. Highlights of such developments are introduced.

  16. Calculation of lineal energies for water and DNA bases using the Rudd model cross sections integrated within the Geant4-DNA processes

    NASA Astrophysics Data System (ADS)

    Francis, Z.; El Bitar, Z.; Incerti, S.; Bernal, M. A.; Karamitros, M.; Tran, H. N.

    2017-07-01

    This study presents new parameters for proton ionisation cross sections in guanine, adenine, thymine, and cytosine based upon the semi-empirical Rudd model. The same model was used to find differential electron cross sections considering a speed scaling procedure. To accelerate computation, the total electron cross sections were obtained using the binary-encounter-Bethe approximation instead of the integrated Rudd formula. The cross sections were implemented in the Geant4 simulation toolkit as Geant4-DNA processes, and simulations were carried out measuring protons lineal energies in spherical micrometric volumes filled with water, adenine, thymine, guanine, and cytosine. Large differences were seen in the lineal energies evaluated for the different materials, with the lineal energy measured in guanine being sometimes twice that of water. This suggests that the cross sections developed here should be considered in biological simulations where cellular substructures are modelled, in contrast to the current approach which approximates these volumes as consisting of liquid water.

  17. Space and Medical Applications of the Geant4 Simulation Toolkit

    NASA Astrophysics Data System (ADS)

    Perl, Joseph

    2008-10-01

    Geant4 is a toolkit to simulate the passage of particles through matter. While Geant4 was developed for High Energy Physics (HEP), applications now include Nuclear, Medical and Space Physics. Medical applications have been increasing rapidly due to the overall growth of Monte Carlo in Medical Physics and the unique qualities of Geant4 as an all-particle code able to handle complex geometry, motion and fields with the flexibility of modern programming and an open free source code. Work has included characterizing beams and sources, treatment planning and imaging. The all-particle nature of Geant4 has made it popular for the newest modes of radiation treatment: Proton and Particle therapy. Geant4 has been used by ESA, NASA and JAXA to study radiation effects to spacecraft and personnel. The flexibility of Geant4 has enabled teams to incorporate it into their own applications (SPENVIS MULASSIS space environment from QinetiQ and ESA, RADSAFE simulation from Vanderbilt University and NASA). We provide an overview of applications and discuss how Geant4 has responded to specific challenges of moving from HEP to Medical and Space Physics, including recent work to extend Geant4's energy range to low dose radiobiology.

  18. First statistical analysis of Geant4 quality software metrics

    NASA Astrophysics Data System (ADS)

    Ronchieri, Elisabetta; Grazia Pia, Maria; Giacomini, Francesco

    2015-12-01

    Geant4 is a simulation system of particle transport through matter, widely used in several experimental areas from high energy physics and nuclear experiments to medical studies. Some of its applications may involve critical use cases; therefore they would benefit from an objective assessment of the software quality of Geant4. In this paper, we provide a first statistical evaluation of software metrics data related to a set of Geant4 physics packages. The analysis aims at identifying risks for Geant4 maintainability, which would benefit from being addressed at an early stage. The findings of this pilot study set the grounds for further extensions of the analysis to the whole of Geant4 and to other high energy physics software systems.

  19. Geant4 Computing Performance Benchmarking and Monitoring

    DOE PAGES

    Dotti, Andrea; Elvira, V. Daniel; Folger, Gunter; ...

    2015-12-23

    Performance evaluation and analysis of large scale computing applications is essential for optimal use of resources. As detector simulation is one of the most compute intensive tasks and Geant4 is the simulation toolkit most widely used in contemporary high energy physics (HEP) experiments, it is important to monitor Geant4 through its development cycle for changes in computing performance and to identify problems and opportunities for code improvements. All Geant4 development and public releases are being profiled with a set of applications that utilize different input event samples, physics parameters, and detector configurations. Results from multiple benchmarking runs are compared tomore » previous public and development reference releases to monitor CPU and memory usage. Observed changes are evaluated and correlated with code modifications. Besides the full summary of call stack and memory footprint, a detailed call graph analysis is available to Geant4 developers for further analysis. The set of software tools used in the performance evaluation procedure, both in sequential and multi-threaded modes, include FAST, IgProf and Open|Speedshop. In conclusion, the scalability of the CPU time and memory performance in multi-threaded application is evaluated by measuring event throughput and memory gain as a function of the number of threads for selected event samples.« less

  20. Geant4 Computing Performance Benchmarking and Monitoring

    SciTech Connect

    Dotti, Andrea; Elvira, V. Daniel; Folger, Gunter; Genser, Krzysztof; Jun, Soon Yung; Kowalkowski, James B.; Paterno, Marc

    2015-12-23

    Performance evaluation and analysis of large scale computing applications is essential for optimal use of resources. As detector simulation is one of the most compute intensive tasks and Geant4 is the simulation toolkit most widely used in contemporary high energy physics (HEP) experiments, it is important to monitor Geant4 through its development cycle for changes in computing performance and to identify problems and opportunities for code improvements. All Geant4 development and public releases are being profiled with a set of applications that utilize different input event samples, physics parameters, and detector configurations. Results from multiple benchmarking runs are compared to previous public and development reference releases to monitor CPU and memory usage. Observed changes are evaluated and correlated with code modifications. Besides the full summary of call stack and memory footprint, a detailed call graph analysis is available to Geant4 developers for further analysis. The set of software tools used in the performance evaluation procedure, both in sequential and multi-threaded modes, include FAST, IgProf and Open|Speedshop. In conclusion, the scalability of the CPU time and memory performance in multi-threaded application is evaluated by measuring event throughput and memory gain as a function of the number of threads for selected event samples.

  1. GEANT4 distributed computing for compact clusters

    NASA Astrophysics Data System (ADS)

    Harrawood, Brian P.; Agasthya, Greeshma A.; Lakshmanan, Manu N.; Raterman, Gretchen; Kapadia, Anuj J.

    2014-11-01

    A new technique for distribution of GEANT4 processes is introduced to simplify running a simulation in a parallel environment such as a tightly coupled computer cluster. Using a new C++ class derived from the GEANT4 toolkit, multiple runs forming a single simulation are managed across a local network of computers with a simple inter-node communication protocol. The class is integrated with the GEANT4 toolkit and is designed to scale from a single symmetric multiprocessing (SMP) machine to compact clusters ranging in size from tens to thousands of nodes. User designed 'work tickets' are distributed to clients using a client-server work flow model to specify the parameters for each individual run of the simulation. The new g4DistributedRunManager class was developed and well tested in the course of our Neutron Stimulated Emission Computed Tomography (NSECT) experiments. It will be useful for anyone running GEANT4 for large discrete data sets such as covering a range of angles in computed tomography, calculating dose delivery with multiple fractions or simply speeding the through-put of a single model.

  2. Calculation of electron Dose Point Kernel in water with GEANT4 for medical application

    SciTech Connect

    Guimaraes, C. C.; Sene, F. F.; Martinelli, J. R.

    2009-06-03

    The rapid insertion of new technologies in medical physics in the last years, especially in nuclear medicine, has been followed by a great development of faster Monte Carlo algorithms. GEANT4 is a Monte Carlo toolkit that contains the tools to simulate the problems of particle transport through matter. In this work, GEANT4 was used to calculate the dose-point-kernel (DPK) for monoenergetic electrons in water, which is an important reference medium for nuclear medicine. The three different physical models of electromagnetic interactions provided by GEANT4 - Low Energy, Penelope and Standard - were employed. To verify the adequacy of these models, the results were compared with references from the literature. For all energies and physical models, the agreement between calculated DPKs and reported values is satisfactory.

  3. Review of Geant4-DNA applications for micro and nanoscale simulations.

    PubMed

    Incerti, S; Douglass, M; Penfold, S; Guatelli, S; Bezak, E

    2016-10-01

    Emerging radiotherapy treatments including targeted particle therapy, hadron therapy or radiosensitisation of cells by high-Z nanoparticles demand the theoretical determination of radiation track structure at the nanoscale. This is essential in order to evaluate radiation damage at the cellular and DNA level. Since 2007, Geant4 offers physics models to describe particle interactions in liquid water at the nanometre level through the Geant4-DNA Package. This package currently provides a complete set of models describing the event-by-event electromagnetic interactions of particles with liquid water, as well as developments for the modelling of water radiolysis. Since its release, Geant4-DNA has been adopted as an investigational tool in kV and MV external beam radiotherapy, hadron therapies using protons and heavy ions, targeted therapies and radiobiology studies. It has been benchmarked with respect to other track structure Monte Carlo codes and, where available, against reference experimental measurements. While Geant4-DNA physics models and radiolysis modelling functionalities have already been described in detail in the literature, this review paper summarises and discusses a selection of representative papers with the aim of providing an overview of a) geometrical descriptions of biological targets down to the DNA size, and b) the full spectrum of current micro- and nano-scale applications of Geant4-DNA.

  4. GEANT4 Tuning For pCT Development

    NASA Astrophysics Data System (ADS)

    Yevseyeva, Olga; de Assis, Joaquim T.; Evseev, Ivan; Schelin, Hugo R.; Paschuk, Sergei A.; Milhoretto, Edney; Setti, João A. P.; Díaz, Katherin S.; Hormaza, Joel M.; Lopes, Ricardo T.

    2011-08-01

    Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Thus, the fidelity of proton computed tomography (pCT) simulations as a tool for proton therapy planning depends in the general case on the accuracy of results obtained for the proton interaction with thick absorbers. GEANT4 simulations of proton energy spectra after passing thick absorbers do not agree well with existing experimental data, as showed previously. Moreover, the spectra simulated for the Bethe-Bloch domain showed an unexpected sensitivity to the choice of low-energy electromagnetic models during the code execution. These observations were done with the GEANT4 version 8.2 during our simulations for pCT. This work describes in more details the simulations of the proton passage through aluminum absorbers with varied thickness. The simulations were done by modifying only the geometry in the Hadrontherapy Example, and for all available choices of the Electromagnetic Physics Models. As the most probable reasons for these effects is some specific feature in the code, or some specific implicit parameters in the GEANT4 manual, we continued our study with version 9.2 of the code. Some improvements in comparison with our previous results were obtained. The simulations were performed considering further applications for pCT development.

  5. Dose calculations at high altitudes and in deep space with GEANT4 using BIC and JQMD models for nucleus nucleus reactions

    NASA Astrophysics Data System (ADS)

    Sihver, L.; Matthiä, D.; Koi, T.; Mancusi, D.

    2008-10-01

    Radiation exposure of aircrew is more and more recognized as an occupational hazard. The ionizing environment at standard commercial aircraft flight altitudes consists mainly of secondary particles, of which the neutrons give a major contribution to the dose equivalent. Accurate estimations of neutron spectra in the atmosphere are therefore essential for correct calculations of aircrew doses. Energetic solar particle events (SPE) could also lead to significantly increased dose rates, especially at routes close to the North Pole, e.g. for flights between Europe and USA. It is also well known that the radiation environment encountered by personnel aboard low Earth orbit (LEO) spacecraft or aboard a spacecraft traveling outside the Earth's protective magnetosphere is much harsher compared with that within the atmosphere since the personnel are exposed to radiation from both galactic cosmic rays (GCR) and SPE. The relative contribution to the dose from GCR when traveling outside the Earth's magnetosphere, e.g. to the Moon or Mars, is even greater, and reliable and accurate particle and heavy ion transport codes are essential to calculate the radiation risks for both aircrew and personnel on spacecraft. We have therefore performed calculations of neutron distributions in the atmosphere, total dose equivalents, and quality factors at different depths in a water sphere in an imaginary spacecraft during solar minimum in a geosynchronous orbit. The calculations were performed with the GEANT4 Monte Carlo (MC) code using both the binary cascade (BIC) model, which is part of the standard GEANT4 package, and the JQMD model, which is used in the particle and heavy ion transport code PHITS GEANT4.

  6. Microdosimetry calculations for monoenergetic electrons using Geant4-DNA combined with a weighted track sampling algorithm

    NASA Astrophysics Data System (ADS)

    Famulari, Gabriel; Pater, Piotr; Enger, Shirin A.

    2017-07-01

    The aim of this study was to calculate microdosimetric distributions for low energy electrons simulated using the Monte Carlo track structure code Geant4-DNA. Tracks for monoenergetic electrons with kinetic energies ranging from 100 eV to 1 MeV were simulated in an infinite spherical water phantom using the Geant4-DNA extension included in Geant4 toolkit version 10.2 (patch 02). The microdosimetric distributions were obtained through random sampling of transfer points and overlaying scoring volumes within the associated volume of the tracks. Relative frequency distributions of energy deposition f(>E)/f(>0) and dose mean lineal energy (\\bar{y}D ) values were calculated in nanometer-sized spherical and cylindrical targets. The effects of scoring volume and scoring techniques were examined. The results were compared with published data generated using MOCA8B and KURBUC. Geant4-DNA produces a lower frequency of higher energy deposits than MOCA8B. The \\bar{y}D values calculated with Geant4-DNA are smaller than those calculated using MOCA8B and KURBUC. The differences are mainly due to the lower ionization and excitation cross sections of Geant4-DNA for low energy electrons. To a lesser extent, discrepancies can also be attributed to the implementation in this study of a new and fast scoring technique that differs from that used in previous studies. For the same mean chord length (\\bar{l} ), the \\bar{y}D calculated in cylindrical volumes are larger than those calculated in spherical volumes. The discrepancies due to cross sections and scoring geometries increase with decreasing scoring site dimensions. A new set of \\bar{y}D values has been presented for monoenergetic electrons using a fast track sampling algorithm and the most recent physics models implemented in Geant4-DNA. This dataset can be combined with primary electron spectra to predict the radiation quality of photon and electron beams.

  7. Allowing for crystalline structure effects in Geant4

    DOE PAGES

    Bagli, Enrico; Asai, Makoto; Dotti, Andrea; ...

    2017-03-24

    In recent years, the Geant4 toolkit for the Monte Carlo simulation of radiation with matter has seen large growth in its divers user community. A fundamental aspect of a successful physics experiment is the availability of a reliable and precise simulation code. Geant4 currently does not allow for the simulation of particle interactions with anything other than amorphous matter. To overcome this limitation, the GECO (GEant4 Crystal Objects) project developed a general framework for managing solid-state structures in the Geant4 kernel and validate it against experimental data. As a result, accounting for detailed geometrical structures allows, for example, simulation ofmore » diffraction from crystal planes or the channeling of charged particle.« less

  8. Radiation Effects Investigations Based on Atmospheric Radiation Model (ATMORAD) Considering GEANT4 Simulations of Extensive Air Showers and Solar Modulation Potential.

    PubMed

    Hubert, Guillaume; Cheminet, Adrien

    2015-07-01

    The natural radiative atmospheric environment is composed of secondary cosmic rays produced when primary cosmic rays hit the atmosphere. Understanding atmospheric radiations and their dynamics is essential for evaluating single event effects, so that radiation risks in aviation and the space environment (space weather) can be assessed. In this article, we present an atmospheric radiation model, named ATMORAD (Atmospheric Radiation), which is based on GEANT4 simulations of extensive air showers according to primary spectra that depend only on the solar modulation potential (force-field approximation). Based on neutron spectrometry, solar modulation potential can be deduced using neutron spectrometer measurements and ATMORAD. Some comparisons between our methodology and standard approaches or measurements are also discussed. This work demonstrates the potential for using simulations of extensive air showers and neutron spectroscopy to monitor solar activity.

  9. Benchmarking Geant4 for spallation neutron source calculations

    NASA Astrophysics Data System (ADS)

    DiJulio, Douglas D.; Batkov, Konstantin; Stenander, John; Cherkashyna, Nataliia; Bentley, Phillip M.

    2016-09-01

    Geant4 is becoming increasingly used for radiation transport simulations of spallation neutron sources and related components. Historically, the code has seen little usage in this field and it is of general interest to investigate the suitability of Geant4 for such applications. For this purpose, we carried out Geant4 calculations based on simple spallation source geometries and also with the the European Spallation Source Technical Design Report target and moderator configuration. The results are compared to calculations performed with the Monte Carlo N- Particle extended code. The comparisons are carried out over the full spallation neutron source energy spectrum, from sub-eV energies up to thousands of MeV. Our preliminary results reveal that there is generally good agreement between the simulations using both codes. Additionally, we have also implemented a general weight-window generator for Geant4 based applications and present some results of the method applied to the ESS target model.

  10. SU-E-T-565: RAdiation Resistance of Cancer CElls Using GEANT4 DNA: RACE

    SciTech Connect

    Perrot, Y; Payno, H; Delage, E; Maigne, L

    2014-06-01

    Purpose: The objective of the RACE project is to develop a comparison between Monte Carlo simulation using the Geant4-DNA toolkit and measurements of radiation damage on 3D melanoma and chondrosarcoma culture cells coupled with gadolinium nanoparticles. We currently expose the status of the developments regarding simulations. Methods: Monte Carlo studies are driven using the Geant4 toolkit and the Geant4-DNA extension. In order to model the geometry of a cell population, the opensource CPOP++ program is being developed for the geometrical representation of 3D cell populations including a specific cell mesh coupled with a multi-agent system. Each cell includes cytoplasm and nucleus. The correct modeling of the cell population has been validated with confocal microscopy images of spheroids. The Geant4 Livermore physics models are used to simulate the interactions of a 250 keV X-ray beam and the production of secondaries from gadolinium nanoparticles supposed to be fixed on the cell membranes. Geant4-DNA processes are used to simulate the interactions of charged particles with the cells. An atomistic description of the DNA molecule, from PDB (Protein Data Bank) files, is provided by the so-called PDB4DNA Geant4 user application we developed to score energy depositions in DNA base pairs and sugar-phosphate groups. Results: At the microscopic level, our simulations enable assessing microscopic energy distribution in each cell compartment of a realistic 3D cell population. Dose enhancement factors due to the presence of gadolinium nanoparticles can be estimated. At the nanometer scale, direct damages on nuclear DNA are also estimated. Conclusion: We successfully simulated the impact of direct radiations on a realistic 3D cell population model compatible with microdosimetry calculations using the Geant4-DNA toolkit. Upcoming validation and the future integration of the radiochemistry module of Geant4-DNA will propose to correlate clusters of ionizations with in vitro

  11. Geant4 Monte Carlo simulation of energy loss and transmission and ranges for electrons, protons and ions

    NASA Astrophysics Data System (ADS)

    Ivantchenko, Vladimir

    Geant4 is a toolkit for Monte Carlo simulation of particle transport originally developed for applications in high-energy physics with the focus on experiments at the Large Hadron Collider (CERN, Geneva). The transparency and flexibility of the code has spread its use to other fields of research, e.g. radiotherapy and space science. The tool provides possibility to simulate complex geometry, transportation in electric and magnetic fields and variety of physics models of interaction of particles with media. Geant4 has been used for simulation of radiation effects for number of space missions. Recent upgrades of the toolkit released in December 2009 include new model for ion electronic stopping power based on the revised version of ICRU'73 Report increasing accuracy of simulation of ion transport. In the current work we present the status of Geant4 electromagnetic package for simulation of particle energy loss, ranges and transmission. This has a direct implication for simulation of ground testing setups at existing European facilities and for simulation of radiation effects in space. A number of improvements were introduced for electron and proton transport, followed by a thorough validation. It was the aim of the present study to validate the range against reference data from the United States National Institute of Standards and Technologies (NIST) ESTAR, PSTAR and ASTAR databases. We compared Geant4 and NIST ranges of electrons using different Geant4 models. The best agreement was found for Penelope, except at very low energies in heavy materials, where the Standard package gave better results. Geant4 proton ranges in water agreed with NIST within 1 The validation of the new ion model is performed against recent data on Bragg peak position in water. The data from transmission of carbon ions via various absorbers following Bragg peak in water demonstrate that the new Geant4 model significantly improves precision of ion range. The absolute accuracy of ion range

  12. Geant4 simulations of a wide-angle x-ray focusing telescope

    NASA Astrophysics Data System (ADS)

    Zhao, Donghua; Zhang, Chen; Yuan, Weimin; Zhang, Shuangnan; Willingale, Richard; Ling, Zhixing

    2017-06-01

    The rapid development of X-ray astronomy has been made possible by widely deploying X-ray focusing telescopes on board many X-ray satellites. Geant4 is a very powerful toolkit for Monte Carlo simulations and has remarkable abilities to model complex geometrical configurations. However, the library of physical processes available in Geant4 lacks a description of the reflection of X-ray photons at a grazing incident angle which is the core physical process in the simulation of X-ray focusing telescopes. The scattering of low-energy charged particles from the mirror surfaces is another noteworthy process which is not yet incorporated into Geant4. Here we describe a Monte Carlo model of a simplified wide-angle X-ray focusing telescope adopting lobster-eye optics and a silicon detector using the Geant4 toolkit. With this model, we simulate the X-ray tracing, proton scattering and background detection. We find that: (1) the effective area obtained using Geant4 is in agreement with that obtained using Q software with an average difference of less than 3%; (2) X-rays are the dominant background source below 10 keV; (3) the sensitivity of the telescope is better by at least one order of magnitude than that of a coded mask telescope with the same physical dimensions; (4) the number of protons passing through the optics and reaching the detector by Firsov scattering is about 2.5 times that of multiple scattering for the lobster-eye telescope.

  13. Geant4 simulations of a wide-angle x-ray focusing telescope

    NASA Astrophysics Data System (ADS)

    Zhao, Donghua; Zhang, Chen; Yuan, Weimin; Zhang, Shuangnan; Willingale, Richard; Ling, Zhixing

    2017-03-01

    The rapid development of X-ray astronomy has been made possible by widely deploying X-ray focusing telescopes on board many X-ray satellites. Geant4 is a very powerful toolkit for Monte Carlo simulations and has remarkable abilities to model complex geometrical configurations. However, the library of physical processes available in Geant4 lacks a description of the reflection of X-ray photons at a grazing incident angle which is the core physical process in the simulation of X-ray focusing telescopes. The scattering of low-energy charged particles from the mirror surfaces is another noteworthy process which is not yet incorporated into Geant4. Here we describe a Monte Carlo model of a simplified wide-angle X-ray focusing telescope adopting lobster-eye optics and a silicon detector using the Geant4 toolkit. With this model, we simulate the X-ray tracing, proton scattering and background detection. We find that: (1) the effective area obtained using Geant4 is in agreement with that obtained using Q software with an average difference of less than 3%; (2) X-rays are the dominant background source below 10 keV; (3) the sensitivity of the telescope is better by at least one order of magnitude than that of a coded mask telescope with the same physical dimensions; (4) the number of protons passing through the optics and reaching the detector by Firsov scattering is about 2.5 times that of multiple scattering for the lobster-eye telescope.

  14. Validation of Geant4 10.3 simulation of proton interaction for space radiation effects

    NASA Astrophysics Data System (ADS)

    Ivanchenko, Vladimir; Dondero, Paolo; Fioretti, Valentina; Ivantchenko, Anton; Lei, Fan; Lotti, Simone; Mantero, Alfonso; Mineo, Teresa

    2017-08-01

    Monte Carlo simulation of space radiation effects induced by protons is important for design of space missions. Geant4 is a well established toolkit for Monte Carlo simulation focused on high energy physics applications. In this work, a set of new validation results versus data for Geant4 electromagnetic and hadronic interaction of protons is presented and discussed. Optimal configuration of Geant4 physics for space applications is proposed.

  15. Identifying key surface parameters for optical photon transport in GEANT4/GATE simulations.

    PubMed

    Nilsson, Jenny; Cuplov, Vesna; Isaksson, Mats

    2015-09-01

    For a scintillator used for spectrometry, the generation, transport and detection of optical photons have a great impact on the energy spectrum resolution. A complete Monte Carlo model of a scintillator includes a coupled ionizing particle and optical photon transport, which can be simulated with the GEANT4 code. The GEANT4 surface parameters control the physics processes an optical photon undergoes when reaching the surface of a volume. In this work the impact of each surface parameter on the optical transport was studied by looking at the optical spectrum: the number of detected optical photons per ionizing source particle from a large plastic scintillator, i.e. the output signal. All simulations were performed using GATE v6.2 (GEANT4 Application for Tomographic Emission). The surface parameter finish (polished, ground, front-painted or back-painted) showed the greatest impact on the optical spectrum whereas the surface parameter σ(α), which controls the surface roughness, had a relatively small impact. It was also shown how the surface parameters reflectivity and reflectivity types (specular spike, specular lobe, Lambertian and backscatter) changed the optical spectrum depending on the probability for reflection and the combination of reflectivity types. A change in the optical spectrum will ultimately have an impact on a simulated energy spectrum. By studying the optical spectra presented in this work, a GEANT4 user can predict the shift in an optical spectrum caused be the alteration of a specific surface parameter.

  16. Visualization drivers for Geant4

    SciTech Connect

    Beretvas, Andy; /Fermilab

    2005-10-01

    This document is on Geant4 visualization tools (drivers), evaluating pros and cons of each option, including recommendations on which tools to support at Fermilab for different applications. Four visualization drivers are evaluated. They are OpenGL, HepRep, DAWN and VRML. They all have good features, OpenGL provides graphic output without an intermediate file. HepRep provides menus to assist the user. DAWN provides high quality plots and even for large files produces output quickly. VRML uses the smallest disk space for intermediate files. Large experiments at Fermilab will want to write their own display. They should proceed to make this display graphics independent. Medium experiment will probably want to use HepRep because of it's menu support. Smaller scale experiments will want to use OpenGL in the spirit of having immediate response, good quality output and keeping things simple.

  17. Geant4-based radiation hazard assessment for human exploration missions

    NASA Astrophysics Data System (ADS)

    Bernabeu, J.; Casanova, I.

    Most of the radiation effects assessment methods on human crews are constrained to the Low Earth Orbit environment However the forthcoming Solar System exploration missions will encounter a totally different radiation environment as there is no shielding provided by the geomagnetic field In this work we present the first results on the simulation of geomagnetically unshielded Solar Energetic Particles SEP events and Galactic Cosmic Rays GCR impinging on a very simple spacecraft geometry We have used MULASSIS Multi-Layered Shielding Simulation Software a Monte Carlo code based on Geant4 developed for the European Space Agency Geant4 is a high energy physics toolkit originally developed at CERN to simulate particle interactions in high energy accelerators recently applied to space radiation protection studies Our setup consists of two semi-infinite parallel slabs the spacecraft shield and a 30 cm water phantom representing a human body Simulations have been carried out for different shielding materials and thicknesses assessing the dose and dose equivalent received by the phantom for different radiation sources SEP events have been simulated using an evolution of the JPL-91 model for worst-case conditions in solar maximum and some selected extreme events Our results show that a 20 g cm -2 shield of polyethylene is enough for having a dose below 10 mSv though the risk of exposure depends on the number of extreme events taking place throughout the duration of the mission GCR simulations are based on CREME96 fluences for

  18. Geant4 - Towards major release 10

    NASA Astrophysics Data System (ADS)

    Cosmo, G.; Geant4 Collaboration

    2014-06-01

    The Geant4 simulation toolkit has reached maturity in the middle of the previous decade, providing a wide variety of established features coherently aggregated in a software product, which has become the standard for detector simulation in HEP and is used in a variety of other application domains. We review the most recent capabilities introduced in the kernel, highlighting those, which are being prepared for the next major release (version 10.0) that is scheduled for the end of 2013. A significant new feature contained in this release will be the integration of multi-threading processing, aiming at targeting efficient use of modern many-cores system architectures and minimization of the memory footprint for exploiting event-level parallelism. We discuss its design features and impact on the existing API and user-interface of Geant4. Revisions are made to balance the need for preserving backwards compatibility and to consolidate and improve the interfaces; taking into account requirements from the multithreaded extensions and from the evolution of the data processing models of the LHC experiments.

  19. Probing Planetary Bodies for Subsurface Volatiles: GEANT4 Models of Gamma Ray, Fast, Epithermal, and Thermal Neutron Response to Active Neutron Illumination

    NASA Astrophysics Data System (ADS)

    Chin, G.; Sagdeev, R.; Su, J. J.; Murray, J.

    2014-12-01

    Using an active source of neutrons as an in situ probe of a planetary body has proven to be a powerful tool to extract information about the presence, abundance, and location of subsurface volatiles without the need for drilling. The Dynamic Albedo of Neutrons (DAN) instrument on Curiosity is an example of such an instrument and is designed to detect the location and abundance of hydrogen within the top 50 cm of the Martian surface. DAN works by sending a pulse of neutrons towards the ground beneath the rover and detecting the reflected neutrons. The intensity and time of arrival of the reflection depends on the proportion of water, while the time the pulse takes to reach the detector is a function of the depth at which the water is located. Similar instruments can also be effective probes at the polar-regions of the Moon or on asteroids as a way of detecting sequestered volatiles. We present the results of GEANT4 particle simulation models of gamma ray, fast, epithermal, and thermal neutron responses to active neutron illumination. The results are parameterized by hydrogen abundance, stratification and depth of volatile layers, versus the distribution of neutron and gamma ray energy reflections. Models will be presented to approximate Martian, lunar, and asteroid environments and would be useful tools to assess utility for future NASA exploration missions to these types of planetary bodies.

  20. Geant4 simulations of the neutron production and transport in the n_TOF spallation target

    NASA Astrophysics Data System (ADS)

    Lerendegui-Marco, J.; Cortés-Giraldo, M. A.; Guerrero, C.; Quesada, J. M.

    2016-11-01

    The neutron production and transport in the spallation target of the n_TOF facility at CERN has been simulated with Geant4. The results obtained with the different hadronic Physics Lists provided by Geant4 have been compared with the experimental neutron flux in n_TOF-EAR1. The best overall agreement in both the absolute value and the energy dependence of the flux from thermal to 1GeV, is obtained with the INCL++ model coupled with the Fritiof Model(FTFP). This Physics List has been thus used to simulate and study the main features of the new n_TOF-EAR2 beam line, currently in its commissioning phase.

  1. Geant4 application in a Web browser

    NASA Astrophysics Data System (ADS)

    Garnier, Laurent; Geant4 Collaboration

    2014-06-01

    Geant4 is a toolkit for the simulation of the passage of particles through matter. The Geant4 visualization system supports many drivers including OpenGL[1], OpenInventor, HepRep[2], DAWN[3], VRML, RayTracer, gMocren[4] and ASCIITree, with diverse and complementary functionalities. Web applications have an increasing role in our work, and thanks to emerging frameworks such as Wt [5], building a web application on top of a C++ application without rewriting all the code can be done. Because the Geant4 toolkit's visualization and user interface modules are well decoupled from the rest of Geant4, it is straightforward to adapt these modules to render in a web application instead of a computer's native window manager. The API of the Wt framework closely matches that of Qt [6], our experience in building Qt driver will benefit for Wt driver. Porting a Geant4 application to a web application is easy, and with minimal effort, Geant4 users can replicate this process to share their own Geant4 applications in a web browser.

  2. Comparative study of dose distributions and cell survival fractions for 1H, 4He, 12C and 16O beams using Geant4 and Microdosimetric Kinetic model

    NASA Astrophysics Data System (ADS)

    Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2015-04-01

    Depth and radial dose profiles for therapeutic 1H, 4He, 12C and 16O beams are calculated using the Geant4-based Monte Carlo model for Heavy-Ion Therapy (MCHIT). 4He and 16O ions are presented as alternative options to 1H and 12C broadly used for ion-beam cancer therapy. Biological dose profiles and survival fractions of cells are estimated using the modified Microdosimetric Kinetic model. Depth distributions of cell survival of healthy tissues, assuming 10% and 50% survival of tumor cells, are calculated for 6 cm SOBPs at two tumor depths and for different tissues radiosensitivities. It is found that the optimal ion choice depends on (i) depth of the tumor, (ii) dose levels and (iii) the contrast of radiosensitivities of tumor and surrounding healthy tissues. Our results indicate that 12C and 16O ions are more appropriate to spare healthy tissues in the case of a more radioresistant tumor at moderate depths. On the other hand, a sensitive tumor surrounded by more resistant tissues can be better treated with 1H and 4He ions. In general, 4He beam is found to be a good candidate for therapy. It better spares healthy tissues in all considered cases compared to 1H. Besides, the dose conformation is improved for deep-seated tumors compared to 1H, and the damage to surrounding healthy tissues is reduced compared to heavier ions due to the lower impact of nuclear fragmentation. No definite advantages of 16O with respect to 12C ions are found in this study.

  3. Beam Simulation Tools for GEANT4 (BT-V1.0). User's Guide

    SciTech Connect

    Elvira, V. Daniel; Lebrum, P.; Spentzouris, P.

    2002-12-02

    Geant4 is a tool kit developed by a collaboration of physicists and computer professionals in the high energy physics field for simulation of the passage of particles through matter. The motivation for the development of the Beam Tools is to extend the Geant4 applications to accelerator physics. The Beam Tools are a set of C++ classes designed to facilitate the simulation of accelerator elements: r.f. cavities, magnets, absorbers, etc. These elements are constructed from Geant4 solid volumes like boxes, tubes, trapezoids, or spheers. There are many computer programs for beam physics simulations, but Geant4 is ideal to model a beam through a material or to integrate a beam line with a complex detector. There are many such examples in the current international High Energy Physics programs. For instance, an essential part of the R&D associated with the Neutrino Source/Muon Collider accelerator is the ionization cooling channel, which is a section of the system aimed to reduce the size of the muon beam in phase space. The ionization cooling technique uses a combination of linacs and light absorbers to reduce the transverse momentum and size of the beam, while keeping the longitudinal momentum constant. The MuCool/MICE (muon cooling) experiments need accurate simulations of the beam transport through the cooling channel in addition to a detailed simulation of the detectors designed to measure the size of the beam. The accuracy of the models for physics processes associated with muon ionization and multiple scattering is critical in this type of applications. Another example is the simulation of the interaction region in future accelerators. The high luminosity and background environments expected in the Next Linear Collider (NLC) and the Very Large Hadron Collider (VLHC) pose great demand on the detectors, which may be optimized by means of a simulation of the detector-accelerator interface.

  4. Lateral variations of radiobiological properties of therapeutic fields of (1)H, (4)He, (12)C and (16)O ions studied with Geant4 and microdosimetric kinetic model.

    PubMed

    Dewey, Sophie; Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2017-06-27

    As known, in cancer therapy with ion beams the relative biological effectiveness (RBE) of ions changes in the course of their propagation in tissues. Such changes are caused not only by increasing the linear energy transfer (LET) of beam particles with the penetration depth towards the Bragg peak, but also by nuclear reactions induced by beam nuclei leading to the production of various secondary particles. Although the changes of RBE along the beam axis have been studied quite well, much less attention has been paid to the evolution of RBE in the transverse direction, perpendicular to the beam axis. In order to fill this gap, we simulated radiation fields of (1)H, (4)He, (12)C and (16)O nuclei of 20 mm in diameter by means of a Geant4-based Monte Carlo model for heavy-ion therapy connected with the modified microdosimetric kinetic model to describe the response of normal ([Formula: see text] Gy) and early-responding ([Formula: see text] Gy) tissues. Depth and radial distributions of saturation-corrected dose-mean lineal energy, RBE and RBE-weighted dose are investigated for passive beam shaping and active beam scanning. The field of (4)He has a small lateral spread as compared with (1)H field, and it is characterised by a modest lateral variation of RBE suggesting the use of fixed RBE values across the field transverse cross section at each depth. Reduced uncertainties of RBE on the boundary of a (4)He treatment field can be advantageous in a specific case of an organ at risk located in lateral proximity to the target volume. It is found that the lateral distributions of RBE calculated for (12)C and (16)O fields demonstrate fast variations in the radial direction due to changes of dose and composition of secondary fragments in the field penumbra. Nevertheless, the radiation fields of all four projectiles at radii larger than 20 mm can be characterized by a common RBE value defined by tissue radiosensitivity. These findings can help, in particular, in accessing

  5. Lateral variations of radiobiological properties of therapeutic fields of 1H, 4He, 12C and 16O ions studied with Geant4 and microdosimetric kinetic model

    NASA Astrophysics Data System (ADS)

    Dewey, Sophie; Burigo, Lucas; Pshenichnov, Igor; Mishustin, Igor; Bleicher, Marcus

    2017-07-01

    As known, in cancer therapy with ion beams the relative biological effectiveness (RBE) of ions changes in the course of their propagation in tissues. Such changes are caused not only by increasing the linear energy transfer (LET) of beam particles with the penetration depth towards the Bragg peak, but also by nuclear reactions induced by beam nuclei leading to the production of various secondary particles. Although the changes of RBE along the beam axis have been studied quite well, much less attention has been paid to the evolution of RBE in the transverse direction, perpendicular to the beam axis. In order to fill this gap, we simulated radiation fields of 1H, 4He, 12C and 16O nuclei of 20 mm in diameter by means of a Geant4-based Monte Carlo model for heavy-ion therapy connected with the modified microdosimetric kinetic model to describe the response of normal ((α/β)_x-rays=3.8 Gy) and early-responding ((α/β)_x-rays=10 Gy) tissues. Depth and radial distributions of saturation-corrected dose-mean lineal energy, RBE and RBE-weighted dose are investigated for passive beam shaping and active beam scanning. The field of 4He has a small lateral spread as compared with 1H field, and it is characterised by a modest lateral variation of RBE suggesting the use of fixed RBE values across the field transverse cross section at each depth. Reduced uncertainties of RBE on the boundary of a 4He treatment field can be advantageous in a specific case of an organ at risk located in lateral proximity to the target volume. It is found that the lateral distributions of RBE calculated for 12C and 16O fields demonstrate fast variations in the radial direction due to changes of dose and composition of secondary fragments in the field penumbra. Nevertheless, the radiation fields of all four projectiles at radii larger than 20 mm can be characterized by a common RBE value defined by tissue radiosensitivity. These findings can help, in particular, in accessing the transverse

  6. Assessment of Geant4 Prompt-Gamma Emission Yields in the Context of Proton Therapy Monitoring

    PubMed Central

    Pinto, Marco; Dauvergne, Denis; Freud, Nicolas; Krimmer, Jochen; Létang, Jean M.; Testa, Etienne

    2016-01-01

    Monte Carlo tools have been long used to assist the research and development of solutions for proton therapy monitoring. The present work focuses on the prompt-gamma emission yields by comparing experimental data with the outcomes of the current version of Geant4 using all applicable proton inelastic models. For the case in study and using the binary cascade model, it was found that Geant4 overestimates the prompt-gamma emission yields by 40.2 ± 0.3%, even though it predicts the prompt-gamma profile length of the experimental profile accurately. In addition, the default implementations of all proton inelastic models show an overestimation in the number of prompt gammas emitted. Finally, a set of built-in options and physically sound Geant4 source code changes have been tested in order to try to improve the discrepancy observed. A satisfactory agreement was found when using the QMD model with a wave packet width equal to 1.3 fm2. PMID:26858937

  7. Assessment of Geant4 Prompt-Gamma Emission Yields in the Context of Proton Therapy Monitoring.

    PubMed

    Pinto, Marco; Dauvergne, Denis; Freud, Nicolas; Krimmer, Jochen; Létang, Jean M; Testa, Etienne

    2016-01-01

    Monte Carlo tools have been long used to assist the research and development of solutions for proton therapy monitoring. The present work focuses on the prompt-gamma emission yields by comparing experimental data with the outcomes of the current version of Geant4 using all applicable proton inelastic models. For the case in study and using the binary cascade model, it was found that Geant4 overestimates the prompt-gamma emission yields by 40.2 ± 0.3%, even though it predicts the prompt-gamma profile length of the experimental profile accurately. In addition, the default implementations of all proton inelastic models show an overestimation in the number of prompt gammas emitted. Finally, a set of built-in options and physically sound Geant4 source code changes have been tested in order to try to improve the discrepancy observed. A satisfactory agreement was found when using the QMD model with a wave packet width equal to 1.3 fm(2).

  8. A macroscopic and microscopic study of radon exposure using Geant4 and MCNPX to estimate dose rates and DNA damage

    NASA Astrophysics Data System (ADS)

    van den Akker, Mary Evelyn

    Radon is considered the second-leading cause of lung cancer after smoking. Epidemiological studies have been conducted in miner cohorts as well as general populations to estimate the risks associated with high and low dose exposures. There are problems with extrapolating risk estimates to low dose exposures, mainly that the dose-response curve at low doses is not well understood. Calculated dosimetric quantities give average energy depositions in an organ or a whole body, but morphological features of an individual can affect these values. As opposed to human phantom models, Computed Tomography (CT) scans provide unique, patient-specific geometries that are valuable in modeling the radiological effects of the short-lived radon progeny sources. Monte Carlo particle transport code Geant4 was used with the CT scan data to model radon inhalation in the main bronchial bifurcation. The equivalent dose rates are near the lower bounds of estimates found in the literature, depending on source volume. To complement the macroscopic study, simulations were run in a small tissue volume in Geant4-DNA toolkit. As an expansion of Geant4 meant to simulate direct physical interactions at the cellular level, the particle track structure of the radon progeny alphas can be analyzed to estimate the damage that can occur in sensitive cellular structures like the DNA molecule. These estimates of DNA double strand breaks are lower than those found in Geant4-DNA studies. Further refinements of the microscopic model are at the cutting edge of nanodosimetry research.

  9. SU-E-T-521: Investigation of the Uncertainties Involved in Secondary Neutron/gamma Production in Geant4/MCNP6 Monte Carlo Codes for Proton Therapy Application

    SciTech Connect

    Mirzakhanian, L; Enger, S; Giusti, V

    2015-06-15

    Purpose: A major concern in proton therapy is the production of secondary neutrons causing secondary cancers, especially in young adults and children. Most utilized Monte Carlo codes in proton therapy are Geant4 and MCNP. However, the default versions of Geant4 and MCNP6 do not have suitable cross sections or physical models to properly handle secondary particle production in proton energy ranges used for therapy. In this study, default versions of Geant4 and MCNP6 were modified to better handle production of secondaries by adding the TENDL-2012 cross-section library. Methods: In-water proton depth-dose was measured at the “The Svedberg Laboratory” in Uppsala (Sweden). The proton beam was mono-energetic with mean energy of 178.25±0.2 MeV. The measurement set-up was simulated by Geant4 version 10.00 (default and modified version) and MCNP6. Proton depth-dose, primary and secondary particle fluence and neutron equivalent dose were calculated. In case of Geant4, the secondary particle fluence was filtered by all the physics processes to identify the main process responsible for the difference between the default and modified version. Results: The proton depth-dose curves and primary proton fluence show a good agreement between both Geant4 versions and MCNP6. With respect to the modified version, default Geant4 underestimates the production of secondary neutrons while overestimates that of gammas. The “ProtonInElastic” process was identified as the main responsible process for the difference between the two versions. MCNP6 shows higher neutron production and lower gamma production than both Geant4 versions. Conclusion: Despite the good agreement on the proton depth dose curve and primary proton fluence, there is a significant discrepancy on secondary neutron production between MCNP6 and both versions of Geant4. Further studies are thus in order to find the possible cause of this discrepancy or more accurate cross-sections/models to handle the nuclear

  10. Alpha Coincidence Spectroscopy studied with GEANT4

    SciTech Connect

    Dion, Michael P.; Miller, Brian W.; Tatishvili, Gocha; Warren, Glen A.

    2013-11-02

    Abstract The high-energy side of peaks in alpha spectra, e.g. 241Am, as measured with a silicon detector has structure caused mainly by alpha-conversion electron and to some extent alphagamma coincidences. We compare GEANT4 simulation results to 241Am alpha spectroscopy measurements with a passivated implanted planar silicon detector. A large discrepancy between the measurements and simulations suggest that the GEANT4 photon evaporation database for 237Np (daughter of 241Am decay) does not accurately describe the conversion electron spectrum and therefore was found to have large discrepancies with experimental measurements. We describe how to improve the agreement between GEANT4 and alpha spectroscopy for actinides of interest by including experimental measurements of conversion electron spectroscopy into the photon evaporation database.

  11. Simulations of an X-Ray Detector Using Geant4

    NASA Astrophysics Data System (ADS)

    Ertley, Camden; McConnell, Mark; Bloser, Peter; Legere, Jason; Connor, Taylor; Ryan, James

    2009-10-01

    NASA's Black Hole Finder Probe mission has two proposed concepts. CASTER, one of the proposed concepts, is a scintillator based Coded Aperture Survey Telescope for Energetic Radiation. This paper focuses on the development of a simulation that accurately models the proposed CASTER detector. The current detector design consists of a Lanthanum Bromide (LaBr3) scintillator directly coupled to a multianode photomultiplier tube (MAPMT). This detector should be optimized to give the best energy and position resolution. The simulation is based on the Geant4 toolkit, a set of detector simulation tools developed at CERN. Geant4 was chosen because it accurately models radiation devices and detectors, while allowing the simulation of transport and boundary conditions of optical photons. The results of the simulation were compared with data taken in the lab with a ^57Co and an ^241Am source. Once validated, the simulations will be used to optimize the final detector design.

  12. Accurate simulations of TEPC neutron spectra using Geant4

    NASA Astrophysics Data System (ADS)

    Taylor, G. C.; Hawkes, N. P.; Shippen, A.

    2015-11-01

    A Geant4 model of a tissue-equivalent proportional counter (TEPC) has been developed in which the calculated output spectrum exhibits unparalleled agreement with experiment for monoenergetic neutron fields at several energies below 20 MeV. The model uses the standard release of the Geant4 9.6 p2 code, but with a non-standard neutron cross section file as provided by Mendoza et al., and with the environment variable options recommended by the same authors. This configuration was found to produce significant improvements in the alpha-dominated region of the calculated response. In this paper, these improvements are presented, and the post-processing required to convert deposited energy into the number of ion pairs (which is the quantity actually measured experimentally) is discussed.

  13. Comparison of experimental proton-induced fluorescence spectra for a selection of thin high-Z samples with Geant4 Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Incerti, S.; Barberet, Ph.; Dévès, G.; Michelet, C.; Francis, Z.; Ivantchenko, V.; Mantero, A.; El Bitar, Z.; Bernal, M. A.; Tran, H. N.; Karamitros, M.; Seznec, H.

    2015-09-01

    The general purpose Geant4 Monte Carlo simulation toolkit is able to simulate radiative and non-radiative atomic de-excitation processes such as fluorescence and Auger electron emission, occurring after interaction of incident ionising radiation with target atomic electrons. In this paper, we evaluate the Geant4 modelling capability for the simulation of fluorescence spectra induced by 1.5 MeV proton irradiation of thin high-Z foils (Fe, GdF3, Pt, Au) with potential interest for nanotechnologies and life sciences. Simulation results are compared to measurements performed at the Centre d'Etudes Nucléaires de Bordeaux-Gradignan AIFIRA nanobeam line irradiation facility in France. Simulation and experimental conditions are described and the influence of Geant4 electromagnetic physics models is discussed.

  14. GEANT4 Simulation of Hadronic Interactions at 8-GeV/C to 10-GeV/C: Response to the HARP-CDP Group

    SciTech Connect

    Uzhinsky, V.; Apostolakis, J.; Folger, G.; Ivanchenko, V.N.; Kossov, M.V.; Wright, D.H.; /SLAC

    2011-11-21

    The results of the HARP-CDP group on the comparison of GEANT4 Monte Carlo predictions versus experimental data are discussed. It is shown that the problems observed by the group are caused by an incorrect implementation of old features at the programming level, and by a lack of the nucleon Fermi motion in the simulation of quasielastic scattering. These drawbacks are not due to the physical models used. They do not manifest themselves in the most important applications of the GEANT4 toolkit.

  15. Using Geant4 in the BaBar Simulation

    SciTech Connect

    Wright, Dennis H

    2003-05-23

    BABAR was the first large experiment to incorporate Geant4 into its detector simulation. Since July 2001, 1.5 x 10{sup 9} BABAR events have been produced using this simulation. In a typical e{sup +}e{sup -} {yields} {Upsilon} (4s) {yields} B{sup 0}{bar B}{sup 0} event, between 30 and 60 tracks are produced in the generator and propagated through the detector, using decay, electromagnetic and hadronic processes provided by the Geant4 toolkit. The material model of the detector is very detailed and a special particle transportation module was developed so that minute features (on the few micron scale) would be sampled in the propagation without sacrificing performance. The propagation phase for such an event requires 5 CPU seconds on an 866 MHz processor. Execution speeds for other BABAR event types will also be presented. Validation of simulated events with BABAR data is ongoing, and results of Monte Carlo/data comparisons will be shown. A discussion of the design of the simulation code, how the Geant4 toolkit is used, and ongoing efforts to improve the agreement between data and Monte Carlo will also be presented.

  16. Validation of the GEANT4 simulation of bremsstrahlung from thick targets below 3 MeV

    NASA Astrophysics Data System (ADS)

    Pandola, L.; Andenna, C.; Caccia, B.

    2015-05-01

    The bremsstrahlung spectra produced by electrons impinging on thick targets are simulated using the GEANT4 Monte Carlo toolkit. Simulations are validated against experimental data available in literature for a range of energy between 0.5 and 2.8 MeV for Al and Fe targets and for a value of energy of 70 keV for Al, Ag, W and Pb targets. The energy spectra for the different configurations of emission angles, energies and targets are considered. Simulations are performed by using the three alternative sets of electromagnetic models that are available in GEANT4 to describe bremsstrahlung. At higher energies (0.5-2.8 MeV) of the impinging electrons on Al and Fe targets, GEANT4 is able to reproduce the spectral shapes and the integral photon emission in the forward direction. The agreement is within 10-30%, depending on energy, emission angle and target material. The physics model based on the Penelope Monte Carlo code is in slightly better agreement with the measured data than the other two. However, all models over-estimate the photon emission in the backward hemisphere. For the lower energy study (70 keV), which includes higher-Z targets, all models systematically under-estimate the total photon yield, providing agreement between 10% and 50%. The results of this work are of potential interest for medical physics applications, where knowledge of the energy spectra and angular distributions of photons is needed for accurate dose calculations with Monte Carlo and other fluence-based methods.

  17. GEANT4 for breast dosimetry: parameters optimization study

    NASA Astrophysics Data System (ADS)

    Fedon, C.; Longo, F.; Mettivier, G.; Longo, R.

    2015-08-01

    Mean glandular dose (MGD) is the main dosimetric quantity in mammography. MGD evaluation is obtained by multiplying the entrance skin air kerma (ESAK) by normalized glandular dose (DgN) coefficients. While ESAK is an empirical quantity, DgN coefficients can only be estimated with Monte Carlo (MC) methods. Thus, a MC parameters benchmark is needed for effectively evaluating DgN coefficients. GEANT4 is a MC toolkit suitable for medical purposes that offers to the users several computational choices. In this work we investigate the GEANT4 performances testing the main PhysicsLists for medical applications. Four electromagnetic PhysicsLists were implemented: the linear attenuation coefficients were calculated for breast glandularity 0%, 50%, 100% in the energetic range 8-50 keV and DgN coefficients were evaluated. The results were compared with published data. Fit equations for the estimation of the G-factor parameter, introduced by the literature for converting the dose delivered in the heterogeneous medium to that in the glandular tissue, are proposed and the application of this parameter interaction-by-interaction or retrospectively is discussed. G4EmLivermorePhysicsList shows the best agreement for the linear attenuation coefficients both with theoretical values and published data. Moreover, excellent correlation factor ({{r}2}>0.99 ) is found for the DgN coefficients with the literature. The final goal of this study is to identify, for the first time, a benchmark of parameters that could be useful for future breast dosimetry studies with GEANT4.

  18. Geant4: A Simulation Toolkit for the Passage of Particles through Matter

    NASA Astrophysics Data System (ADS)

    Geant4 Collaboration

    2010-10-01

    Geant4 is a toolkit for simulating the passage of particles through matter. It includes a complete range of functionality including tracking, geometry, physics models and hits. The physics processes offered cover a comprehensive range, including electromagnetic, hadronic and optical processes, a large set of long-lived particles, materials and elements, over a wide energy range starting, in some cases, from 250eV and extending in others to the TeV energy range. It has been designed and constructed to expose the physics models utilised, to handle complex geometries, and to enable its easy adaptation for optimal use in different sets of applications. The toolkit is the result of a worldwide collaboration of physicists and software engineers. It has been created exploiting software engineering and object-oriented technology and implemented in the C++ programming language. It has been used in applications in particle physics, nuclear physics, accelerator design, space engineering and medical physics.

  19. Benchmarking GATE/Geant4 for (16)O ion beam therapy.

    PubMed

    Resch, Andreas F; Fuchs, Hermann; Georg, Dietmar

    2017-09-05

    Oxygen ([Formula: see text]) ions are a potential alternative to carbon ions in ion beam therapy. Their enhanced linear energy transfer indicates a higher relative biological effectiveness and a reduced oxygen enhancement ratio. Due to the limited availability of [Formula: see text] ion beams, Monte Carlo (MC) transport codes are important research tools for investigating their potential. The purpose of this study was to validate GATE/Geant4 for [Formula: see text] ion beam therapy using experimental data from literature. Five hadron physics lists and two electromagnetic options were benchmarked against measured depth dose distributions (DDDs) and charge-changing cross sections. The simulated beam ranges deviated by less than 0.5% for all physics configurations and only a few points exceeded the gamma index criterion (2%/1 mm). However, the simulated partial charge-changing cross sections deviated considerably for some hadron physics configurations. Best agreement with the experimental values was obtained with the quantum molecular dynamics model (QMD), and we therefore suggest using this model in Geant4 to accurately describe the fragmentation of [Formula: see text] ion beams into lighter fragments ([Formula: see text]).

  20. GEANT4 simulation of cyclotron radioisotope production in a solid target.

    PubMed

    Poignant, F; Penfold, S; Asp, J; Takhar, P; Jackson, P

    2016-05-01

    The use of radioisotopes in nuclear medicine is essential for diagnosing and treating cancer. The optimization of their production is a key factor in maximizing the production yield and minimizing the associated costs. An efficient approach to this problem is the use of Monte Carlo simulations prior to experimentation. By predicting isotopes yields, one can study the isotope of interest expected activity for different energy ranges. One can also study the target contamination with other radioisotopes, especially undesired radioisotopes of the wanted chemical element which are difficult to separate from the irradiated target and might result in increasing the dose when delivering the radiopharmaceutical product to the patient. The aim of this work is to build and validate a Monte Carlo simulation platform using the GEANT4 toolkit to model the solid target system of the South Australian Health and Medical Research Institute (SAHMRI) GE Healthcare PETtrace cyclotron. It includes a GEANT4 Graphical User Interface (GUI) where the user can modify simulation parameters such as the energy, shape and current of the proton beam, the target geometry and material, the foil geometry and material and the time of irradiation. The paper describes the simulation and presents a comparison of simulated and experimental/theoretical yields for various nuclear reactions on an enriched nickel 64 target using the GEANT4 physics model QGSP_BIC_AllHP, a model recently developed to evaluate with high precision the interaction of protons with energies below 200MeV available in Geant4 version 10.1. The simulation yield of the (64)Ni(p,n)(64)Cu reaction was found to be 7.67±0.074 mCi·μA(-1) for a target energy range of 9-12MeV. Szelecsenyi et al. (1993) gives a theoretical yield of 6.71mCi·μA(-1) and an experimental yield of 6.38mCi·μA(-1). The (64)Ni(p,n)(64)Cu cross section obtained with the simulation was also verified against the yield predicted from the nuclear database TENDL and

  1. Experimental test of Monte Carlo proton transport at grazing incidence in GEANT4, FLUKA and MCNPX

    NASA Astrophysics Data System (ADS)

    Kimstrand, Peter; Tilly, Nina; Ahnesjö, Anders; Traneus, Erik

    2008-02-01

    The ability of the Monte Carlo (MC) particle transport codes GEANT4.8.1 and GEANT4.8.2, FLUKA2006 and MCNPX2.4.0 to model proton transport at grazing incidence onto tungsten blocks has been tested and compared to experimental measurements. The test geometry consisted of a narrow proton beam of two energies, 98 MeV and 180 MeV, impinging on a thick tungsten alloy block at grazing incidence. The distribution of forward out-scatter from the tungsten alloy block was measured with a fluorescent screen viewed with a CCD camera via a mirror. In the MC simulations, the experimental setup was modelled and the dose deposited to the fluorescent screen material was scored. Simulations and measurements were made for four different incidence angles (3.5, 5.0, 7.5 and 10°). Several different sets of calculations were performed, studying the impact of different user-defined settings in the different MC packages. The study of different parameters settings in the GEANT4.8.1 simulation showed a strong dependence of the calculated out-scatter probability on the maximum allowed step length. For the largest incidence angle an increase of 60% in the out-scatter probability was found when restricting the maximum allowed step length to 0.05 cm. We also observed that the stepping algorithm of GEANT4.8.1 and 4.8.2 introduces a small non-physical directional and positional asymmetry at the exit boundary of the tungsten alloy block. The shape of the energy spectrum of protons being out-scattered agreed between the codes. The dose-weighted forward out-scatter probability, i.e. the ratio between the total signal from the unscattered beam and the out-scattered beam, showed a qualitative agreement of simulations compared to measurements. Quantitatively, the deviation of the simulations reached as high as 37%, while the experimental uncertainty was 14%. The mean emission angle of the simulations was within 16% of the measurement for all incidence angles with a measurement uncertainty of 8%.

  2. Geometry Optimization in NOvA with Geant4

    NASA Astrophysics Data System (ADS)

    Nguyen, Vivan; Messier, Mark; NOvA Collaboration

    2013-10-01

    NOvA is a neutrino beam experiment, designed to detect neutrino oscillations. There are two detectors, placed at distances of 1km and 810 km from the proton target. The detectors are made of PVC filled with liquid scintillator. In simulating the experiment, an important aspect is the detector geometry, which is input to Geant4 using the GDML markup language. I will present studies in which the geometry description was systematically varied to find a configuration which preserved the modeling accuracy required by the experiment while minimizing the CPU time required for the simulation. This work was supported by the REU Program of the National Science Foundation under Award PHY-1156540.

  3. Validation of Geant4 on Proton Transportation for Thick Absorbers: Study Based on Tschalär Experimental Data

    NASA Astrophysics Data System (ADS)

    Hoff, Gabriela; Denyak, Valeriy; Schelin, Hugo R.; Paschuk, Sergei

    2017-02-01

    Imaging techniques using protons as incident particles are currently being developed to substitute X-ray computer tomography and nuclear magnetic resonance methods in proton therapy. They deal with relatively thick targets, like the human head or trunk, where protons lose a significant part of their energy, however, they have enough energy to exit the target. The physical quantities important in proton imaging are kinetic energy, angle and coordinates of emerging proton from an absorber material. In recent times, many research groups use the Geant4 toolkit to simulate proton imaging devices. Most of the available publications about validation of Geant4 models are for thin or thick absorbers (Bragg Peak studies), that are not consistent with the contour conditions applied to proton imaging. The main objective of this work is to evaluate the kinetic energy spectrum for protons emerging from homogeneous absorbers slabs comparing it to the experimental results published by Tschalär and Maccabee, in 1970. Different models (standard and detailed) available on Geant4 (version 9.6.p03) are explored taking into account its accuracy and computational performance. This paper presents a validation for protons with incident kinetic energies of 19.68 MeV and 49.10 MeV. The validation results from the emerging protons kinetic energy spectra show that: (i) there are differences between the reference data and the data produced by different processes evoked for transportation and (ii) the validation energies are sensitive to sub-shell processes.

  4. Simulation of early DNA damage after the irradiation of a fibroblast cell nucleus using Geant4-DNA.

    PubMed

    Meylan, Sylvain; Incerti, Sébastien; Karamitros, Mathieu; Tang, Nicolas; Bueno, Marta; Clairand, Isabelle; Villagrasa, Carmen

    2017-09-20

    In order to improve the understanding of the mechanisms involved in the generation of early DNA damage, a new calculation chain based on the Geant4-DNA toolkit was developed. This work presents for the first time the simulation of the physical, physicochemical and chemical stages of early radiation damage at the scale of an entire human genome (fibroblast, male) and using Geant4-DNA models. The DnaFabric software was extended to generate and export this nucleus model to a text file with a specific format that can be read by Geant4 user applications. This calculation chain was used to simulate the irradiation of the nucleus by primary protons of different energies (0,5; 0,7; 0,8; 1; 1,5; 2; 3; 4; 5; 10; 20 MeV) and the results, in terms of DNA double strand breaks, agree with experimental data found in the literature (pulsed field electrophoresis technique). These results show that the simulation is consistent and that its parameters are well balanced. Among the different parameters that can be adjusted, our results demonstrate that the criterion used to select direct strand break appears to have a very significant role on the final number of simulated double strand breaks.

  5. Application of dynamic Monte Carlo technique in proton beam radiotherapy using Geant4 simulation toolkit

    NASA Astrophysics Data System (ADS)

    Guan, Fada

    Monte Carlo method has been successfully applied in simulating the particles transport problems. Most of the Monte Carlo simulation tools are static and they can only be used to perform the static simulations for the problems with fixed physics and geometry settings. Proton therapy is a dynamic treatment technique in the clinical application. In this research, we developed a method to perform the dynamic Monte Carlo simulation of proton therapy using Geant4 simulation toolkit. A passive-scattering treatment nozzle equipped with a rotating range modulation wheel was modeled in this research. One important application of the Monte Carlo simulation is to predict the spatial dose distribution in the target geometry. For simplification, a mathematical model of a human body is usually used as the target, but only the average dose over the whole organ or tissue can be obtained rather than the accurate spatial dose distribution. In this research, we developed a method using MATLAB to convert the medical images of a patient from CT scanning into the patient voxel geometry. Hence, if the patient voxel geometry is used as the target in the Monte Carlo simulation, the accurate spatial dose distribution in the target can be obtained. A data analysis tool---root was used to score the simulation results during a Geant4 simulation and to analyze the data and plot results after simulation. Finally, we successfully obtained the accurate spatial dose distribution in part of a human body after treating a patient with prostate cancer using proton therapy.

  6. Integration of g4tools in Geant4

    NASA Astrophysics Data System (ADS)

    Hřivnáčová, Ivana

    2014-06-01

    g4tools, that is originally part of the inlib and exlib packages, provides a very light and easy to install set of C++ classes that can be used to perform analysis in a Geant4 batch program. It allows to create and manipulate histograms and ntuples, and write them in supported file formats (ROOT, AIDA XML, CSV and HBOOK). It is integrated in Geant4 through analysis manager classes, thus providing a uniform interface to the g4tools objects and also hiding the differences between the classes for different supported output formats. Moreover, additional features, such as for example histogram activation or support for Geant4 units, are implemented in the analysis classes following users requests. A set of Geant4 user interface commands allows the user to create histograms and set their properties interactively or in Geant4 macros. g4tools was first introduced in the Geant4 9.5 release where its use was demonstrated in one basic example, and it is already used in a majority of the Geant4 examples within the Geant4 9.6 release. In this paper, we will give an overview and the present status of the integration of g4tools in Geant4 and report on upcoming new features.

  7. Geant4 supplied parameters for gamma reaction history at NIF

    NASA Astrophysics Data System (ADS)

    Rubery, Michael; Horsfield, Colin; Herrmann, Hans; Kim, Yongho; Mack, Joe; Young, Carl; Evans, Scott; Sedillo, Tom; Miller, Kirk; Stoeffl, Wolfgang; Grafil, Elliot

    2011-10-01

    The GRH diagnostics at NIF and Omega report ICF burn parameters through detection of multi-MeV γ emissions. Of particular interest is ` γ bang-time' (GBT), defined as the temporal separation between light impacting the capsule and peak in the nuclear reaction history; GBT can constrain shock and compression parameters, and indicate fuel/ablator mix. Early NIF commissioning experiments have identified contributions to GRH signals from n,n' γ reactions with remaining capsule ablator, hohlraum and thermo-mechanical package, outside the fuel hotspot region. Such contributions are mitigated by increasing the Cherenkov threshold above the energy of these emissions. The pressure adjustment modifies parameters important to GBT, such as cell time-of-flight and detector FWHM; corrections simulated using Geant4 are presented using models experimentally validated at Duke University. Beyond GBT, studies suggest GRH may be capable of recording ablator ρR, unfolding the DT γ spectrum, and inferring the DTγ /DTn branching ratio. All calculations rely on the energy-resolved intensity response as a function of gas pressure. Geant4 response simulations, together with calculations by LANL using the experimentally validated ACCEPT code, are also presented.

  8. geant4 hadronic cascade models analysis of proton and charged pion transverse momentum spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c

    SciTech Connect

    Abdel-Waged, Khaled; Felemban, Nuha; Uzhinskii, V. V.

    2011-07-15

    We describe how various hadronic cascade models, which are implemented in the geant4 toolkit, describe proton and charged pion transverse momentum spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c, recently measured in the hadron production (HARP) experiment at CERN. The Binary, ultrarelativistic quantum molecular dynamics (UrQMD) and modified FRITIOF (FTF) hadronic cascade models are chosen for investigation. The first two models are based on limited (Binary) and branched (UrQMD) binary scattering between cascade particles which can be either a baryon or meson, in the three-dimensional space of the nucleus, while the latter (FTF) considers collective interactions between nucleons only, on the plane of impact parameter. It is found that the slow (p{sub T}{<=}0.3 GeV/c) proton spectra are quite sensitive to the different treatments of cascade pictures, while the fast (p{sub T}>0.3 GeV/c) proton spectra are not strongly affected by the differences between the FTF and UrQMD models. It is also shown that the UrQMD and FTF combined with Binary (FTFB) models could reproduce both proton and charged pion spectra from p + Cu and Pb collisions at 3, 8, and 15 GeV/c with the same accuracy.

  9. Behaviors of the percentage depth dose curves along the beam axis of a phantom filled with different clinical PTO objects, a Monte Carlo Geant4 study

    NASA Astrophysics Data System (ADS)

    EL Bakkali, Jaafar; EL Bardouni, Tarek; Safavi, Seyedmostafa; Mohammed, Maged; Saeed, Mroan

    2016-08-01

    The aim of this work is to assess the capabilities of Monte Carlo Geant4 code to reproduce the real percentage depth dose (PDD) curves generated in phantoms which mimic three important clinical treatment situations that include lung slab, bone slab, bone-lung slab geometries. It is hoped that this work will lead us to a better understanding of dose distributions in an inhomogeneous medium, and to identify any limitations of dose calculation algorithm implemented in the Geant4 code. For this purpose, the PDD dosimetric functions associated to the three clinical situations described above, were compared to one produced in a homogeneous water phantom. Our results show, firstly, that the Geant4 simulation shows potential mistakes on the shape of the calculated PDD curve of the first physical test object (PTO), and it is obviously not able to successfully predict dose values in regions near to the boundaries between two different materials. This is, surely due to the electron transport algorithm and it is well-known as the artifacts at interface phenomenon. To deal with this issue, we have added and optimized the StepMax parameter to the dose calculation program; consequently the artifacts due to the electron transport were quasi disappeared. However, the Geant4 simulation becomes painfully slow when we attempt to completely resolve the electron artifact problems by considering a smaller value of an electron StepMax parameter. After electron transport optimization, our results demonstrate the medium-level capabilities of the Geant4 code to modeling dose distribution in clinical PTO objects.

  10. SU-E-T-347: Validation of the Condensed History Algorithm of Geant4 Using the Fano Test

    SciTech Connect

    Lee, H; Mathis, M; Sawakuchi, G

    2014-06-01

    Purpose: To validate the condensed history algorithm and physics of the Geant4 Monte Carlo toolkit for simulations of ionization chambers (ICs). This study is the first step to validate Geant4 for calculations of photon beam quality correction factors under the presence of a strong magnetic field for magnetic resonance guided linac system applications. Methods: The electron transport and boundary crossing algorithms of Geant4 version 9.6.p02 were tested under Fano conditions using the Geant4 example/application FanoCavity. User-defined parameters of the condensed history and multiple scattering algorithms were investigated under Fano test conditions for three scattering models (physics lists): G4UrbanMscModel95 (PhysListEmStandard-option3), G4GoudsmitSaundersonMsc (PhysListEmStandard-GS), and G4WentzelVIModel/G4CoulombScattering (PhysListEmStandard-WVI). Simulations were conducted using monoenergetic photon beams, ranging from 0.5 to 7 MeV and emphasizing energies from 0.8 to 3 MeV. Results: The GS and WVI physics lists provided consistent Fano test results (within ±0.5%) for maximum step sizes under 0.01 mm at 1.25 MeV, with improved performance at 3 MeV (within ±0.25%). The option3 physics list provided consistent Fano test results (within ±0.5%) for maximum step sizes above 1 mm. Optimal parameters for the option3 physics list were 10 km maximum step size with default values for other user-defined parameters: 0.2 dRoverRange, 0.01 mm final range, 0.04 range factor, 2.5 geometrical factor, and 1 skin. Simulations using the option3 physics list were ∼70 – 100 times faster compared to GS and WVI under optimal parameters. Conclusion: This work indicated that the option3 physics list passes the Fano test within ±0.5% when using a maximum step size of 10 km for energies suitable for IC calculations in a 6 MV spectrum without extensive computational times. Optimal user-defined parameters using the option3 physics list will be used in future IC simulations to

  11. CMS validation experience: Test-beam 2004 data vs GEANT4

    SciTech Connect

    Piperov, Stefan; /Fermilab /Sofiya, Inst. Nucl. Res.

    2007-01-01

    A comparison between the Geant4 Monte-Carlo simulation of CMS Detector's Calorimetric System and data from the 2004 Test-Beam at CERN's SPS H2 beam-line is presented. The overall simulated response agrees quite well with the measured response. Slight differences in the longitudinal shower profiles between the MC predictions made with different Physics Lists are observed.

  12. A Student Project to use Geant4 Simulations for a TMS-PET combination

    SciTech Connect

    Altamirano, A.; Chamorro, A.; Hurtado, K.; Romero, C.; Wahl, D.; Zamudio, A.; Rueda, A.; Solano Salinas, C. J.

    2007-10-26

    Geant4 is one of the most powerful tools for MC simulation of detectors and their applications. We present a student project to simulate a combined Transcranial Magnetic Stimulation-Positron Emission Tomography (TMS-PET) system using Geant4. This project aims to study PET-TMS systems by implementing a model for the brain response to the TMS pulse and studying the simulated PET response. In order to increase the speed of the simulations we parallelise our programs and investigate the possibility of using GRID computing.

  13. GEANT4 calculations of neutron dose in radiation protection using a homogeneous phantom and a Chinese hybrid male phantom.

    PubMed

    Geng, Changran; Tang, Xiaobin; Guan, Fada; Johns, Jesse; Vasudevan, Latha; Gong, Chunhui; Shu, Diyun; Chen, Da

    2016-03-01

    The purpose of this study is to verify the feasibility of applying GEANT4 (version 10.01) in neutron dose calculations in radiation protection by comparing the calculation results with MCNP5. The depth dose distributions are investigated in a homogeneous phantom, and the fluence-to-dose conversion coefficients are calculated for different organs in the Chinese hybrid male phantom for neutrons with energy ranging from 1 × 10(-9) to 10 MeV. By comparing the simulation results between GEANT4 and MCNP5, it is shown that using the high-precision (HP) neutron physics list, GEANT4 produces the closest simulation results to MCNP5. However, differences could be observed when the neutron energy is lower than 1 × 10(-6) MeV. Activating the thermal scattering with an S matrix correction in GEANT4 with HP and MCNP5 in thermal energy range can reduce the difference between these two codes.

  14. Geant4-based Monte Carlo simulations on GPU for medical applications.

    PubMed

    Bert, Julien; Perez-Ponce, Hector; El Bitar, Ziad; Jan, Sébastien; Boursier, Yannick; Vintache, Damien; Bonissent, Alain; Morel, Christian; Brasse, David; Visvikis, Dimitris

    2013-08-21

    Monte Carlo simulation (MCS) plays a key role in medical applications, especially for emission tomography and radiotherapy. However MCS is also associated with long calculation times that prevent its use in routine clinical practice. Recently, graphics processing units (GPU) became in many domains a low cost alternative for the acquisition of high computational power. The objective of this work was to develop an efficient framework for the implementation of MCS on GPU architectures. Geant4 was chosen as the MCS engine given the large variety of physics processes available for targeting different medical imaging and radiotherapy applications. In addition, Geant4 is the MCS engine behind GATE which is actually the most popular medical applications' simulation platform. We propose the definition of a global strategy and associated structures for such a GPU based simulation implementation. Different photon and electron physics effects are resolved on the fly directly on GPU without any approximations with respect to Geant4. Validations have shown equivalence in the underlying photon and electron physics processes between the Geant4 and the GPU codes with a speedup factor of 80-90. More clinically realistic simulations in emission and transmission imaging led to acceleration factors of 400-800 respectively compared to corresponding GATE simulations.

  15. Geant4-based Monte Carlo simulations on GPU for medical applications

    NASA Astrophysics Data System (ADS)

    Bert, Julien; Perez-Ponce, Hector; El Bitar, Ziad; Jan, Sébastien; Boursier, Yannick; Vintache, Damien; Bonissent, Alain; Morel, Christian; Brasse, David; Visvikis, Dimitris

    2013-08-01

    Monte Carlo simulation (MCS) plays a key role in medical applications, especially for emission tomography and radiotherapy. However MCS is also associated with long calculation times that prevent its use in routine clinical practice. Recently, graphics processing units (GPU) became in many domains a low cost alternative for the acquisition of high computational power. The objective of this work was to develop an efficient framework for the implementation of MCS on GPU architectures. Geant4 was chosen as the MCS engine given the large variety of physics processes available for targeting different medical imaging and radiotherapy applications. In addition, Geant4 is the MCS engine behind GATE which is actually the most popular medical applications' simulation platform. We propose the definition of a global strategy and associated structures for such a GPU based simulation implementation. Different photon and electron physics effects are resolved on the fly directly on GPU without any approximations with respect to Geant4. Validations have shown equivalence in the underlying photon and electron physics processes between the Geant4 and the GPU codes with a speedup factor of 80-90. More clinically realistic simulations in emission and transmission imaging led to acceleration factors of 400-800 respectively compared to corresponding GATE simulations.

  16. Monte Carlo calculations of thermal neutron capture in gadolinium: a comparison of GEANT4 and MCNP with measurements.

    PubMed

    Enger, Shirin A; Munck af Rosenschöld, Per; Rezaei, Arash; Lundqvist, Hans

    2006-02-01

    GEANT4 is a Monte Carlo code originally implemented for high-energy physics applications and is well known for particle transport at high energies. The capacity of GEANT4 to simulate neutron transport in the thermal energy region is not equally well known. The aim of this article is to compare MCNP, a code commonly used in low energy neutron transport calculations and GEANT4 with experimental results and select the suitable code for gadolinium neutron capture applications. To account for the thermal neutron scattering from chemically bound atoms [S(alpha,beta)] in biological materials a comparison of thermal neutron fluence in tissue-like poly(methylmethacrylate) phantom is made with MCNP4B, GEANT4 6.0 patch1, and measurements from the neutron capture therapy (NCT) facility at the Studsvik, Sweden. The fluence measurements agreed with MCNP calculated results considering S(alpha,beta). The location of the thermal neutron peak calculated with MCNP without S(alpha,beta) and GEANT4 is shifted by about 0.5 cm towards a shallower depth and is 25%-30% lower in amplitude. Dose distribution from the gadolinium neutron capture reaction is then simulated by MCNP and compared with measured data. The simulations made by MCNP agree well with experimental results. As long as thermal neutron scattering from chemically bound atoms are not included in GEANT4 it is not suitable for NCT applications.

  17. GGEMS-Brachy: GPU GEant4-based Monte Carlo simulation for brachytherapy applications

    NASA Astrophysics Data System (ADS)

    Lemaréchal, Yannick; Bert, Julien; Falconnet, Claire; Després, Philippe; Valeri, Antoine; Schick, Ulrike; Pradier, Olivier; Garcia, Marie-Paule; Boussion, Nicolas; Visvikis, Dimitris

    2015-07-01

    In brachytherapy, plans are routinely calculated using the AAPM TG43 formalism which considers the patient as a simple water object. An accurate modeling of the physical processes considering patient heterogeneity using Monte Carlo simulation (MCS) methods is currently too time-consuming and computationally demanding to be routinely used. In this work we implemented and evaluated an accurate and fast MCS on Graphics Processing Units (GPU) for brachytherapy low dose rate (LDR) applications. A previously proposed Geant4 based MCS framework implemented on GPU (GGEMS) was extended to include a hybrid GPU navigator, allowing navigation within voxelized patient specific images and analytically modeled 125I seeds used in LDR brachytherapy. In addition, dose scoring based on track length estimator including uncertainty calculations was incorporated. The implemented GGEMS-brachy platform was validated using a comparison with Geant4 simulations and reference datasets. Finally, a comparative dosimetry study based on the current clinical standard (TG43) and the proposed platform was performed on twelve prostate cancer patients undergoing LDR brachytherapy. Considering patient 3D CT volumes of 400  × 250  × 65 voxels and an average of 58 implanted seeds, the mean patient dosimetry study run time for a 2% dose uncertainty was 9.35 s (≈500 ms 10-6 simulated particles) and 2.5 s when using one and four GPUs, respectively. The performance of the proposed GGEMS-brachy platform allows envisaging the use of Monte Carlo simulation based dosimetry studies in brachytherapy compatible with clinical practice. Although the proposed platform was evaluated for prostate cancer, it is equally applicable to other LDR brachytherapy clinical applications. Future extensions will allow its application in high dose rate brachytherapy applications.

  18. Absorbed dose estimations of 131I for critical organs using the GEANT4 Monte Carlo simulation code

    NASA Astrophysics Data System (ADS)

    Ziaur, Rahman; Shakeel, ur Rehman; Waheed, Arshed; Nasir, M. Mirza; Abdul, Rashid; Jahan, Zeb

    2012-11-01

    The aim of this study is to compare the absorbed doses of critical organs of 131I using the MIRD (Medical Internal Radiation Dose) with the corresponding predictions made by GEANT4 simulations. S-values (mean absorbed dose rate per unit activity) and energy deposition per decay for critical organs of 131I for various ages, using standard cylindrical phantom comprising water and ICRP soft-tissue material, have also been estimated. In this study the effect of volume reduction of thyroid, during radiation therapy, on the calculation of absorbed dose is also being estimated using GEANT4. Photon specific energy deposition in the other organs of the neck, due to 131I decay in the thyroid organ, has also been estimated. The maximum relative difference of MIRD with the GEANT4 simulated results is 5.64% for an adult's critical organs of 131I. Excellent agreement was found between the results of water and ICRP soft tissue using the cylindrical model. S-values are tabulated for critical organs of 131I, using 1, 5, 10, 15 and 18 years (adults) individuals. S-values for a cylindrical thyroid of different sizes, having 3.07% relative differences of GEANT4 with Siegel & Stabin results. Comparison of the experimentally measured values at 0.5 and 1 m away from neck of the ionization chamber with GEANT4 based Monte Carlo simulations results show good agreement. This study shows that GEANT4 code is an important tool for the internal dosimetry calculations.

  19. artG4: A Generic Framework for Geant4 Simulations

    SciTech Connect

    Arvanitis, Tasha; Lyon, Adam

    2014-01-01

    A small experiment must devote its limited computing expertise to writing physics code directly applicable to the experiment. A software 'framework' is essential for providing an infrastructure that makes writing the physics-relevant code easy. In this paper, we describe a highly modular and easy to use framework for writing Geant4 based simulations called 'artg4'. This framework is a layer on top of the art framework.

  20. Validation of a small-animal PET simulation using GAMOS: a GEANT4-based framework

    NASA Astrophysics Data System (ADS)

    Cañadas, M.; Arce, P.; Rato Mendes, P.

    2011-01-01

    Monte Carlo-based modelling is a powerful tool to help in the design and optimization of positron emission tomography (PET) systems. The performance of these systems depends on several parameters, such as detector physical characteristics, shielding or electronics, whose effects can be studied on the basis of realistic simulated data. The aim of this paper is to validate a comprehensive study of the Raytest ClearPET small-animal PET scanner using a new Monte Carlo simulation platform which has been developed at CIEMAT (Madrid, Spain), called GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations). This toolkit, based on the GEANT4 code, was originally designed to cover multiple applications in the field of medical physics from radiotherapy to nuclear medicine, but has since been applied by some of its users in other fields of physics, such as neutron shielding, space physics, high energy physics, etc. Our simulation model includes the relevant characteristics of the ClearPET system, namely, the double layer of scintillator crystals in phoswich configuration, the rotating gantry, the presence of intrinsic radioactivity in the crystals or the storage of single events for an off-line coincidence sorting. Simulated results are contrasted with experimental acquisitions including studies of spatial resolution, sensitivity, scatter fraction and count rates in accordance with the National Electrical Manufacturers Association (NEMA) NU 4-2008 protocol. Spatial resolution results showed a discrepancy between simulated and measured values equal to 8.4% (with a maximum FWHM difference over all measurement directions of 0.5 mm). Sensitivity results differ less than 1% for a 250-750 keV energy window. Simulated and measured count rates agree well within a wide range of activities, including under electronic saturation of the system (the measured peak of total coincidences, for the mouse-sized phantom, was 250.8 kcps reached at 0.95 MBq mL-1 and the simulated peak was

  1. Extension of PENELOPE to protons: simulation of nuclear reactions and benchmark with Geant4.

    PubMed

    Sterpin, E; Sorriaux, J; Vynckier, S

    2013-11-01

    Describing the implementation of nuclear reactions in the extension of the Monte Carlo code (MC) PENELOPE to protons (PENH) and benchmarking with Geant4. PENH is based on mixed-simulation mechanics for both elastic and inelastic electromagnetic collisions (EM). The adopted differential cross sections for EM elastic collisions are calculated using the eikonal approximation with the Dirac-Hartree-Fock-Slater atomic potential. Cross sections for EM inelastic collisions are computed within the relativistic Born approximation, using the Sternheimer-Liljequist model of the generalized oscillator strength. Nuclear elastic and inelastic collisions were simulated using explicitly the scattering analysis interactive dialin database for (1)H and ICRU 63 data for (12)C, (14)N, (16)O, (31)P, and (40)Ca. Secondary protons, alphas, and deuterons were all simulated as protons, with the energy adapted to ensure consistent range. Prompt gamma emission can also be simulated upon user request. Simulations were performed in a water phantom with nuclear interactions switched off or on and integral depth-dose distributions were compared. Binary-cascade and precompound models were used for Geant4. Initial energies of 100 and 250 MeV were considered. For cases with no nuclear interactions simulated, additional simulations in a water phantom with tight resolution (1 mm in all directions) were performed with FLUKA. Finally, integral depth-dose distributions for a 250 MeV energy were computed with Geant4 and PENH in a homogeneous phantom with, first, ICRU striated muscle and, second, ICRU compact bone. For simulations with EM collisions only, integral depth-dose distributions were within 1%/1 mm for doses higher than 10% of the Bragg-peak dose. For central-axis depth-dose and lateral profiles in a phantom with tight resolution, there are significant deviations between Geant4 and PENH (up to 60%/1 cm for depth-dose distributions). The agreement is much better with FLUKA, with deviations within

  2. Simulation of Auger electron emission from nanometer-size gold targets using the Geant4 Monte Carlo simulation toolkit

    NASA Astrophysics Data System (ADS)

    Incerti, S.; Suerfu, B.; Xu, J.; Ivantchenko, V.; Mantero, A.; Brown, J. M. C.; Bernal, M. A.; Francis, Z.; Karamitros, M.; Tran, H. N.

    2016-04-01

    A revised atomic deexcitation framework for the Geant4 general purpose Monte Carlo toolkit capable of simulating full Auger deexcitation cascades was implemented in June 2015 release (version 10.2 Beta). An overview of this refined framework and testing of its capabilities is presented for the irradiation of gold nanoparticles (NP) with keV photon and MeV proton beams. The resultant energy spectra of secondary particles created within and that escape the NP are analyzed and discussed. It is anticipated that this new functionality will improve and increase the use of Geant4 in the medical physics, radiobiology, nanomedicine research and other low energy physics fields.

  3. Simulation of the production rates of cosmogenic nuclides on the Moon based on Geant4

    NASA Astrophysics Data System (ADS)

    Li, Yong; Zhang, Xiaoping; Dong, Wudong; Ren, Zhongzhou; Dong, Tiekuang; Xu, Aoao

    2017-02-01

    A numerical simulation model is built to simulate the production of cosmogenic nuclides based on Geant4 (GEometry ANd Tracking). Some modifications have been made for cross sections in Geant4 using the experimental data or the other proper model and the contributions of all secondary particles caused by cosmic rays are included in our simulation model. Our simulation results suggest a substantial contribution of the secondary charged pions to the production rates of 10Be and 14C, as high as 21.04% for 10Be and 21.36% for 14C, respectively. Within one set of self-consistent parameters, the simulation results of the production rates of the cosmogenic nuclides, 53Mn, 36Cl, 41Ca, 26Al, 10Be, and 14C, agree well with the measured data from Apollo 15 drill core. This model provides users a validated approach to study the production of cosmogenic nuclides on the planet surface and in the meteorites.

  4. Application of automated weight windows to spallation neutron source shielding calculations using Geant4

    NASA Astrophysics Data System (ADS)

    Stenander, John; DiJulio, Douglas D.

    2015-10-01

    We present an implementation of a general weight-window generator for global variance reduction in Geant4 based applications. The implementation is flexible and can be easily adjusted to a user-defined model. In this work, the weight-window generator was applied to calculations based on an instrument shielding model of the European Spallation Source, which is currently under construction in Lund, Sweden. The results and performance of the implemented methods were evaluated through the definition of two figures of merit. It was found that the biased simulations showed an overall improvement in performance compared to the unbiased simulations. The present work demonstrates both the suitability of the generator method and Geant4 for these types of calculations.

  5. Validation of Geant4 fragmentation for Heavy Ion Therapy

    NASA Astrophysics Data System (ADS)

    Bolst, David; Cirrone, Giuseppe A. P.; Cuttone, Giacomo; Folger, Gunter; Incerti, Sebastien; Ivanchenko, Vladimir; Koi, Tatsumi; Mancusi, Davide; Pandola, Luciano; Romano, Francesco; Rosenfeld, Anatoly B.; Guatelli, Susanna

    2017-10-01

    12C ion therapy has had growing interest in recent years for its excellent dose conformity. However at therapeutic energies, which can be as high as 400 MeV/u, carbon ions produce secondary fragments. For an incident 400 MeV/u 12C ion beam, ∼ 70 % of the beam will undergo fragmentation before the Bragg Peak. The dosimetric and radiobiological impact of these fragments must be accurately characterised, as it can result in increasing the risk of secondary cancer for the patient as well as altering the relative biological effectiveness. This work investigates the accuracy of three different nuclear fragmentation models available in the Monte Carlo Toolkit Geant4, the Binary Intranuclear Cascade (BIC), the Quantum Molecular Dynamics (QMD) and the Liege Intranuclear Cascade (INCL++). The models were benchmarked against experimental data for a pristine 400 MeV/u 12C beam incident upon a water phantom, including fragment yield, angular and energy distribution. For fragment yields the three alternative models agreed between ∼ 5 and ∼ 35 % with experimental measurements, the QMD using the ;Frag; option gave the best agreement for lighter fragments but had reduced agreement for larger fragments. For angular distributions INCL++ was seen to provide the best agreement among the models for all elements with the exception of Hydrogen, while BIC and QMD was seen to produce broader distributions compared to experiment. BIC and QMD performed similar to one another for kinetic energy distributions while INCL++ suffered from producing lower energy distributions compared to the other models and experiment.

  6. Geant4 simulation of the response of phosphor screens for X-ray imaging

    NASA Astrophysics Data System (ADS)

    Pistrui-Maximean, S. A.; Freud, N.; Létang, J. M.; Koch, A.; Munier, B.; Walenta, A. H.; Montarou, G.; Babot, D.

    2006-07-01

    In order to predict and optimize the response of phosphor screens, it is important to understand the role played by the different physical processes inside the scintillator layer. A simulation model based on the Monte Carlo code Geant4 was developed to determine the Modulation Transfer Function (MTF) of phosphor screens for energies used in X-ray medical imaging and nondestructive testing applications. The visualization of the dose distribution inside the phosphor layer gives an insight into how the MTF is progressively degraded by X-ray and electron transport. The simulation model allows to study the influence of physical and technological parameters on the detector performances, as well as to design and optimize new detector configurations. Preliminary MTF measurements have been carried out and agreement with experimental data has been found in the case of a commercial screen (Kodak Lanex Fine) at an X-ray tube potential of 100 kV. Further validation with other screens (transparent or granular) at different energies is under way.

  7. GEANT4 simulations of the n_TOF spallation source and their benchmarking

    NASA Astrophysics Data System (ADS)

    Lo Meo, S.; Cortés-Giraldo, M. A.; Massimi, C.; Lerendegui-Marco, J.; Barbagallo, M.; Colonna, N.; Guerrero, C.; Mancusi, D.; Mingrone, F.; Quesada, J. M.; Sabate-Gilarte, M.; Vannini, G.; Vlachoudis, V.

    2015-12-01

    Neutron production and transport in the spallation target of the n_TOF facility at CERN has been simulated with GEANT4. The results obtained with different models of high-energy nucleon-nucleus interaction have been compared with the measured characteristics of the neutron beam, in particular the flux and its dependence on neutron energy, measured in the first experimental area. The best agreement at present, within 20% for the absolute value of the flux, and within few percent for the energy dependence in the whole energy range from thermal to 1 GeV, is obtained with the INCL++ model coupled with the GEANT4 native de-excitation model. All other available models overestimate by a larger factor, of up to 70%, the n_TOF neutron flux. The simulations are also able to accurately reproduce the neutron beam energy resolution function, which is essentially determined by the moderation time inside the target/moderator assembly. The results here reported provide confidence on the use of GEANT4 for simulations of spallation neutron sources.

  8. Study of low energy neutron beam formation based on GEANT4 simulations

    NASA Astrophysics Data System (ADS)

    Avagyan, R.; Avetisyan, R.; Ivanyan, V.; Kerobyan, I.

    2017-07-01

    The possibility of obtaining thermal/epithermal energy neutron beams using external protons from cyclotron C18/18 is studied based on GEANT4 simulations. This study will be the basis of the Beam Shaped Assembly (BSA) development for future Boron Neutron Capture Therapy (BNCT). Proton induced reactions on 9Be target are considered as a neutron source, and dependence of neutron yield on target thickness is investigated. The problem of reducing the ratio of gamma to neutron yields by inserting a lead sheet after the beryllium target is studied as well. By GEANT4 modeling the optimal thicknesses of 9Be target and lead absorber are determined and the design characteristics of beam shaping assembly, including the materials and thicknesses of reflector and moderator are considered.

  9. Calculation of Coincidence Summing Correction Factors for an HPGe detector using GEANT4.

    PubMed

    Giubrone, G; Ortiz, J; Gallardo, S; Martorell, S; Bas, M C

    2016-07-01

    The aim of this paper was to calculate the True Coincidence Summing Correction Factors (TSCFs) for an HPGe coaxial detector in order to correct the summing effect as a result of the presence of (88)Y and (60)Co in a multigamma source used to obtain a calibration efficiency curve. Results were obtained for three volumetric sources using the Monte Carlo toolkit, GEANT4. The first part of this paper deals with modeling the detector in order to obtain a simulated full energy peak efficiency curve. A quantitative comparison between the measured and simulated values was made across the entire energy range under study. The True Summing Correction Factors were calculated for (88)Y and (60)Co using the full peak efficiencies obtained with GEANT4. This methodology was subsequently applied to (134)Cs, and presented a complex decay scheme. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Radial dose distributions from protons of therapeutic energies calculated with Geant4-DNA.

    PubMed

    Wang, He; Vassiliev, Oleg N

    2014-07-21

    Models based on the amorphous track structure approximation have been successful in predicting the biological effects of heavy charged particles. Development of such models remains an active area of research that includes applications to hadrontherapy. In such models, the radial distribution of the dose deposited by delta electrons and directly by the particle is the main characteristic of track structure. We calculated these distributions with Geant4-DNA Monte Carlo code for protons in the energy range from 10 to 100 MeV. These results were approximated by a simple formula that combines the well-known inverse square distance dependence with two factors that eliminate the divergence of the radial dose integral at both small and large distances. A clear physical interpretation is given to the asymptotic behaviour of the radial dose distribution resulting from these two factors. The proposed formula agrees with the Monte Carlo data within 10% for radial distances of up to 10 μm, which corresponds to a dose range covering over eight orders of magnitude. Differences between our results and those of previously published analytical models are discussed.

  11. Radial dose distributions from protons of therapeutic energies calculated with Geant4-DNA

    NASA Astrophysics Data System (ADS)

    Wang, He; Vassiliev, Oleg N.

    2014-07-01

    Models based on the amorphous track structure approximation have been successful in predicting the biological effects of heavy charged particles. Development of such models remains an active area of research that includes applications to hadrontherapy. In such models, the radial distribution of the dose deposited by delta electrons and directly by the particle is the main characteristic of track structure. We calculated these distributions with Geant4-DNA Monte Carlo code for protons in the energy range from 10 to 100 MeV. These results were approximated by a simple formula that combines the well-known inverse square distance dependence with two factors that eliminate the divergence of the radial dose integral at both small and large distances. A clear physical interpretation is given to the asymptotic behaviour of the radial dose distribution resulting from these two factors. The proposed formula agrees with the Monte Carlo data within 10% for radial distances of up to 10 μm, which corresponds to a dose range covering over eight orders of magnitude. Differences between our results and those of previously published analytical models are discussed.

  12. The GEANT4 toolkit for microdosimetry calculations: application to microbeam radiation therapy (MRT).

    PubMed

    Spiga, J; Siegbahn, E A; Bräuer-Krisch, E; Randaccio, P; Bravin, A

    2007-11-01

    Theoretical dose distributions for microbeam radiation therapy (MRT) are computed in this paper using the GEANT4 Monte Carlo (MC) simulation toolkit. MRT is an innovative experimental radiotherapy technique carried out using an array of parallel microbeams of synchrotron-wiggler-generated x rays. Although the biological mechanisms underlying the effects of microbeams are still largely unknown, the effectiveness of MRT can be traced back to the natural ability of normal tissues to rapidly repair small damages to the vasculature, and on the lack of a similar healing process in tumoral tissues. Contrary to conventional therapy, in which each beam is at least several millimeters wide, the narrowness of the microbeams allows a rapid regeneration of the blood vessels along the beams' trajectories. For this reason the calculation of the "valley" dose is of crucial importance and the correct use of MC codes for such purposes must be understood. GEANT4 offers, in addition to the standard libraries, a specialized package specifically designed to deal with electromagnetic interactions of particles with matter for energies down to 250 eV. This package implements two different approaches for electron and photon transport, one based on evaluated data libraries, the other adopting analytical models. These features are exploited to cross-check theoretical computations for MRT. The lateral and depth dose profiles are studied for the irradiation of a 20 cm diameter, 20 cm long cylindrical phantom, with cylindrical sources of different size and energy. Microbeam arrays are simulated with the aid of superposition algorithms, and the ratios of peak-to-valley doses are computed for typical cases used in preclinical assays. Dose profiles obtained using the GEANT4 evaluated data libraries and analytical models are compared with simulation results previously obtained using the PENELOPE code. The results show that dose profiles computed with GEANT4's analytical model are almost

  13. Comparison of GEANT4 Simulations with Experimental Data for Thick Al Absorbers

    SciTech Connect

    Yevseyeva, Olga; Assis, Joaquim de; Diaz, Katherin; Lopes, Ricardo

    2009-06-03

    Proton beams in medical applications deal with relatively thick targets like the human head or trunk. Therefore, relatively small differences in the total proton stopping power given, for example, by the different models provided by GEANT4 can lead to significant disagreements in the final proton energy spectra when integrated along lengthy proton trajectories. This work presents proton energy spectra obtained by GEANT4.8.2 simulations using ICRU49, Ziegler1985 and Ziegler2000 models for 19.68 MeV protons passing through a number of Al absorbers with various thicknesses. The spectra were compared with the experimental data, with TRIM/SRIM2008 and MCNPX2.4.0 simulations, and with the Payne analytical solution for the transport equation in the Fokker-Plank approximation. It is shown that the MCNPX simulations reasonably reproduce well all experimental spectra. For the relatively thin targets all the methods give practically identical results but this is not the same for the thick absorbers. It should be noted that all the spectra were measured at the proton energies significantly above 2 MeV, i.e., in the so-called 'Bethe-Bloch region'. Therefore the observed disagreements in GEANT4 results, simulated with different models, are somewhat unexpected. Further studies are necessary for better understanding and definitive conclusions.

  14. Geant4 simulations of STIX Caliste-SO detector's response to solar X-ray radiation

    NASA Astrophysics Data System (ADS)

    Barylak, Jaromir; Barylak, Aleksandra; Mrozek, Tomasz; Steślicki, Marek; Podgórski, Piotr; Netzel, Henryka

    Spectrometer/Telescope for Imaging X-rays (STIX) is a part of Solar Orbiter (SO) science payload. SO will be launched in October 2018, and after three years of cruise phase, it will reach orbit with perihelion distance of 0.3 a.u. STIX is a Fourier imager equipped with pairs of grids that comprise the flare hard X-ray tomograph. Similar imager types were already used in the past (eq. RHESSI, Yohkoh/HXT), but STIX will incorporate Moiré modulation and a new type of pixelized detectors with CdTe sensor. We developed a method of modeling these detectors' response matrix (DRM) using the Geant4 simulations of X-ray photons interactions with CdTe crystals. Taking into account known detector effects (Fano noise, hole tailing etc.) we modeled the resulting spectra with high accuracy. Comparison of Caliste-SO laboratory measurements of 241Am decay spectrum with our results shows a very good agreement. The modeling based on the Geant4 simulations significantly improves our understanding of detector response to X-ray photons. Developed methodology gives opportunity for detailed simulation of whole instrument response with complicated geometry and secondary radiation from cosmic ray particles taken into account. Moreover, we are developing the Geant4 simulations of aging effects which decrease detector's performance.

  15. Adaptation of GEANT4 to Monte Carlo dose calculations based on CT data.

    PubMed

    Jiang, H; Paganetti, H

    2004-10-01

    The GEANT4 Monte Carlo code provides many powerful functions for conducting particle transport simulations with great reliability and flexibility. However, as a general purpose Monte Carlo code, not all the functions were specifically designed and fully optimized for applications in radiation therapy. One of the primary issues is the computational efficiency, which is especially critical when patient CT data have to be imported into the simulation model. In this paper we summarize the relevant aspects of the GEANT4 tracking and geometry algorithms and introduce our work on using the code to conduct dose calculations based on CT data. The emphasis is focused on modifications of the GEANT4 source code to meet the requirements for fast dose calculations. The major features include a quick voxel search algorithm, fast volume optimization, and the dynamic assignment of material density. These features are ready to be used for tracking the primary types of particles employed in radiation therapy such as photons, electrons, and heavy charged particles. Recalculation of a proton therapy treatment plan generated by a commercial treatment planning program for a paranasal sinus case is presented as an example.

  16. Introducing Third-Year Undergraduates to GEANT4 Simulations of Light Transport and Collection in Scintillation Materials

    ERIC Educational Resources Information Center

    Riggi, Simone; La Rocca, Paola; Riggi, Francesco

    2011-01-01

    GEANT4 simulations of the processes affecting the transport and collection of optical photons generated inside a scintillation detector were carried out, with the aim to complement the educational material offered by textbooks to third-year physics undergraduates. Two typical situations were considered: a long scintillator strip with and without a…

  17. Introducing Third-Year Undergraduates to GEANT4 Simulations of Light Transport and Collection in Scintillation Materials

    ERIC Educational Resources Information Center

    Riggi, Simone; La Rocca, Paola; Riggi, Francesco

    2011-01-01

    GEANT4 simulations of the processes affecting the transport and collection of optical photons generated inside a scintillation detector were carried out, with the aim to complement the educational material offered by textbooks to third-year physics undergraduates. Two typical situations were considered: a long scintillator strip with and without a…

  18. GEANT4 simulations of Cherenkov reaction history diagnostics

    SciTech Connect

    Rubery, M. S.; Horsfield, C. J.; Herrmann, H. W.; Kim, Y.; Mack, J. M.; Young, C. S.; Caldwell, S. E.; Evans, S. C.; Sedilleo, T. J.; McEvoy, A.; Miller, E. K.; Stoeffl, W.; Ali, Z.

    2010-10-15

    This paper compares the results from a GEANT4 simulation of the gas Cherenkov detector 1 (GCD1) with previous simulations and experimental data from the Omega laser facility. The GCD1 collects gammas emitted during a deuterium-tritium capsule implosion and converts them, through several processes, to Cherenkov light. Photon signals are recorded using subnanosecond photomultiplier tubes, producing burn reaction histories. The GEANT4 GCD1 simulation is first benchmarked against ACCEPT, an integrated tiger series code, with good agreement. The simulation is subsequently compared with data from the Omega laser facility, where experiments have been performed to measure the effects of Hohlraum materials on reaction history signals, in preparation for experiments at the National Ignition Facility.

  19. Comparison of hadron shower data in the PAMELA experiment with Geant 4 simulations

    NASA Astrophysics Data System (ADS)

    Alekseev, V. V.; Dunaeva, O. A.; Bogomolov, Yu V.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Rodenko, S. A.

    2017-01-01

    The sampling imaging electromagnetic calorimeter of ≈ 16.3 radiation lengths and ≈ 0.6 nuclear interaction length designed and constructed by the PAMELA collaboration as a part of the large magnetic spectrometer PAMELA. Calorimeter consists of 44 single-sided silicon sensor planes interleaved with 22 plates of tungsten absorber (thickness of each tungsten layer 0.26 cm). Silicon planes are composed of a 3 × 3 matrix of silicon detectors, each segmented into 32 read-out strips with a pitch of 2.4 mm. The orientation of the strips of two consecutive layers is orthogonal and therefore provides two-dimensional spatial information. Due to the high granularity, the development of hadronic showers can be study with a good precision. In this work a Monte Carlo simulations (based on Geant4) performed using different available models, and including detector and physical effects, compared with the experimental data obtained on the near Earth orbit. Response of the PAMELA calorimeter to hadronic showers investigated including total energy release in calorimeter and transverse shower profile characteristics.

  20. Monte Carlo simulation of the ELIMED beamline using Geant4

    NASA Astrophysics Data System (ADS)

    Pipek, J.; Romano, F.; Milluzzo, G.; Cirrone, G. A. P.; Cuttone, G.; Amico, A. G.; Margarone, D.; Larosa, G.; Leanza, R.; Petringa, G.; Schillaci, F.; Scuderi, V.

    2017-03-01

    In this paper, we present a Geant4-based Monte Carlo application for ELIMED beamline [1-6] simulation, including its features and several preliminary results. We have developed the application to aid the design of the beamline, to estimate various beam characteristics, and to assess the amount of secondary radiation. In future, an enhanced version of this application will support the beamline users when preparing their experiments.

  1. Implementation of the n-body Monte-Carlo event generator into the Geant4 toolkit for photonuclear studies

    NASA Astrophysics Data System (ADS)

    Luo, Wen; Lan, Hao-yang; Xu, Yi; Balabanski, Dimiter L.

    2017-03-01

    A data-based Monte Carlo simulation algorithm, Geant4-GENBOD, was developed by coupling the n-body Monte-Carlo event generator to the Geant4 toolkit, aiming at accurate simulations of specific photonuclear reactions for diverse photonuclear physics studies. Good comparisons of Geant4-GENBOD calculations with reported measurements of photo-neutron production cross-sections and yields, and with reported energy spectra of the 6Li(n,α)t reaction were performed. Good agreements between the calculations and experimental data were found and the validation of the developed program was verified consequently. Furthermore, simulations for the 92Mo(γ,p) reaction of astrophysics relevance and photo-neutron production of 99Mo/99mTc and 225Ra/225Ac radioisotopes were investigated, which demonstrate the applicability of this program. We conclude that the Geant4-GENBOD is a reliable tool for study of the emerging experiment programs at high-intensity γ-beam laboratories, such as the Extreme Light Infrastructure - Nuclear Physics facility and the High Intensity Gamma-Ray Source at Duke University.

  2. Geant4 simulations on Compton scattering of laser photons on relativistic electrons

    SciTech Connect

    Filipescu, D.; Utsunomiya, H.; Gheorghe, I.; Glodariu, T.; Tesileanu, O.; Shima, T.; Takahisa, K.; Miyamoto, S.

    2015-02-24

    Using Geant4, a complex simulation code of the interaction between laser photons and relativistic electrons was developed. We implemented physically constrained electron beam emittance and spacial distribution parameters and we also considered a Gaussian laser beam. The code was tested against experimental data produced at the γ-ray beam line GACKO (Gamma Collaboration Hutch of Konan University) of the synchrotron radiation facility NewSUBARU. Here we will discuss the implications of transverse missallignments of the collimation system relative to the electron beam axis.

  3. Calibration of the radiation monitor onboard Akebono using Geant4

    NASA Astrophysics Data System (ADS)

    Asai, Keiko; Takashima, Takeshi; Koi, Tatsumi; Nagai, Tsugunobu

    Natural high-energy electrons and protons (keV-MeV) in the space contaminate the data re-ciprocally. In order to calibrate the energy ranges and to remove data contamination on the radiation monitor (RDM) onboard the Japanese satellite, Akebono (EXOS-D), the detector is investigated using the Geant4 simulation toolkit of computational particle tracing. The semi-polar orbiting Akebono, launched in February 1989, is active now. This satellite has been observed the space environment at altitudes of several thousands km. The RDM instrument onboard Akebono monitors energetic particles in the Earth's radiation belt and gives important data accumulated for about two solar cycles. The data from RDM are for electrons in three energy channels of 0.3 MeV, protons in three energy channels of ¿ 30 MeV, and alpha particles in one energy channels of 15-45 MeV. The energy ranges are however based on information of about 20 years ago so that the data seem to include some errors actuary. In addition, these data include contamination of electrons and protons reciprocally. Actuary it is noticed that the electron data are contaminated by the solar protons but unknown quantitative amount of the contamination. Therefore we need data calibration in order to correct the energy ranges and to remove data contamination. The Geant4 simulation gives information of trajectories of incident and secondary particles whose are interacted with materials. We examine the RDM monitor using the Geant4 simulation. We find from the results that relativistic electrons of MeV behave quite complicatedly because of particle-material interaction in the instrument. The results indicate that efficiencies of detection and contamination are dependent on energy. This study compares the electron data from Akebono RDM with the simultaneous observation of CRRES and tries to lead the values of correction for each of the energy channels.

  4. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    SciTech Connect

    Shtejer, K.; Arruda-Neto, J. D. T.; Rodrigues, T. E.; Schulte, R.; Wroe, A.; Menezes, M. O. de; Moralles, M.

    2008-08-11

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, {alpha}{sup 3}He to the total dose compared to the GEANT4 physical models chosen in this work.

  5. Comparison of MCNPX and GEANT4 to Predict the Contribution of Non-elastic Nuclear Interactions to Absorbed Dose in Water, PMMA and A150

    NASA Astrophysics Data System (ADS)

    Shtejer, K.; Arruda-Neto, J. D. T.; Schulte, R.; Wroe, A.; Rodrigues, T. E.; de Menezes, M. O.; Moralles, M.; Guzmán, F.; Manso, M. V.

    2008-08-01

    Proton induced non-elastic nuclear reactions play an important role in the dose distribution of clinically used proton beams as they deposit dose of high biological effectiveness both within the primary beam path as well as outside the beam to untargeted tissues. Non-elastic nuclear reactions can be evaluated using transport codes based on the Monte Carlo method. In this work, we have utilized the Los Alamos code MCNPX and the CERN GEANT4 toolkit, which are currently the most widely used Monte Carlo programs for proton radiation transport simulations in medical physics, to study the contribution of non-elastic nuclear interactions to the absorbed dose of proton beams in the therapeutic energy range. The impact of different available theoretical models to address the nuclear reaction process was investigated. The contribution of secondary particles from non-elastic nuclear reactions was calculated in three materials relevant in radiotherapy applications: water, PMMA and A150. The results evidence that there are differences in the calculated contribution of the secondary particles heavier than protons to the absorbed dose, with different approaches to model the nuclear reactions. The MCNPX calculation give rise to a larger contribution of d, t, α3He to the total dose compared to the GEANT4 physical models chosen in this work.

  6. Software Aspects of the Geant4 Validation Repository

    SciTech Connect

    Dotti, Andrea; Wenzel, Hans; Elvira, Daniel; Genser, Krzysztof; Yarba, Julia; Carminati, Federico; Folger, Gunter; Konstantinov, Dmitri; Pokorski, Witold; Ribon, Alberto

    2016-01-01

    The Geant4, GeantV and GENIE collaborations regularly perform validation and regression tests for simulation results. DoSSiER (Database of Scientic Simulation and Experimental Results) is being developed as a central repository to store the simulation results as well as the experimental data used for validation. DoSSiER is easily accessible via a web application. In addition, a web service allows for programmatic access to the repository to extract records in JSON or XML exchange formats. In this article, we describe the functionality and the current status of various components of DoSSiER as well as the technology choices we made.

  7. SOLPEX x-ray polarimeter detector luminescence background calculated using Geant4 simulation software

    NASA Astrophysics Data System (ADS)

    Gorgolewski, Aleksander; Barylak, Jaromir; Steślicki, Marek; Szaforz, Å.»aneta; BÄ kała, Jarosław

    2016-09-01

    The Soft X-ray Solar polarimeter-spectrometer (SOLPEX) experiment is planned to be placed in Roscosmos' Multipurpose Laboratory Module "NAUKA" on International Space Station (ISS) in 2019. The experiment is design to detect polarization and X-ray spectra of solar flares. Due to very high, few percent, linear polarization detection limit, accurate background estimation and modeling is crucial. Calculating the background photoelectric effect, Compton scattering and Bremsstrahlung were taken into account. Luminescence background from particles produced in solar flares was simulated using Geant4. Additionally, theoretical spectra was modeled in order to simulate full SOLPEX detector response for M5 and X1 solar flare classes.

  8. Microdosimetry of alpha particles for simple and 3D voxelised geometries using MCNPX and Geant4 Monte Carlo codes.

    PubMed

    Elbast, M; Saudo, A; Franck, D; Petitot, F; Desbrée, A

    2012-07-01

    Microdosimetry using Monte Carlo simulation is a suitable technique to describe the stochastic nature of energy deposition by alpha particle at cellular level. Because of its short range, the energy imparted by this particle to the targets is highly non-uniform. Thus, to achieve accurate dosimetric results, the modelling of the geometry should be as realistic as possible. The objectives of the present study were to validate the use of the MCNPX and Geant4 Monte Carlo codes for microdosimetric studies using simple and three-dimensional voxelised geometry and to study their limit of validity in this last case. To that aim, the specific energy (z) deposited in the cell nucleus, the single-hit density of specific energy f(1)(z) and the mean-specific energy were calculated. Results show a good agreement when compared with the literature using simple geometry. The maximum percentage difference found is <6 %. For voxelised phantom, the study of the voxel size highlighted that the shape of the curve f(1)(z) obtained with MCNPX for <1 µm voxel size presents a significant difference with the shape of non-voxelised geometry. When using Geant4, little differences are observed whatever the voxel size is. Below 1 µm, the use of Geant4 is required. However, the calculation time is 10 times higher with Geant4 than MCNPX code in the same conditions.

  9. Influence of thyroid volume reduction on absorbed dose in 131I therapy studied by using Geant4 Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Ziaur, Rahman; Sikander, M. Mirza; Waheed, Arshed; Nasir, M. Mirza; Waheed, Ahmed

    2014-05-01

    A simulation study has been performed to quantify the effect of volume reduction on the thyroid absorbed dose per decay and to investigate the variation of energy deposition per decay due to β- and γ-activity of 131I with volume/mass of thyroid, for water, ICRP- and ICRU-soft tissue taken as thyroid material. A Monte Carlo model of the thyroid, in the Geant4 radiation transport simulation toolkit was constructed to compute the β- and γ-absorbed dose in the simulated thyroid phantom for various values of its volume. The effect of the size and shape of the thyroid on energy deposition per decay has also been studied by using spherical, ellipsoidal and cylindrical models for the thyroid and varying its volume in 1-25 cm3 range. The relative differences of Geant4 results for different models with each other and MCNP results lie well below 1.870%. The maximum relative difference among the Geant4 estimated results for water with ICRP and ICRU soft tissues is not more than 0.225%. S-values for ellipsoidal, spherical and cylindrical thyroid models were estimated and the relative difference with published results lies within 3.095%. The absorbed fraction values for beta particles show a good agreement with published values within 2.105% deviation. The Geant4 based simulation results of absorbed fractions for gammas again show a good agreement with the corresponding MCNP and EGS4 results (±6.667%) but have 29.032% higher values than that of MIRD calculated values. Consistent with previous studies, the reduction of the thyroid volume is found to have a substantial effect on the absorbed dose. Geant4 simulations confirm dose dependence on the volume/mass of thyroid in agreement with MCNP and EGS4 computed values but are substantially different from MIRD8 data. Therefore, inclusion of size/mass dependence is indicated for 131I radiotherapy of the thyroid.

  10. Commissioning of 6 MV medical linac for dynamic MLC-based IMRT on Monte Carlo code GEANT4.

    PubMed

    Okamoto, Hiroyuki; Fujita, Yukio; Sakama, Kyoko; Saitoh, Hidetoshi; Kanai, Tatsuaki; Itami, Jun; Kohno, Toshiyuki

    2014-07-01

    Monte Carlo simulation is the most accurate tool for calculating dose distributions. In particular, the Electron Gamma shower computer code has been widely used for multi-purpose research in radiotherapy, but Monte Carlo GEANT4 (GEometry ANd Tracking) is rare for radiotherapy with photon beams and needs to be verified further under various irradiation conditions, particularly multi-leaf collimator-based intensity-modulated radiation therapy (MLC-based IMRT). In this study, GEANT4 was used for modeling of a 6 MV linac for dynamic MLC-based IMRT. To verify the modeling of our linac, we compared the calculated data with the measured depth-dose for a 10 × 10 cm(2) field and the measured dose profile for a 35 × 35 cm(2) field. Moreover, 120 MLCs were modeled on the GEANT4. Five tests of MLC modeling were performed: (I) MLC transmission, (II) MLC transmission profile including intra- and inter-leaf leakage, (III) tongue-and-groove leakage, (IV) a simple field with different field sizes by use of MLC and (V) a dynamic MLC-based IMRT field. For all tests, the calculations were compared with measurements of an ionization chamber and radiographic film. The calculations agreed with the measurements: MLC transmissions by calculations and measurements were 1.76 ± 0.01 and 1.87 ± 0.01 %, respectively. In gamma evaluation method (3 %/3 mm), the pass rates of the (IV) and (V) tests were 98.5 and 97.0 %, respectively. Furthermore, tongue-and-groove leakage could be calculated by GEANT4, and it agreed with the film measurements. The procedure of commissioning of dynamic MLC-based IMRT for GEANT4 is proposed in this study.

  11. BC404 scintillators as gamma locators studied via Geant4 simulations

    NASA Astrophysics Data System (ADS)

    Cortés, M. L.; Hoischen, R.; Eisenhauer, K.; Gerl, J.; Pietralla, N.

    2014-05-01

    In many applications in industry and academia, an accurate determination of the direction from where gamma rays are emitted is either needed or desirable. Ion-beam therapy treatments, the search for orphan sources, and homeland security applications are examples of fields that can benefit from directional sensitivity to gamma-radiation. Scintillation detectors are a good option for these types of applications as they have relatively low cost, are easy to handle and can be produced in a large range of different sizes. In this work a Geant4 simulation was developed to study the directional sensitivity of different BC404 scintillator geometries and arrangements. The simulation includes all the physical processes relevant for gamma detection in a scintillator. In particular, the creation and propagation of optical photons inside the scintillator was included. A simplified photomultiplier tube model was also simulated. The physical principle exploited is the angular dependence of the shape of the energy spectrum obtained from thin scintillator layers when irradiated from different angles. After an experimental confirmation of the working principle of the device and a check of the simulation, the possibilities and limitations of directional sensitivity to gamma radiation using scintillator layers was tested. For this purpose, point-like sources of typical energies expected in ion-beam therapy were used. Optimal scintillator thicknesses for different energies were determined and the setup efficiencies calculated. The use of arrays of scintillators to reconstruct the direction of incoming gamma rays was also studied. For this case, a spherical source emitting Bremsstrahlung radiation was used together with a setup consisting of scintillator layers. The capability of this setup to identify the center of the extended source was studied together with its angular resolution.

  12. Geant4-Simulations for cellular dosimetry in nuclear medicine.

    PubMed

    Freudenberg, Robert; Wendisch, Maria; Kotzerke, Jörg

    2011-12-01

    The application of unsealed radionuclides in radiobiological experiments can lead to intracellular radionuclide uptake and an increased absorbed dose. Accurate dose quantification is essential to assess observed radiobiological effects. Due to small cellular dimensions direct dose measurement is impossible. We will demonstrate the application of Monte Carlo simulations for dose calculation. Dose calculations were performed using the Geant4 Monte Carlo toolkit, wherefore typical experimental situations were designed. Dose distributions inside wells were simulated for different radionuclides. S values were simulated for spherical cells and cell monolayers of different diameter. Concomitantly experiments were performed using the PC Cl3 cell line with mediated radionuclide uptake. For various activity distributions cellular survival was measured. We yielded S values for dose distribution inside the wells. Calculated S values for a single cell are in good agreement to S values provided in the literature (ratio 0.87 to 1.07). Cross-dose is up to ten times higher for Y-90. Concomitantly performed cellular experiments confirm the dose calculation. Furthermore the necessity of correct dose calculation was shown for assessment of radiobiological effects after application of unsealed radionuclides. Thereby the feasibility of using Geant4 was demonstrated.

  13. BoGEMMS: the Bologna Geant4 multi-mission simulator

    NASA Astrophysics Data System (ADS)

    Bulgarelli, A.; Fioretti, V.; Malaguti, P.; Trifoglio, M.; Gianotti, F.

    2012-07-01

    BoGEMMS, (Bologna Geant4 Multi-Mission Simulator) is a software project for fast simulation of payload on board of scientific satellites for prompt background evaluation that has been developed at the INAF/IASF Bologna. By exploiting the Geant4 set of libraries, BoGEMMS allows to interactively set the geometrical and physical parameters (e.g. physics list, materials and thicknesses), recording the interactions (e.g. energy deposit, position, interacting particle) in NASA FITS and CERN root format output files and filtering the output as a real observation in space, to finally produce the background detected count rate and spectra. Four different types of output can be produced by the BoGEMMS capturing different aspects of the interactions. The simulator can also run in parallel jobs and store the results in a centralized server via xrootd protocol. The BoGEMMS is a multi-mission tool, generally designed to be applied to any high-energy mission for which the shielding and instruments performances analysis is required.

  14. Assessment of a new multileaf collimator concept using GEANT4 Monte Carlo simulations.

    PubMed

    Tacke, Martin B; Szymanowski, Hanitra; Oelfke, Uwe; Schulze, Carsten; Nuss, Susanne; Wehrwein, Eugen; Leidenberger, Stefan

    2006-04-01

    The aim of the work was to investigate in advance the dosimetric properties of a new multileaf collimator (MLC) concept with the help of Monte Carlo (MC) simulations prior to the production of a prototype. The geometrical design of the MLC was implemented in the MC code GEANT4. For the simulation of a 6 MV treatment beam, an experimentally validated phase space and a virtual spatial Gaussian-shaped model placed in the origin were used. For the simulation of the geometry in GEANT4, the jaws and the two leaf packages were implemented with the help of computer-aided design data. First, transmission values for different tungsten alloys were extracted using the simulation codes GEANT4 and BEAMnrc and compared to experimental measurements. In a second step, high-resolution simulations were performed to detect the leakage at depth of maximum dose. The 20%-80% penumbra along the travel direction of the leaves was determined using 10 x 10 cm2 fields shifted along the x- and y-axis. The simulated results were compared with measured data. The simulation of the transmission values for different tungsten alloys showed a good agreement with the experimental measurements (within 2.0%). This enabled an accurate estimation of the attenuation coefficient for the various leaf materials. Simulations with varying width of the spatial Gaussian distribution showed that the leakage and the penumbra depend very much on this parameter: for instance, for widths of 2 and 4 mm, the interleaf leakage is below 0.3% and 0.75%, respectively. The results for the leakage and the penumbra (4.7+/-0.5 mm) are in good agreement with the measurements. This study showed that GEANT4 is appropriate for the investigation of the dosimetric properties of a multileaf collimator. In particular, a quantification of the leakage, the penumbra, and the tongue-and-groove effect and an evaluation of the influence of the beam parameters such as the width of the Gaussian distribution was possible.

  15. Geant4-based simulations of charge collection in CMOS Active Pixel Sensors

    NASA Astrophysics Data System (ADS)

    Esposito, M.; Price, T.; Anaxagoras, T.; Allinson, N. M.

    2017-03-01

    Geant4 is an object-oriented toolkit for the simulation of the interaction of particles and radiation with matter. It provides a snapshot of the state of a simulated particle in time, as it travels through a specified geometry. One important area of application is the modelling of radiation detector systems. Here, we extend the abilities of such modelling to include charge transport and sharing in pixelated CMOS Active Pixel Sensors (APSs); though similar effects occur in other pixel detectors. The CMOS APSs discussed were developed in the framework of the PRaVDA consortium to assist the design of custom sensors to be used in an energy-range detector for proton Computed Tomography (pCT). The development of ad-hoc classes, providing a charge transport model for a CMOS APS and its integration into the standard Geant4 toolkit, is described. The proposed charge transport model includes, charge generation, diffusion, collection, and sharing across adjacent pixels, as well as the full electronic chain for a CMOS APS. The proposed model is validated against experimental data acquired with protons in an energy range relevant for pCT.

  16. Comparisons of hadrontherapy-relevant data to nuclear interaction codes in the Geant4 toolkit

    NASA Astrophysics Data System (ADS)

    Braunn, B.; Boudard, A.; Colin, J.; Cugnon, J.; Cussol, D.; David, J. C.; Kaitaniemi, P.; Labalme, M.; Leray, S.; Mancusi, D.

    2013-03-01

    Comparisons between experimental data, INCL and other nuclear models available in the Geant4 toolkit are presented. The data used for the comparisons come from a fragmentation experiment realised at GANIL facility. The main purpose of this experiment was to measure production rates and angular distributions of emitted particles from the collision of a 95.A MeV 12C beam and thick PMMA (plastic) targets. The latest version of the Intra Nuclear Cascade of Liege code extended to nucleus-nucleus collisions for ion beam therapy application will be described. This code as well as JQMD and the Geant4 binary cascade has been compared with these hadrontherapy-oriented experimental data. The results from the comparisons exhibit an overall qualitative agreement between the models and the experimental data. However, at a quantitative level, it has been shown that none of this three models manage to reproduce precisely all the data. The nucleus-nucleus extension of INCL, which is not predictive enough for ion beam therapy application yet, has nevertheless proven to be competitive with other nuclear collisions codes.

  17. Simulation of a Helical Channel using GEANT4

    SciTech Connect

    Elvira, V. D.; Lebrun, P.; Spentzouris, P.

    2001-02-01

    We present a simulation of a 72 m long cooling channel proposed by V. Balbekov based on the helical cooling concept developed by Ya. Derbenev. LiH wedge absorbers provide the energy loss mechanism and 201 MHz cavities are used for re-acceleration. They are placed inside a main solenoidal field to focus the beam. A helical field with an amplitude of 0.3 T and a period of 1.8 m provides momentum dispersion for emittance exchange.The simulation is performed using GEANT4. The total fractional transmission is 0.85, and the transverse, longitudinal, and 3-D cooling factors are 3.75, 2.27, and 14.61, respectively. Some version of this helical channel could eventually be used to replace the first section of the double flip channel to keep the longitudinal emittance under control and increase transmission. Although this is an interesting option, the technical challenges are still significant.

  18. Nuclear spectroscopy with Geant4: Proton and neutron emission & radioactivity

    SciTech Connect

    Sarmiento, L. G. Rudolph, D.

    2016-07-07

    With the aid of a novel combination of existing equipment – JYFLTRAP and the TASISpec decay station – it is possible to perform very clean quantum-state selective, high-resolution particle-γ decay spectroscopy. We intend to study the determination of the branching ratio of the ℓ = 9 proton emission from the I{sup π} = 19/2{sup −}, 3174-keV isomer in the N = Z − 1 nucleus {sup 53}Co. The study aims to initiate a series of similar experiments along the proton dripline, thereby providing unique insights into “open quantum systems”. The technique has been pioneered in case studies using SHIPTRAP and TASISpec at GSI. Newly available radioactive decay modes in Geant4 simulations are going to corroborate the anticipated experimental results.

  19. Thermal neutron response of a boron-coated GEM detector via GEANT4 Monte Carlo code.

    PubMed

    Jamil, M; Rhee, J T; Kim, H G; Ahmad, Farzana; Jeon, Y J

    2014-10-22

    In this work, we report the design configuration and the performance of the hybrid Gas Electron Multiplier (GEM) detector. In order to make the detector sensitive to thermal neutrons, the forward electrode of the GEM has been coated with the enriched boron-10 material, which works as a neutron converter. A total of 5×5cm(2) configuration of GEM has been used for thermal neutron studies. The response of the detector has been estimated via using GEANT4 MC code with two different physics lists. Using the QGSP_BIC_HP physics list, the neutron detection efficiency was determined to be about 3%, while with QGSP_BERT_HP physics list the efficiency was around 2.5%, at the incident thermal neutron energies of 25meV. The higher response of the detector proves that GEM-coated with boron converter improves the efficiency for thermal neutrons detection. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Distributed geant4 simulation in medical and space science applications using DIANE framework and the GRID

    NASA Astrophysics Data System (ADS)

    Mościcki, Jakub T.; Guatelli, Susanna; Mantero, Alfonso; Pia, M. G.

    2003-09-01

    Distributed computing is one of the most important trends in IT which has recently gained significance for large-scale scientific applications. Distributed Analysis Environment (DIANE) [1] is a R&D study, focusing on semi-interactive parallel and remote data analysis and simulation, which has been conducted at CERN. DIANE provides necessary software infrastructure for parallel scientific applications in the master-worker model. Advanced error recovery policies, automatic book-keeping of distributed jobs and on-line monitoring and control tools are provided. DIANE makes a transparent use of a number of different middleware implementations such as load balancing service (LSF, PBS, GRID Resource Broker, Condor) and security service (GSI, Kerberos, openssh). A number of distributed Geant 4 simulations have been deployed and tested, ranging from interactive radiotherapy treatment planning using dedicated clusters in hospitals, to globally-distributed simulations of astrophysics experiments using the European Data Grid middleware. This paper describes the general concepts behind the DIANE framework and results of the first tests with distributed Geant 4 simulations.

  1. Development and validation of a GEANT4 radiation transport code for CT dosimetry

    PubMed Central

    Carver, DE; Kost, SD; Fernald, MJ; Lewis, KG; Fraser, ND; Pickens, DR; Price, RR; Stabin, MG

    2014-01-01

    We have created a radiation transport code using the GEANT4 Monte Carlo toolkit to simulate pediatric patients undergoing CT examinations. The focus of this paper is to validate our simulation with real-world physical dosimetry measurements using two independent techniques. Exposure measurements were made with a standard 100-mm CT pencil ionization chamber, and absorbed doses were also measured using optically stimulated luminescent (OSL) dosimeters. Measurements were made in air, a standard 16-cm acrylic head phantom, and a standard 32-cm acrylic body phantom. Physical dose measurements determined from the ionization chamber in air for 100 and 120 kVp beam energies were used to derive photon-fluence calibration factors. Both ion chamber and OSL measurement results provide useful comparisons in the validation of our Monte Carlo simulations. We found that simulated and measured CTDI values were within an overall average of 6% of each other. PMID:25706135

  2. Inter-comparison of Dose Distributions Calculated by FLUKA, GEANT4, MCNP, and PHITS for Proton Therapy

    NASA Astrophysics Data System (ADS)

    Yang, Zi-Yi; Tsai, Pi-En; Lee, Shao-Chun; Liu, Yen-Chiang; Chen, Chin-Cheng; Sato, Tatsuhiko; Sheu, Rong-Jiun

    2017-09-01

    The dose distributions from proton pencil beam scanning were calculated by FLUKA, GEANT4, MCNP, and PHITS, in order to investigate their applicability in proton radiotherapy. The first studied case was the integrated depth dose curves (IDDCs), respectively from a 100 and a 226-MeV proton pencil beam impinging a water phantom. The calculated IDDCs agree with each other as long as each code employs 75 eV for the ionization potential of water. The second case considered a similar condition of the first case but with proton energies in a Gaussian distribution. The comparison to the measurement indicates the inter-code differences might not only due to different stopping power but also the nuclear physics models. How the physics parameter setting affect the computation time was also discussed. In the third case, the applicability of each code for pencil beam scanning was confirmed by delivering a uniform volumetric dose distribution based on the treatment plan, and the results showed general agreement between each codes, the treatment plan, and the measurement, except that some deviations were found in the penumbra region. This study has demonstrated that the selected codes are all capable of performing dose calculations for therapeutic scanning proton beams with proper physics settings.

  3. Geant4 simulations of the Gamma Reaction History Diagnostic at the NIF, Omega and HIGS calibration facility

    NASA Astrophysics Data System (ADS)

    Rubery, Michael; Horsfield, Colin; Herrmann, Hans; Kim, Yong Ho; Mack, Joseph; Young, Carlton; Caldwell, Steven; Evans, Scott; Sedillo, Tom; McEvoy, Aaron; Miller, Kirk; Stoeffl, Wolfgang; Ali, Zaheer; Grafil, Elliott

    2010-11-01

    This paper discusses the development of a Geant4 model of the Gamma Reaction History (GRH) diagnostic at NIF and Omega, Inertial Confinement Fusion (ICF) laser facilities. The GRH diagnostic has been developed to measure bang-time and burn-width parameters for ICF implosions at both facilities, further investigations have also shown that measurements, such as ablator aerial density and ion temperature, may also be possible. Absolute gamma calibration experiments have been performed at the High Intensity Gamma Source (HIGS) facility at Duke University to increase confidence in parameters supplied by simulation for the use in calculations at both laser facilities. A comparison between HIGS data, Geant4 and the ITS ACCEPT code will be presented along with other important GRH properties, such as temporal unit response function, peak-timing shift and Cherenkov production profile, all as a function of pressure and incident gamma energy.

  4. Nuclear reaction measurements on tissue-equivalent materials and GEANT4 Monte Carlo simulations for hadrontherapy

    NASA Astrophysics Data System (ADS)

    De Napoli, M.; Romano, F.; D'Urso, D.; Licciardello, T.; Agodi, C.; Candiano, G.; Cappuzzello, F.; Cirrone, G. A. P.; Cuttone, G.; Musumarra, A.; Pandola, L.; Scuderi, V.

    2014-12-01

    When a carbon beam interacts with human tissues, many secondary fragments are produced into the tumor region and the surrounding healthy tissues. Therefore, in hadrontherapy precise dose calculations require Monte Carlo tools equipped with complex nuclear reaction models. To get realistic predictions, however, simulation codes must be validated against experimental results; the wider the dataset is, the more the models are finely tuned. Since no fragmentation data for tissue-equivalent materials at Fermi energies are available in literature, we measured secondary fragments produced by the interaction of a 55.6 MeV u-1 12C beam with thick muscle and cortical bone targets. Three reaction models used by the Geant4 Monte Carlo code, the Binary Light Ions Cascade, the Quantum Molecular Dynamic and the Liege Intranuclear Cascade, have been benchmarked against the collected data. In this work we present the experimental results and we discuss the predictive power of the above mentioned models.

  5. Nuclear reaction measurements on tissue-equivalent materials and GEANT4 Monte Carlo simulations for hadrontherapy.

    PubMed

    De Napoli, M; Romano, F; D'Urso, D; Licciardello, T; Agodi, C; Candiano, G; Cappuzzello, F; Cirrone, G A P; Cuttone, G; Musumarra, A; Pandola, L; Scuderi, V

    2014-12-21

    When a carbon beam interacts with human tissues, many secondary fragments are produced into the tumor region and the surrounding healthy tissues. Therefore, in hadrontherapy precise dose calculations require Monte Carlo tools equipped with complex nuclear reaction models. To get realistic predictions, however, simulation codes must be validated against experimental results; the wider the dataset is, the more the models are finely tuned.Since no fragmentation data for tissue-equivalent materials at Fermi energies are available in literature, we measured secondary fragments produced by the interaction of a 55.6 MeV u(-1) (12)C beam with thick muscle and cortical bone targets. Three reaction models used by the Geant4 Monte Carlo code, the Binary Light Ions Cascade, the Quantum Molecular Dynamic and the Liege Intranuclear Cascade, have been benchmarked against the collected data. In this work we present the experimental results and we discuss the predictive power of the above mentioned models.

  6. Simulating the DESCANT Neutron Detection Array with the Geant4 Toolkit

    NASA Astrophysics Data System (ADS)

    Turko, Joseph; Bildstein, Vinzenz; Rand, Evan; Maclean, Andrew; Garrett, Paul; Griffin Collaboration Collaboration

    2016-09-01

    The DEuterated SCintillator Array for Neutron Tagging (DESCANT) is a newly developed high-efficiency neutron detection array composed of 70 hexagonal deuterated scintillators. Due to the anisotropic nature of elastic (n,d) scattering, the pulse-height spectra of a deuterated scintillator contains a forward-peaked structure that can be used to determine the energy of the incident neutron without using traditional time-of-flight methods. Simulations of the array are crucial in order to interpret the DESCANT pulse heights, determine the efficiencies of the array, and examine its capabilities for conducting various nuclear decay experiments. To achieve this, we plan: (i) a verification of the low-energy hadronic physics packages in Geant4, (ii) a comparison of simulated spectra with data from a simple cylindrical ``test can'' detector geometry, (iii) expanding the simulated light response to a prototype DESCANT detector, and (iv) simulating the entire DESCANT array. NSERC, CFI.

  7. GEANT4 Simulation of Neutron Detector for DAMPE

    NASA Astrophysics Data System (ADS)

    He, M.; Ma, T.; Chang, J.; Zhang, Y.; Huang, Y. Y.; Zang, J. J.; Wu, J.; Dong, T. K.

    2016-01-01

    During recent tens of years dark matter has gradually become a hot topic in astronomical research field, and related theory researches and experiment projects change with each passing day. The Dark Matter Particle Explorer (DAMPE) of our country is proposed under this background. As the probing object involves high energy electrons, appropriate methods must be taken to distinguish them from protons in order to reduce the event probability of other charged particles (e.g. a proton) being mistaken as electrons. The experiments show that, the hadronic shower of high energy proton in BGO electromagnetic calorimeter, which is usually accompanied by the emitting of large number of secondary neutrons, is significantly different from the electromagnetic shower of high energy electron. Through the detection of secondary neutron signal emitting from the bottom of BGO electromagnetic calorimeter and the shower shape of incident particles in BGO electromagnetic calorimeter, we can effectively distinguish whether the incident particles are high energy protons or electrons. This paper introduces the structure and detecting principle of DAMPE neutron detector. We use Monte-Carlo method with GEANT4 software to simulate the signal emitting from protons and electrons at characteristic energy in the neutron detector, and finally summarize the neutron detector's ability to distinguish protons and electrons under different electron acception efficiencies.

  8. GEANT4 simulation of APEX background radiation and shielding

    NASA Astrophysics Data System (ADS)

    Kaluarachchi, Maduka M.; Cates, Gordon D.; Wojtsekhowski, B.

    2015-04-01

    The A' Experiment (APEX), which is approved to run at the Thomas Jefferson National Accelerator Facility (JLab) Hall A, will search for a new vector boson that is hypothesized to be a possible force carrier that couples to dark matter. APEX results should be sensitive to the mass range of 65 MeV to 550 MeV, and high sensitivity will be achieved by means of a high intensity 100 μA beam on a 0.5 g/cm2 Tungsten target resulting in very high luminosity. The experiment should be able to observe the A ' with a coupling constant α ' ~ 1 × 107 times smaller than the electromagnetic coupling constant α. To deal safely with such enormous intensity and luminosity, a full radiation analysis must be used to help with the design of proper radiation shielding. The purpose of this talk is to present preliminary results obtained by simulating radiation background from the APEX experiment using the 3D Monte-Carlo transport code Geant4. Included in the simulation is a detailed Hall A setup: the hall, spectrometers and shield house, beam dump, beam line, septa magnet with its field, as well as the production target. The results were compared to the APEX test run data and used in development of the radiation shielding for sensitive electronics.

  9. GEANT4 Simulation of Neutron Detector for DAMPE

    NASA Astrophysics Data System (ADS)

    Ming, He; Tao, Ma; Jin, Chang; Yan, Zhang; Yong-yi, Huang; Jing-jing, Zang; Jian, Wu; Tie-kuang, Dong

    2016-10-01

    In recent decades, dark matter has gradually become a hot topic in astronomical research, and the related theoretical research and experimental project are updated with each passing day. The Dark Matter Particle Explorer (DAMPE) of our country was proposed under this background. As the detected object involves high-energy electrons, appropriate methods must be taken to distinguish them from protons, in order to reduce the event probability of other charged particles (for example protons) being mistaken as electrons. The experiments show that the hadron shower of high-energy proton in BGO (Bismuth Germanium Oxide) calorimeter, which is usually accompanied with the emitting of a large number of secondary neutrons, is significantly different from the electromagnetic shower of high-energy electron. Through the detection of secondary neutron signals emerging from the bottom of BGO calorimeter, and the shower shape of incident particles in the BGO calorimeter, we can effectively distinguish whether the incident particles are high-energy protons or electrons. This paper introduces the structure and detection principle of the DAMPE neutron detector. We use the Monte-Carlo method and the GEANT4 software to simulate the signals produced by protons and electrons at the characteristic energy in the neutron detector, and finally summarize the neutron detector's ability to distinguish protons and electrons under different electron acceptabilities.

  10. Geant4 simulations of the lead fluoride calorimeter

    NASA Astrophysics Data System (ADS)

    Savchenko, A. A.; Tishchenko, A. A.; Dabagov, S. B.; Anastasi, A.; Venanzoni, G.; Strikhanov, M. N.; Basti, A.; Bedeschi, F.; Bartolini, M.; Cantatore, G.; Cauz, D.; Corradi, G.; Di Sciascio, G.; Di Stefano, R.; Driutti, A.; Escalante, O.; Ferrari, C.; Fioretti, A.; Gabbanini, C.; Gioiosa, A.; Hampai, D.; Iacovacci, M.; Karuza, M.; Liedl, A.; Lusiani, A.; Marignetti, F.; Mastroianni, S.; Moricciani, D.; Pauletta, G.; Piacentino, G. M.; Raha, N.; Santi, L.

    2017-07-01

    In this paper we simulate the charged particle interaction with complex structures, including the emission, with help of Geant4. We take into account Cherenkov radiation, transition radiation, bremsstrahlung, pair production and other accompanying processes. As an application we investigate the full size electromagnetic calorimeter for the muon g-2 experiment at Fermilab. A calorimeter module consists of a Delrin front panel for installation of the laser calibration system, 54 PbF2 Cherenkov crystals wrapped by black Tedlar paper, and silicon photo-multiplier sensors. We report here on results of a simulation of the radiation from positrons striking the calorimeter system. The Cherenkov radiation expansion when a positron moves down through the calorimeter at the arbitrary angle of incidence has been considered. Both spectral and angular distributions of Cherenkov optical photons in different parts of the calorimeter system was evaluated as well as the transition radiation and pre-shower distributions from both the Delrin panel and the Al vacuum chamber of the g-2 storage ring.

  11. A revision of soft proton scattering at grazing incidence and its implementation in the uc(geant)4 toolkit

    NASA Astrophysics Data System (ADS)

    Guzmán, Alejandro; Perinati, Emanuele; Diebold, Sebastian; Tenzer, Chris; Santangelo, Andrea

    2017-08-01

    The scattering of soft protons inside the Wolter-type optics of X-ray observatories has been proven to concentrate these particles onto the focal plane instruments. The funneling of these protons increases the instrumental background and can also contribute to the degrading of the detectors. The instrumental background and degradation of the detector's performance experienced by Chandra and XMM-Newton is significantly larger than what was expected on the basis of previous Monte Carlo simulations. For Chandra the main issue is the degradation of the energy resolution due to lattice displacements in the detectors. For XMM the contribution to the instrumental background is more significant. In between, new laboratory measurements as well as a revision of the theory are needed to correctly assess the impact of the environmental radiation for future missions. In this publication we present a uc(Geant)4 class that will allow future users to select between either theoretical models or measured data to simulate the scattering of soft protons at grazing angles. To develop this method, we revisit the theory of elastic scattering of protons on polished surfaces and implement these approaches into uc(Geant)4. We also implemented recently performed measurements using parts of eROSITA (extended ROentgen Survey with an Imaging Telescope Array) mirror shells as scattering targets as another scattering model to be used within the uc(Geant)4 toolkit.

  12. Validating Geant4 Versions 7.1 and 8.3 Against 6.1 for BaBar

    SciTech Connect

    Banerjee, Swagato; Brown, David N.; Chen, Chunhui; Cote, David; Dubois-Felsmann, Gregory P.; Gaponenko, Igor; Kim, Peter C.; Lockman, William S.; Neal, Homer A.; Simi, Gabriele; Telnov, Alexandre V.; Wright, Dennis H.; /SLAC

    2011-11-08

    Since 2005 and 2006, respectively, Geant4 versions 7.1 and 8.3 have been available, providing: improvements in modeling of multiple scattering; corrections to muon ionization and improved MIP signature; widening of the core of electromagnetic shower shape profiles; newer implementation of elastic scattering for hadronic processes; detailed implementation of Bertini cascade model for kaons and lambdas, and updated hadronic cross-sections from calorimeter beam tests. The effects of these changes in simulation are studied in terms of closer agreement of simulation using Geant4 versions 7.1 and 8.3 as compared to Geant4 version 6.1 with respect to data distributions of: the hit residuals of tracks in BABAR silicon vertex tracker; the photon and K{sub L}{sup 0} shower shapes in the electromagnetic calorimeter; the ratio of energy deposited in the electromagnetic calorimeter and the flux return of the magnet instrumented with a muon detection system composed of resistive plate chambers and limited-streamer tubes; and the muon identification efficiency in the muon detector system of the BABAR detector.

  13. Geant4-DNA simulations using complex DNA geometries generated by the DnaFabric tool

    NASA Astrophysics Data System (ADS)

    Meylan, S.; Vimont, U.; Incerti, S.; Clairand, I.; Villagrasa, C.

    2016-07-01

    Several DNA representations are used to study radio-induced complex DNA damages depending on the approach and the required level of granularity. Among all approaches, the mechanistic one requires the most resolved DNA models that can go down to atomistic DNA descriptions. The complexity of such DNA models make them hard to modify and adapt in order to take into account different biological conditions. The DnaFabric project was started to provide a tool to generate, visualise and modify such complex DNA models. In the current version of DnaFabric, the models can be exported to the Geant4 code to be used as targets in the Monte Carlo simulation. In this work, the project was used to generate two DNA fibre models corresponding to two DNA compaction levels representing the hetero and the euchromatin. The fibres were imported in a Geant4 application where computations were performed to estimate the influence of the DNA compaction on the amount of calculated DNA damage. The relative difference of the DNA damage computed in the two fibres for the same number of projectiles was found to be constant and equal to 1.3 for the considered primary particles (protons from 300 keV to 50 MeV). However, if only the tracks hitting the DNA target are taken into account, then the relative difference is more important for low energies and decreases to reach zero around 10 MeV. The computations were performed with models that contain up to 18,000 DNA nucleotide pairs. Nevertheless, DnaFabric will be extended to manipulate multi-scale models that go from the molecular to the cellular levels.

  14. Monte carlo simulations of the n_TOF lead spallation target with the Geant4 toolkit: A benchmark study

    NASA Astrophysics Data System (ADS)

    Lerendegui-Marco, J.; Cortés-Giraldo, M. A.; Guerrero, C.; Quesada, J. M.; Meo, S. Lo; Massimi, C.; Barbagallo, M.; Colonna, N.; Mancussi, D.; Mingrone, F.; Sabaté-Gilarte, M.; Vannini, G.; Vlachoudis, V.; Aberle, O.; Andrzejewski, J.; Audouin, L.; Bacak, M.; Balibrea, J.; Bečvář, F.; Berthoumieux, E.; Billowes, J.; Bosnar, D.; Brown, A.; Caamaño, M.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Cardella, R.; Casanovas, A.; Cerutti, F.; Chen, Y. H.; Chiaveri, E.; Cortés, G.; Cosentino, L.; Damone, L. A.; Diakaki, M.; Domingo-Pardo, C.; Dressler, R.; Dupont, E.; Durán, I.; Fernández-Domínguez, B.; Ferrari, A.; Ferreira, P.; Finocchiaro, P.; Göbel, K.; Gómez-Hornillos, M. B.; García, A. R.; Gawlik, A.; Gilardoni, S.; Glodariu, T.; Gonçalves, I. F.; González, E.; Griesmayer, E.; Gunsing, F.; Harada, H.; Heinitz, S.; Heyse, J.; Jenkins, D. G.; Jericha, E.; Käppeler, F.; Kadi, Y.; Kalamara, A.; Kavrigin, P.; Kimura, A.; Kivel, N.; Kokkoris, M.; Krtička, M.; Kurtulgil, D.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Lonsdale, S. J.; Macina, D.; Marganiec, J.; Martínez, T.; Masi, A.; Mastinu, P.; Mastromarco, M.; Maugeri, E. A.; Mazzone, A.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Musumarra, A.; Negret, A.; Nolte, R.; Oprea, A.; Patronis, N.; Pavlik, A.; Perkowski, J.; Porras, I.; Praena, J.; Radeck, D.; Rauscher, T.; Reifarth, R.; Rout, P. C.; Rubbia, C.; Ryan, J. A.; Saxena, A.; Schillebeeckx, P.; Schumann, D.; Smith, A. G.; Sosnin, N. V.; Stamatopoulos, A.; Tagliente, G.; Tain, J. L.; Tarifeño-Saldivia, A.; Tassan-Got, L.; Valenta, S.; Variale, V.; Vaz, P.; Ventura, A.; Vlastou, R.; Wallner, A.; Warren, S.; Woods, P. J.; Wright, T.; Žugec, P.

    2017-09-01

    Monte Carlo (MC) simulations are an essential tool to determine fundamental features of a neutron beam, such as the neutron flux or the γ-ray background, that sometimes can not be measured or at least not in every position or energy range. Until recently, the most widely used MC codes in this field had been MCNPX and FLUKA. However, the Geant4 toolkit has also become a competitive code for the transport of neutrons after the development of the native Geant4 format for neutron data libraries, G4NDL. In this context, we present the Geant4 simulations of the neutron spallation target of the n_TOF facility at CERN, done with version 10.1.1 of the toolkit. The first goal was the validation of the intra-nuclear cascade models implemented in the code using, as benchmark, the characteristics of the neutron beam measured at the first experimental area (EAR1), especially the neutron flux and energy distribution, and the time distribution of neutrons of equal kinetic energy, the so-called Resolution Function. The second goal was the development of a Monte Carlo tool aimed to provide useful calculations for both the analysis and planning of the upcoming measurements at the new experimental area (EAR2) of the facility.

  15. Optimization of a photoneutron source based on 10 MeV electron beam using Geant4 Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Askri, Boubaker

    2015-10-01

    Geant4 Monte Carlo code has been used to conceive and optimize a simple and compact neutron source based on a 10 MeV electron beam impinging on a tungsten target adjoined to a beryllium target. For this purpose, a precise photonuclear reaction cross-section model issued from the International Atomic Energy Agency (IAEA) database was linked to Geant4 to accurately simulate the interaction of low energy bremsstrahlung photons with beryllium material. A benchmark test showed that a good agreement was achieved when comparing the emitted neutron flux spectra predicted by Geant4 and Fluka codes for a beryllium cylinder bombarded with a 5 MeV photon beam. The source optimization was achieved through a two stage Monte Carlo simulation. In the first stage, the distributions of the seven phase space coordinates of the bremsstrahlung photons at the boundaries of the tungsten target were determined. In the second stage events corresponding to photons emitted according to these distributions were tracked. A neutron yield of 4.8 × 1010 neutrons/mA/s was obtained at 20 cm from the beryllium target. A thermal neutron yield of 1.5 × 109 neutrons/mA/s was obtained after introducing a spherical shell of polyethylene as a neutron moderator.

  16. Radiation quality of cosmic ray nuclei studied with Geant4-based simulations

    NASA Astrophysics Data System (ADS)

    Burigo, Lucas N.; Pshenichnov, Igor A.; Mishustin, Igor N.; Bleicher, Marcus

    2014-04-01

    In future missions in deep space a space craft will be exposed to a non-negligible flux of high charge and energy (HZE) particles present in the galactic cosmic rays (GCR). One of the major concerns of manned missions is the impact on humans of complex radiation fields which result from the interactions of HZE particles with the spacecraft materials. The radiation quality of several ions representing GCR is investigated by calculating microdosimetry spectra. A Geant4-based Monte Carlo model for Heavy Ion Therapy (MCHIT) is used to simulate microdosimetry data for HZE particles in extended media where fragmentation reactions play a certain role. Our model is able to reproduce measured microdosimetry spectra for H, He, Li, C and Si in the energy range of 150-490 MeV/u. The effect of nuclear fragmentation on the relative biological effectiveness (RBE) of He, Li and C is estimated and found to be below 10%.

  17. A computationally effcient moment-preserving Monte Carlo proton transport method in Geant4

    NASA Astrophysics Data System (ADS)

    Dixon, D. A.; Prinja, A. K.; McCartney, A. P.; Hughes, H. G.

    2017-09-01

    The moment-preserving method, demonstrated as a viable alternative to condensed history for electrons, is extended to protons. Given the generality and the flexibility of the method, a discrete Coulomb scattering and discrete impactionization differential cross-section library for protons was readily developed and existing Geant4 electron discrete process and model classes were extended to make use of the new proton library. It is shown that levels of effciency and accuracy similar to those demonstrated for electrons are obtainable for protons in straight-ahead, energy-loss problems. However, in problems with deflection, agreement is strongly dependent on the proton energy. That is, good agreement was observed in the few MeV range, while unsatisfactory agreement was observed in problems with proton energies above 100-MeV.

  18. ALGEBRA: ALgorithm for the heterogeneous dosimetry based on GEANT4 for BRAchytherapy.

    PubMed

    Afsharpour, H; Landry, G; D'Amours, M; Enger, S; Reniers, B; Poon, E; Carrier, J-F; Verhaegen, F; Beaulieu, L

    2012-06-07

    Task group 43 (TG43)-based dosimetry algorithms are efficient for brachytherapy dose calculation in water. However, human tissues have chemical compositions and densities different than water. Moreover, the mutual shielding effect of seeds on each other (interseed attenuation) is neglected in the TG43-based dosimetry platforms. The scientific community has expressed the need for an accurate dosimetry platform in brachytherapy. The purpose of this paper is to present ALGEBRA, a Monte Carlo platform for dosimetry in brachytherapy which is sufficiently fast and accurate for clinical and research purposes. ALGEBRA is based on the GEANT4 Monte Carlo code and is capable of handling the DICOM RT standard to recreate a virtual model of the treated site. Here, the performance of ALGEBRA is presented for the special case of LDR brachytherapy in permanent prostate and breast seed implants. However, the algorithm is also capable of handling other treatments such as HDR brachytherapy.

  19. ALGEBRA: ALgorithm for the heterogeneous dosimetry based on GEANT4 for BRAchytherapy

    NASA Astrophysics Data System (ADS)

    Afsharpour, H.; Landry, G.; D'Amours, M.; Enger, S.; Reniers, B.; Poon, E.; Carrier, J.-F.; Verhaegen, F.; Beaulieu, L.

    2012-06-01

    Task group 43 (TG43)-based dosimetry algorithms are efficient for brachytherapy dose calculation in water. However, human tissues have chemical compositions and densities different than water. Moreover, the mutual shielding effect of seeds on each other (interseed attenuation) is neglected in the TG43-based dosimetry platforms. The scientific community has expressed the need for an accurate dosimetry platform in brachytherapy. The purpose of this paper is to present ALGEBRA, a Monte Carlo platform for dosimetry in brachytherapy which is sufficiently fast and accurate for clinical and research purposes. ALGEBRA is based on the GEANT4 Monte Carlo code and is capable of handling the DICOM RT standard to recreate a virtual model of the treated site. Here, the performance of ALGEBRA is presented for the special case of LDR brachytherapy in permanent prostate and breast seed implants. However, the algorithm is also capable of handling other treatments such as HDR brachytherapy.

  20. Geant4 Simulation of A Multi-layered target for the Study of Neutron-Unbound Nuclei

    NASA Astrophysics Data System (ADS)

    Gueye, Paul; Freeman, Jessica; Frank, Nathan; Thoennessen, Michael; MONA Collaboration

    2013-10-01

    The MoNA/LISA setup at the National Superconducting Cyclotron Laboratory at Michigan State University has provided an avenue to study the nuclear structure of unbound states/nuclei at and beyond the neutron dripline for the past decade using secondary beams from the Coupled Cyclotron Facility. A new multi-layered Si/Be active target is being designed to specifically study neutron-unbound nuclei. In these experiments the decay energy is reconstructed from fragment-neutron coincidence measurements that are typically low in count rate. The multi-layered target will allow the use of thicker targets to increase the reaction rates, thus enabling to study currently out of reach nuclei such as 21C, 23C and 24N. The Geant4 Monte Carlo toolkit is currently used to model these physics processes within the multi-layered target and expected invariant mass distributions. A description of the experimental setup and simulation work will be discussed. This work is supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0000979.

  1. Including Delbrück scattering in GEANT4

    NASA Astrophysics Data System (ADS)

    Omer, Mohamed; Hajima, Ryoichi

    2017-08-01

    Elastic scattering of γ-rays is a significant interaction among γ-ray interactions with matter. Therefore, the planning of experiments involving measurements of γ-rays using Monte Carlo simulations usually includes elastic scattering. However, current simulation tools do not provide a complete picture of elastic scattering. The majority of these tools assume Rayleigh scattering is the primary contributor to elastic scattering and neglect other elastic scattering processes, such as nuclear Thomson and Delbrück scattering. Here, we develop a tabulation-based method to simulate elastic scattering in one of the most common open-source Monte Carlo simulation toolkits, GEANT4. We collectively include three processes, Rayleigh scattering, nuclear Thomson scattering, and Delbrück scattering. Our simulation more appropriately uses differential cross sections based on the second-order scattering matrix instead of current data, which are based on the form factor approximation. Moreover, the superposition of these processes is carefully taken into account emphasizing the complex nature of the scattering amplitudes. The simulation covers an energy range of 0.01 MeV ≤ E ≤ 3 MeV and all elements with atomic numbers of 1 ≤ Z ≤ 99. In addition, we validated our simulation by comparing the differential cross sections measured in earlier experiments with those extracted from the simulations. We find that the simulations are in good agreement with the experimental measurements. Differences between the experiments and the simulations are 21% for uranium, 24% for lead, 3% for tantalum, and 8% for cerium at 2.754 MeV. Coulomb corrections to the Delbrück amplitudes may account for the relatively large differences that appear at higher Z values.

  2. GATE - Geant4 Application for Tomographic Emission: a simulation toolkit for PET and SPECT

    PubMed Central

    Jan, S.; Santin, G.; Strul, D.; Staelens, S.; Assié, K.; Autret, D.; Avner, S.; Barbier, R.; Bardiès, M.; Bloomfield, P. M.; Brasse, D.; Breton, V.; Bruyndonckx, P.; Buvat, I.; Chatziioannou, A. F.; Choi, Y.; Chung, Y. H.; Comtat, C.; Donnarieix, D.; Ferrer, L.; Glick, S. J.; Groiselle, C. J.; Guez, D.; Honore, P.-F.; Kerhoas-Cavata, S.; Kirov, A. S.; Kohli, V.; Koole, M.; Krieguer, M.; van der Laan, D. J.; Lamare, F.; Largeron, G.; Lartizien, C.; Lazaro, D.; Maas, M. C.; Maigne, L.; Mayet, F.; Melot, F.; Merheb, C.; Pennacchio, E.; Perez, J.; Pietrzyk, U.; Rannou, F. R.; Rey, M.; Schaart, D. R.; Schmidtlein, C. R.; Simon, L.; Song, T. Y.; Vieira, J.-M.; Visvikis, D.; Van de Walle, R.; Wieërs, E.; Morel, C.

    2012-01-01

    Monte Carlo simulation is an essential tool in emission tomography that can assist in the design of new medical imaging devices, the optimization of acquisition protocols, and the development or assessment of image reconstruction algorithms and correction techniques. GATE, the Geant4 Application for Tomographic Emission, encapsulates the Geant4 libraries to achieve a modular, versatile, scripted simulation toolkit adapted to the field of nuclear medicine. In particular, GATE allows the description of time-dependent phenomena such as source or detector movement, and source decay kinetics. This feature makes it possible to simulate time curves under realistic acquisition conditions and to test dynamic reconstruction algorithms. This paper gives a detailed description of the design and development of GATE by the OpenGATE collaboration, whose continuing objective is to improve, document, and validate GATE by simulating commercially available imaging systems for PET and SPECT. Large effort is also invested in the ability and the flexibility to model novel detection systems or systems still under design. A public release of GATE licensed under the GNU Lesser General Public License can be downloaded at the address http://www-lphe.ep.ch/GATE/. Two benchmarks developed for PET and SPECT to test the installation of GATE and to serve as a tutorial for the users are presented. Extensive validation of the GATE simulation platform has been started, comparing simulations and measurements on commercially available acquisition systems. References to those results are listed. The future prospects toward the gridification of GATE and its extension to other domains such as dosimetry are also discussed. PMID:15552416

  3. Evaluation of a commercial MRI Linac based Monte Carlo dose calculation algorithm with GEANT 4

    SciTech Connect

    Ahmad, Syed Bilal; Sarfehnia, Arman; Kim, Anthony; Sahgal, Arjun; Keller, Brian; Paudel, Moti Raj; Hissoiny, Sami

    2016-02-15

    Purpose: This paper provides a comparison between a fast, commercial, in-patient Monte Carlo dose calculation algorithm (GPUMCD) and GEANT4. It also evaluates the dosimetric impact of the application of an external 1.5 T magnetic field. Methods: A stand-alone version of the Elekta™ GPUMCD algorithm, to be used within the Monaco treatment planning system to model dose for the Elekta™ magnetic resonance imaging (MRI) Linac, was compared against GEANT4 (v10.1). This was done in the presence or absence of a 1.5 T static magnetic field directed orthogonally to the radiation beam axis. Phantoms with material compositions of water, ICRU lung, ICRU compact-bone, and titanium were used for this purpose. Beams with 2 MeV monoenergetic photons as well as a 7 MV histogrammed spectrum representing the MRI Linac spectrum were emitted from a point source using a nominal source-to-surface distance of 142.5 cm. Field sizes ranged from 1.5 × 1.5 to 10 × 10 cm{sup 2}. Dose scoring was performed using a 3D grid comprising 1 mm{sup 3} voxels. The production thresholds were equivalent for both codes. Results were analyzed based upon a voxel by voxel dose difference between the two codes and also using a volumetric gamma analysis. Results: Comparisons were drawn from central axis depth doses, cross beam profiles, and isodose contours. Both in the presence and absence of a 1.5 T static magnetic field the relative differences in doses scored along the beam central axis were less than 1% for the homogeneous water phantom and all results matched within a maximum of ±2% for heterogeneous phantoms. Volumetric gamma analysis indicated that more than 99% of the examined volume passed gamma criteria of 2%—2 mm (dose difference and distance to agreement, respectively). These criteria were chosen because the minimum primary statistical uncertainty in dose scoring voxels was 0.5%. The presence of the magnetic field affects the dose at the interface depending upon the density of the material

  4. Evaluation of a commercial MRI Linac based Monte Carlo dose calculation algorithm with GEANT4.

    PubMed

    Ahmad, Syed Bilal; Sarfehnia, Arman; Paudel, Moti Raj; Kim, Anthony; Hissoiny, Sami; Sahgal, Arjun; Keller, Brian

    2016-02-01

    This paper provides a comparison between a fast, commercial, in-patient Monte Carlo dose calculation algorithm (GPUMCD) and geant4. It also evaluates the dosimetric impact of the application of an external 1.5 T magnetic field. A stand-alone version of the Elekta™ GPUMCD algorithm, to be used within the Monaco treatment planning system to model dose for the Elekta™ magnetic resonance imaging (MRI) Linac, was compared against GEANT4 (v10.1). This was done in the presence or absence of a 1.5 T static magnetic field directed orthogonally to the radiation beam axis. Phantoms with material compositions of water, ICRU lung, ICRU compact-bone, and titanium were used for this purpose. Beams with 2 MeV monoenergetic photons as well as a 7 MV histogrammed spectrum representing the MRI Linac spectrum were emitted from a point source using a nominal source-to-surface distance of 142.5 cm. Field sizes ranged from 1.5 × 1.5 to 10 × 10 cm(2). Dose scoring was performed using a 3D grid comprising 1 mm(3) voxels. The production thresholds were equivalent for both codes. Results were analyzed based upon a voxel by voxel dose difference between the two codes and also using a volumetric gamma analysis. Comparisons were drawn from central axis depth doses, cross beam profiles, and isodose contours. Both in the presence and absence of a 1.5 T static magnetic field the relative differences in doses scored along the beam central axis were less than 1% for the homogeneous water phantom and all results matched within a maximum of ±2% for heterogeneous phantoms. Volumetric gamma analysis indicated that more than 99% of the examined volume passed gamma criteria of 2%-2 mm (dose difference and distance to agreement, respectively). These criteria were chosen because the minimum primary statistical uncertainty in dose scoring voxels was 0.5%. The presence of the magnetic field affects the dose at the interface depending upon the density of the material on either sides of the interface

  5. Study on GEANT4 code applications to dose calculation using imaging data

    NASA Astrophysics Data System (ADS)

    Lee, Jeong Ok; Kang, Jeong Ku; Kim, Jhin Kee; Kwon, Hyeong Cheol; Kim, Jung Soo; Kim, Bu Gil; Jeong, Dong Hyeok

    2015-07-01

    The use of the GEANT4 code has increased in the medical field. Various studies have calculated the patient dose distributions by users the GEANT4 code with imaging data. In present study, Monte Carlo simulations based on DICOM data were performed to calculate the dose absorb in the patient's body. Various visualization tools are installed in the GEANT4 code to display the detector construction; however, the display of DICOM images is limited. In addition, to displaying the dose distributions on the imaging data of the patient is difficult. Recently, the gMocren code, a volume visualization tool for GEANT4 simulation, was developed and has been used in volume visualization of image files. In this study, the imaging based on the dose distributions absorbed in the patients was performed by using the gMocren code. Dosimetric evaluations with were carried out by using thermo luminescent dosimeter and film dosimetry to verify the calculated results.

  6. Comparison of GATE/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV

    NASA Astrophysics Data System (ADS)

    Maigne, L.; Perrot, Y.; Schaart, D. R.; Donnarieix, D.; Breton, V.

    2011-02-01

    The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between 15 keV and 20 MeV by means of GATE 6.0, which makes use of the GEANT4 version 9.2 Standard Electromagnetic Physics Package. The results are compared to the well-validated codes EGSnrc and MCNP4C. It is shown that recent improvements made to the GEANT4/GATE software result in significantly better agreement with the other codes. We furthermore illustrate several issues of general interest to GATE and GEANT4 users who wish to perform accurate simulations involving electrons. Provided that the electron step size is sufficiently restricted, GATE 6.0 and EGSnrc dose point kernels are shown to agree to within less than 3% of the maximum dose between 50 keV and 4 MeV, while pencil beam kernels are found to agree to within less than 4% of the maximum dose between 15 keV and 20 MeV.

  7. Monte Carlo simulation and scatter correction of the GE advance PET scanner with SimSET and Geant4.

    PubMed

    Barret, Olivier; Carpenter, T Adrian; Clark, John C; Ansorge, Richard E; Fryer, Tim D

    2005-10-21

    For Monte Carlo simulations to be used as an alternative solution to perform scatter correction, accurate modelling of the scanner as well as speed is paramount. General-purpose Monte Carlo packages (Geant4, EGS, MCNP) allow a detailed description of the scanner but are not efficient at simulating voxel-based geometries (patient images). On the other hand, dedicated codes (SimSET, PETSIM) will perform well for voxel-based objects but will be poor in their capacity of simulating complex geometries such as a PET scanner. The approach adopted in this work was to couple a dedicated code (SimSET) with a general-purpose package (Geant4) to have the efficiency of the former and the capabilities of the latter. The combined SimSET+Geant4 code (SimG4) was assessed on the GE Advance PET scanner and compared to the use of SimSET only. A better description of the resolution and sensitivity of the scanner and of the scatter fraction was obtained with SimG4. The accuracy of scatter correction performed with SimG4 and SimSET was also assessed from data acquired with the 20 cm NEMA phantom. SimG4 was found to outperform SimSET and to give slightly better results than the GE scatter correction methods installed on the Advance scanner (curve fitting and scatter modelling for the 300-650 keV and 375-650 keV energy windows, respectively). In the presence of a hot source close to the edge of the field of view (as found in oxygen scans), the GE curve-fitting method was found to fail whereas SimG4 maintained its performance.

  8. Monte Carlo simulation and scatter correction of the GE Advance PET scanner with SimSET and Geant4

    NASA Astrophysics Data System (ADS)

    Barret, Olivier; Carpenter, T. Adrian; Clark, John C.; Ansorge, Richard E.; Fryer, Tim D.

    2005-10-01

    For Monte Carlo simulations to be used as an alternative solution to perform scatter correction, accurate modelling of the scanner as well as speed is paramount. General-purpose Monte Carlo packages (Geant4, EGS, MCNP) allow a detailed description of the scanner but are not efficient at simulating voxel-based geometries (patient images). On the other hand, dedicated codes (SimSET, PETSIM) will perform well for voxel-based objects but will be poor in their capacity of simulating complex geometries such as a PET scanner. The approach adopted in this work was to couple a dedicated code (SimSET) with a general-purpose package (Geant4) to have the efficiency of the former and the capabilities of the latter. The combined SimSET+Geant4 code (SimG4) was assessed on the GE Advance PET scanner and compared to the use of SimSET only. A better description of the resolution and sensitivity of the scanner and of the scatter fraction was obtained with SimG4. The accuracy of scatter correction performed with SimG4 and SimSET was also assessed from data acquired with the 20 cm NEMA phantom. SimG4 was found to outperform SimSET and to give slightly better results than the GE scatter correction methods installed on the Advance scanner (curve fitting and scatter modelling for the 300-650 keV and 375-650 keV energy windows, respectively). In the presence of a hot source close to the edge of the field of view (as found in oxygen scans), the GE curve-fitting method was found to fail whereas SimG4 maintained its performance.

  9. Guiding the Design of Radiation Imagers with Experimentally Benchmarked Geant4 Simulations for Electron-Tracking Compton Imaging

    NASA Astrophysics Data System (ADS)

    Coffer, Amy Beth

    -scattered electron-trajectories is with high-resolution Charged-Coupled Devices (CCDs). The proof-of-principle CCD-based ETCI experiment demonstrated the CCDs' ability to measure the Compton-scattered electron-tracks as a 2-dimensional image. Electron-track-imaging algorithms using the electron-track-image are able to determine the 3-dimensional electron-track trajectory within +/- 20 degrees. The work presented here is the physics simulations developed along side the experimental proof-of-principle experiment. The development of accurate physics modeling for multiple-layer CCDs based ETCI systems allow for the accurate prediction of future ETCI system performance. The simulations also enable quick development insights for system design, and they guide the development of electron-track reconstruction methods. The physics simulation efforts for this project looked closely at the accuracy of the Geant4 Monte Carlo methods for medium energy electron transport. In older version of Geant4 there were some discrepancies between the electron-tracking experimental measurements and the simulation results. It was determined that when comparing the electron dynamics of electrons at very high resolutions, Geant4 simulations must be fine tuned with careful choices for physics production cuts and electron physics stepping sizes. One result of this work is a CCDs Monte Carlo model that has been benchmarked to experimental findings and fully characterized for both photon and electron transport. The CCDs physics model now match to within 1 percent error of experimental results for scattered-electron energies below 500 keV. Following the improvements of the CCDs simulations, the performance of a realistic two-layer CCD-stack system was characterized. The realistic CCD-stack system looked at the effect of thin passive-layers on the CCDs' front face and back-contact. The photon interaction efficiency was calculated for the two-layer CCD-stack, and we found that there is a 90 percent probability of

  10. SU-E-T-427: Feasibility Study for Evaluation of IMRT Dose Distribution Using Geant4-Based Automated Algorithms

    SciTech Connect

    Choi, H; Shin, W; Testa, M; Min, C; Kim, J

    2015-06-15

    Purpose: For intensity-modulated radiation therapy (IMRT) treatment planning validation using Monte Carlo (MC) simulations, a precise and automated procedure is necessary to evaluate the patient dose distribution. The aim of this study is to develop an automated algorithm for IMRT simulations using DICOM files and to evaluate the patient dose based on 4D simulation using the Geant4 MC toolkit. Methods: The head of a clinical linac (Varian Clinac 2300 IX) was modeled in Geant4 along with particular components such as the flattening filter and the multi-leaf collimator (MLC). Patient information and the position of the MLC were imported from the DICOM-RT interface. For each position of the MLC, a step- and-shoot technique was adopted. PDDs and lateral profiles were simulated in a water phantom (50×50×40 cm{sup 3}) and compared to measurement data. We used a lung phantom and MC-dose calculations were compared to the clinical treatment planning used at the Seoul National University Hospital. Results: In order to reproduce the measurement data, we tuned three free parameters: mean and standard deviation of the primary electron beam energy and the beam spot size. These parameters for 6 MV were found to be 5.6 MeV, 0.2378 MeV and 1 mm FWHM respectively. The average dose difference between measurements and simulations was less than 2% for PDDs and radial profiles. The lung phantom study showed fairly good agreement between MC and planning dose despite some unavoidable statistical fluctuation. Conclusion: The current feasibility study using the lung phantom shows the potential for IMRT dose validation using 4D MC simulations using Geant4 tool kits. This research was supported by Korea Institute of Nuclear safety and Development of Measurement Standards for Medical Radiation funded by Korea research Institute of Standards and Science. (KRISS-2015-15011032)

  11. Interaction of Fast Nucleons with Actinide Nuclei Studied with GEANT4

    NASA Astrophysics Data System (ADS)

    Malyshkin, Yu.; Pshenichnov, I.; Mishustin, I.; Greiner, W.

    2014-04-01

    We model interactions of protons and neutrons with energies from 1 to 1000 MeV with 241Am and 243Am nuclei. The calculations are performed with the Monte Carlo model for Accelerator Driven Systems (MCADS) which we developed based on the GEANT4 toolkit of version 9.4. This toolkit is widely used to simulate the propagation of particles in various materials which contain nuclei up to uranium. After several extensions we apply this toolkit also to proton- and neutron-induced reactions on Am. The fission and radiative neutron capture cross sections, neutron multiplicities and distributions of fission fragments were calculated for 241Am and 243Am and compared with experimental data. As demonstrated, the fission of americium by energetic protons with energies above 20 MeV can be well described by the Intra-Nuclear Cascade Liège (INCL) model combined with the fission-evaporation model ABLA. The calculated average numbers of fission neutrons and mass distributions of fission products agree well with the corresponding data. However, the proton-induced fission below 20 MeV is described less accurately. This is attributed to the limitations of the Intra-Nuclear Cascade model at low projectile energies.

  12. Simulation and Digitization of a Gas Electron Multiplier Detector Using Geant4 and an Object-Oriented Digitization Program

    NASA Astrophysics Data System (ADS)

    McMullen, Timothy; Liyanage, Nilanga; Xiong, Weizhi; Zhao, Zhiwen

    2017-01-01

    Our research has focused on simulating the response of a Gas Electron Multiplier (GEM) detector using computational methods. GEM detectors provide a cost effective solution for radiation detection in high rate environments. A detailed simulation of GEM detector response to radiation is essential for the successful adaption of these detectors to different applications. Using Geant4 Monte Carlo (GEMC), a wrapper around Geant4 which has been successfully used to simulate the Solenoidal Large Intensity Device (SoLID) at Jefferson Lab, we are developing a simulation of a GEM chamber similar to the detectors currently used in our lab. We are also refining an object-oriented digitization program, which translates energy deposition information from GEMC into electronic readout which resembles the readout from our physical detectors. We have run the simulation with beta particles produced by the simulated decay of a 90Sr source, as well as with a simulated bremsstrahlung spectrum. Comparing the simulation data with real GEM data taken under similar conditions is used to refine the simulation parameters. Comparisons between results from the simulations and results from detector tests will be presented.

  13. Microdosimetry of the Auger electron emitting 123I radionuclide using Geant4-DNA simulations.

    PubMed

    Fourie, H; Newman, R T; Slabbert, J P

    2015-04-21

    Microdosimetric calculations of the Auger electron emitter (123)I were done in liquid water spheres using the Geant4 toolkit. The electron emission spectrum of (123)I produced by Geant4 is presented. Energy deposition and corresponding S-values were calculated to investigate the influence of the sub-cellular localization of the Auger emitter. It was found that S-values calculated by the Geant4 toolkit are generally lower than the values calculated by other Monte Carlo codes for the (123)I radionuclide. The differences in the compared S-values are mainly due to the different particle emission spectra employed by the respective computational codes and emphasizes the influence of the spectra on dosimetry calculations.

  14. Simulation of ultrasoft X-rays induced DNA damage using the Geant4 Monte Carlo toolkit

    NASA Astrophysics Data System (ADS)

    Tajik, Marjan; Rozatian, Amir S. H.; Semsarha, Farid

    2015-01-01

    In this study, the total yields of SSB and DSB induced by monoenergetic electrons with energies of 0.28-4.55 keV, corresponding to ultrasoft X-rays energies, have been calculated in Charlton and Humm volume model using the Geant4-DNA toolkit and compared with theoretical and experimental data. A reasonable agreement between the obtained results in the present study and experimental and theoretical data of previous studies showed the efficiency of this model in estimating the total yield of strand breaks in spite of its simplicity. Also, it has been found that in the low energy region, the yield of the total SSB remains nearly constant while the DSB yield increases with decreasing energy. Moreover, a direct dependency between DSB induction, RBE value and the mean lineal energy as a microdosimetry quantity has been observed. In addition, it has become clear that the use of the threshold energy of 10.79 eV to calculate the total strand breaks yields results in a better agreement with the experiments, while the threshold of 17.5 eV shows a big difference.

  15. GEANT4 Simulations of Gamma-Gamma Angular Correlations with GRIFFIN

    NASA Astrophysics Data System (ADS)

    Natzke, Connor; Griffin Collaboration

    2016-09-01

    The structure of very neutron rich isotopes has been of recent experimental interest for both nuclear astrophysics and fundamental nuclear structure investigations. In beta-minus decay specifically, beta-delayed gamma cascades can help to shed light on the spin and parity of the states involved. One of the world's most powerful decay spectroscopy tool is the Gamma-Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at TRIUMF-ISAC in Vancouver, Canada. To investigate the feasibility of these experimental studies, GEANT4 simulations of neutron-rich nuclei are critical, as they are able to provide realistic estimates of what the experimental results may look like. The first such nucleus investigated was 44P, and both the temporal and angular γγ correlations were extracted. Furthermore the simulations were used to model various multipole decay possibilities which provide a powerful tool analyzing collected data from such facilities. In the future, the Facility for Rare Isotope Beams (FRIB) at MSU will be an ideal site for such studies on the most exotic nuclei.

  16. Muon Telescope (MuTe): A first study using Geant4

    NASA Astrophysics Data System (ADS)

    Asorey, H.; Balaguera-Rojas, A.; Calderon-Ardila, R.; Núñez, L. A.; Sanabria-Gómez, J. D.; Súarez-Durán, M.; Tapia, A.

    2017-07-01

    Muon tomography is based on recording the difference of absorption of muons by matter, as ordinary radiography does for using X-rays. The interaction of cosmic rays with the atmosphere produces extensive air showers which provides an abundant source for atmospheric muons, benefiting various applications of muon tomography, particularly the study of the inner structure of volcanoes. The MuTe (for Muon Telescope) is a hybrid detector composed of scintillation bars and a water Cherenkov detector designed to measure cosmic muon flux crossing volcanic edifices. This detector consists of two scintillator plates (1.44 m2 with 30 x 30 pixels), with a maximum distance of 2.0m of separation. In this work we report the first simulation of the MuTe using GEANT4 -set of simulation tools, based in C++ - that provides information about the interaction between radiation and matter. This computational tool allows us to know the energy deposited by the muons and modeling the response of the scintillators and the water cherenkov detector to the passage of radiation which is crucial to compare to our data analysis.

  17. Optimization of a general-purpose, actively scanned proton beamline for ocular treatments: Geant4 simulations.

    PubMed

    Piersimoni, Pierluigi; Rimoldi, Adele; Riccardi, Cristina; Pirola, Michele; Molinelli, Silvia; Ciocca, Mario

    2015-03-08

    The Italian National Center for Hadrontherapy (CNAO, Centro Nazionale di Adroterapia Oncologica), a synchrotron-based hospital facility, started the treatment of patients within selected clinical trials in late 2011 and 2012 with actively scanned proton and carbon ion beams, respectively. The activation of a new clinical protocol for the irradiation of uveal melanoma using the existing general-purpose proton beamline is foreseen for late 2014. Beam characteristics and patient treatment setup need to be tuned to meet the specific requirements for such a type of treatment technique. The aim of this study is to optimize the CNAO transport beamline by adding passive components and minimizing air gap to achieve the optimal conditions for ocular tumor irradiation. The CNAO setup with the active and passive components along the transport beamline, as well as a human eye-modeled detector also including a realistic target volume, were simulated using the Monte Carlo Geant4 toolkit. The strong reduction of the air gap between the nozzle and patient skin, as well as the insertion of a range shifter plus a patient-specific brass collimator at a short distance from the eye, were found to be effective tools to be implemented. In perspective, this simulation toolkit could also be used as a benchmark for future developments and testing purposes on commercial treatment planning systems.

  18. Monte Carlo simulation of laser beams interaction with the human eye using Geant4.

    PubMed

    Tendeiro, Diogo; Lopes, Gonçalo; Vieira, Pedro; Santos, José Paulo

    2014-05-07

    Due to the unique characteristics of the eye, ophthalmologic diagnostic techniques often rely on the photons interaction with the retina to infer its internal structure. Although these techniques are widely used, the interpretation of the generated images is not always fully understood, as in scanning laser ophthalmoscopy dark field imaging. This limits the exploitation of its full potential as a diagnostic tool for deep abnormalities in the retina, as in the situation of drusen. With the aim of better understanding the retinal diagnostic images, we have carried out computer simulations of incident laser beams interacting with different structures of the human eye, including a retina with and without drusen. We have used the Geant4 simulation toolkit, applying the optical package of the electromagnetic (EM) physics working group, to simulate the physical processes of reflection, refraction, absorption, and scattering of low energy photons (2 eV) in biological tissues. For each simulation it was used a single beam of orange light, with a Gaussian profile, that travels through all optical elements of the eye. The reflected beam characteristics were analyzed by virtual detectors in different locations, which collected information about the number and position of photons. The geometry and optical properties of all components of the eye were considered according to the published data. Simulation results put in evidence that the presence of drusen influences the profile of the reflected beams. It changes the mean free path of the photons, modifying its reflection pattern, which depends on the area illuminated by the incident beam. This result is also visible when the reflected beam is analyzed outside of the eye, when the profile has no longer a symmetrical Gaussian distribution. These results will support the retinal diagnostic images that will be obtained in a near future with a new developed ophthalmic apparatus. The shape analysis of the reflected beams in retinal

  19. Quantification of the validity of simulations based on Geant4 and FLUKA for photo-nuclear interactions in the high energy range

    NASA Astrophysics Data System (ADS)

    Quintieri, Lina; Pia, Maria Grazia; Augelli, Mauro; Saracco, Paolo; Capogni, Marco; Guarnieri, Guido

    2017-09-01

    Photo-nuclear interactions are relevant in many research fields of both fundamental and applied physics and, for this reason, accurate Monte Carlo simulations of photo-nuclear interactions can provide a valuable and indispensable support in a wide range of applications (i.e from the optimisation of photo-neutron source target to the dosimetric estimation in high energy accelerator, etc). Unfortunately, few experimental photo-nuclear data are available above 100 MeV, so that, in the high energy range (from hundreds of MeV up to GeV scale), the code predictions are based on physical models. The aim of this work is to compare the predictions of relevant observables involving photon-nuclear interaction modelling, obtained with GEANT4 and FLUKA, to experimental data (if available), in order to assess the code estimation reliability, over a wide energy range. In particular, the comparison of the estimated photo-neutron yields and energy spectra with the experimental results of the n@BTF experiment (carried out at the Beam Test Facility of DaΦne collider, in Frascati, Italy) is here reported and discussed. Moreover, the preliminary results of the comparison of the cross sections used in the codes with the"evaluated' data recommended by the IAEA are also presented for some selected cases (W, Pb, Zn).

  20. SU-E-J-72: Geant4 Simulations of Spot-Scanned Proton Beam Treatment Plans

    SciTech Connect

    Kanehira, T; Sutherland, K; Matsuura, T; Umegaki, K; Shirato, H

    2014-06-01

    Purpose: To evaluate density inhomogeneities which can effect dose distributions for real-time image gated spot-scanning proton therapy (RGPT), a dose calculation system, using treatment planning system VQA (Hitachi Ltd., Tokyo) spot position data, was developed based on Geant4. Methods: A Geant4 application was developed to simulate spot-scanned proton beams at Hokkaido University Hospital. A CT scan (0.98 × 0.98 × 1.25 mm) was performed for prostate cancer treatment with three or four inserted gold markers (diameter 1.5 mm, volume 1.77 mm3) in or near the target tumor. The CT data was read into VQA. A spot scanning plan was generated and exported to text files, specifying the beam energy and position of each spot. The text files were converted and read into our Geant4-based software. The spot position was converted into steering magnet field strength (in Tesla) for our beam nozzle. Individual protons were tracked from the vacuum chamber, through the helium chamber, steering magnets, dose monitors, etc., in a straight, horizontal line. The patient CT data was converted into materials with variable density and placed in a parametrized volume at the isocenter. Gold fiducial markers were represented in the CT data by two adjacent voxels (volume 2.38 mm3). 600,000 proton histories were tracked for each target spot. As one beam contained about 1,000 spots, approximately 600 million histories were recorded for each beam on a blade server. Two plans were considered: two beam horizontal opposed (90 and 270 degree) and three beam (0, 90 and 270 degree). Results: We are able to convert spot scanning plans from VQA and simulate them with our Geant4-based code. Our system can be used to evaluate the effect of dose reduction caused by gold markers used for RGPT. Conclusion: Our Geant4 application is able to calculate dose distributions for spot scanned proton therapy.

  1. Simulation of a 6 MV Elekta Precise Linac photon beam using GATE/GEANT4

    NASA Astrophysics Data System (ADS)

    Grevillot, L.; Frisson, T.; Maneval, D.; Zahra, N.; Badel, J.-N.; Sarrut, D.

    2011-02-01

    The GEANT4-based GATE Monte Carlo (MC) platform was initially focused on PET and SPECT simulations. The new release v6.0 (February 2010) proposes new tools dedicated for radiation therapy simulations. In this work, we investigated some part of this extension and proposed a general methodology for Linac simulations. Details of the modeling of a 6 MV photon beam delivered by an Elekta Precise Linac, with radiation fields ranging from 5 × 5 to 30 × 30 cm2 at the isocenter are presented. Comparisons were performed with measurements in water. The simulations were performed in two stages: first, the patient-independent part was simulated and a phase space (PhS) was built above the secondary collimator. Then, a multiple source model (MSM) derived from the PhS was proposed to simulate the photon fluence interacting with the patient-dependent part. The selective bremsstrahlung splitting (SBS) variance reduction technique proposed in GATE was used in order to speed up the accelerator head simulation. Further investigations showed that the SBS can be safely used without biasing the simulations. Additional comparisons with full simulations performed on the EGEE grid, in a single stage from the electron source to the water phantom, allowed the evaluation of the MSM. The proposed MSM allowed for calculating depth dose and transverse profiles in 48 hours on a single 2.8 GHz CPU, with a statistical uncertainty of 0.8% for a 10 × 10 cm2 radiation field, using voxels of 5 × 5 × 5 mm3. Good agreement between simulations and measurements in water was observed, with dose differences of about 1% and 2% for depth doses and dose profiles, respectively. Additional gamma index comparisons were performed; more than 90% of the points for all simulations passed the 3%/3 mm gamma criterion. To our knowledge, this feasibility study is the first one illustrating the potential of GATE for external radiotherapy applications.

  2. Simulation of a 6 MV Elekta Precise Linac photon beam using GATE/GEANT4.

    PubMed

    Grevillot, L; Frisson, T; Maneval, D; Zahra, N; Badel, J-N; Sarrut, D

    2011-02-21

    The GEANT4-based GATE Monte Carlo (MC) platform was initially focused on PET and SPECT simulations. The new release v6.0 (February 2010) proposes new tools dedicated for radiation therapy simulations. In this work, we investigated some part of this extension and proposed a general methodology for Linac simulations. Details of the modeling of a 6 MV photon beam delivered by an Elekta Precise Linac, with radiation fields ranging from 5 × 5 to 30 × 30 cm(2) at the isocenter are presented. Comparisons were performed with measurements in water. The simulations were performed in two stages: first, the patient-independent part was simulated and a phase space (PhS) was built above the secondary collimator. Then, a multiple source model (MSM) derived from the PhS was proposed to simulate the photon fluence interacting with the patient-dependent part. The selective bremsstrahlung splitting (SBS) variance reduction technique proposed in GATE was used in order to speed up the accelerator head simulation. Further investigations showed that the SBS can be safely used without biasing the simulations. Additional comparisons with full simulations performed on the EGEE grid, in a single stage from the electron source to the water phantom, allowed the evaluation of the MSM. The proposed MSM allowed for calculating depth dose and transverse profiles in 48 hours on a single 2.8 GHz CPU, with a statistical uncertainty of 0.8% for a 10 × 10 cm(2) radiation field, using voxels of 5 × 5 × 5 mm(3). Good agreement between simulations and measurements in water was observed, with dose differences of about 1% and 2% for depth doses and dose profiles, respectively. Additional gamma index comparisons were performed; more than 90% of the points for all simulations passed the 3%/3 mm gamma criterion. To our knowledge, this feasibility study is the first one illustrating the potential of GATE for external radiotherapy applications.

  3. Geant4 Analysis of a Thermal Neutron Real-Time Imaging System

    NASA Astrophysics Data System (ADS)

    Datta, Arka; Hawari, Ayman I.

    2017-07-01

    Thermal neutron imaging is a technique for nondestructive testing providing complementary information to X-ray imaging for a wide range of applications in science and engineering. Advancement of electronic imaging systems makes it possible to obtain neutron radiographs in real time. This method requires a scintillator to convert neutrons to optical photons and a charge-coupled device (CCD) camera to detect those photons. Alongside, a well collimated beam which reduces geometrical blurriness, the use of a thin scintillator can improve the spatial resolution significantly. A representative scintillator that has been applied widely for thermal neutron imaging is 6LiF:ZnS (Ag). In this paper, a multiphysics simulation approach for designing thermal neutron imaging system is investigated. The Geant4 code is used to investigate the performance of a thermal neutron imaging system starting with a neutron source and including the production of charged particles and optical photons in the scintillator and their transport for image formation in the detector. The simulation geometry includes the neutron beam collimator and sapphire filter. The 6LiF:ZnS (Ag) scintillator is modeled along with a pixelated detector for image recording. The spatial resolution of the system was obtained as the thickness of the scintillator screen was varied between 50 and 400 μm. The results of the simulation were compared to experimental results, including measurements performed using the PULSTAR nuclear reactor imaging beam, showing good agreement. Using the established model, further examination showed that the resolution contribution of the scintillator screen is correlated with its thickness and the range of the neutron absorption reaction products (i.e., the alpha and triton particles). Consequently, thinner screens exhibit improved spatial resolution. However, this will compromise detection efficiency due to the reduced probability of neutron absorption.

  4. Estimation of photoneutron yield in linear accelerator with different collimation systems by Geant4 and MCNPX simulation codes.

    PubMed

    Kim, Yoon Sang; Khazaei, Zeinab; Ko, Junho; Afarideh, Hossein; Ghergherehchi, Mitra

    2016-04-07

    At present, the bremsstrahlung photon beams produced by linear accelerators are the most commonly employed method of radiotherapy for tumor treatments. A photoneutron source based on three different energies (6, 10 and 15 MeV) of a linac electron beam was designed by means of Geant4 and Monte Carlo N-Particle eXtended (MCNPX) simulation codes. To obtain maximum neutron yield, two arrangements for the photo neutron convertor were studied: (a) without a collimator, and (b) placement of the convertor after the collimator. The maximum photon intensities in tungsten were 0.73, 1.24 and 2.07 photon/e at 6, 10 and 15 MeV, respectively. There was no considerable increase in the photon fluence spectra from 6 to 15 MeV at the optimum thickness between 0.8 mm and 2 mm of tungsten. The optimum dimensions of the collimator were determined to be a length of 140 mm with an aperture of 5 mm  ×  70 mm for iron in a slit shape. According to the neutron yield, the best thickness obtained for the studied materials was 30 mm. The number of neutrons generated in BeO achieved the maximum value at 6 MeV, unlike that in Be, where the highest number of neutrons was observed at 15 MeV. Statistical uncertainty in all simulations was less than 0.3% and 0.05% for MCNPX and the standard electromagnetic (EM) physics packages of Geant4, respectively. Differences among spectra in various regions are due to various cross-section and stopping power data and different simulations of the physics processes.

  5. The GEANT4 toolkit capability in the hadron therapy field: simulation of a transport beam line

    NASA Astrophysics Data System (ADS)

    Cirrone, G. A. P.; Cuttone, G.; Di Rosa, F.; Raffaele, L.; Russo, G.; Guatelli, S.; Pia, M. G.

    2006-01-01

    At Laboratori Nazionali del Sud of the Instituto Nazionale di Fisica Nucleare of Catania (Sicily, Italy), the first Italian hadron therapy facility named CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) has been realized. Inside CATANA 62 MeV proton beams, accelerated by a superconducting cyclotron, are used for the radiotherapeutic treatments of some types of ocular tumours. Therapy with hadron beams still represents a pioneer technique, and only a few centers worldwide can provide this advanced specialized cancer treatment. On the basis of the experience so far gained, and considering the future hadron-therapy facilities to be developed (Rinecker, Munich Germany, Heidelberg/GSI, Darmstadt, Germany, PSI Villigen, Switzerland, CNAO, Pavia, Italy, Centro di Adroterapia, Catania, Italy) we decided to develop a Monte Carlo application based on the GEANT4 toolkit, for the design, the realization and the optimization of a proton-therapy beam line. Another feature of our project is to provide a general tool able to study the interactions of hadrons with the human tissue and to test the analytical-based treatment planning systems actually used in the routine practice. All the typical elements of a hadron-therapy line, such as diffusers, range shifters, collimators and detectors were modelled. In particular, we simulated the Markus type ionization chamber and a Gaf Chromic film as dosimeters to reconstruct the depth (Bragg peak and Spread Out Bragg Peak) and lateral dose distributions, respectively. We validated our simulated detectors comparing the results with the experimental data available in our facility.

  6. Optimization of {sup 6}LiF:ZnS(Ag) Scintillator Light Yield Using Geant4

    SciTech Connect

    Yehuda-Zada, Y.; Pritchard, K.; Ziegler, J.B.; Cooksey, C.; Siebein, K.; Jackson, M.; Hurlbut, C.; Kadmon, Y.; Cohen, Y.; Maliszewskyj, N.C.; Ibberson, R.M.; Majkrzak, C.F.; Orion, Y.; Osovizky, A.

    2015-07-01

    Neutrons provide an effective tool to probe materials structure. Neutron diffraction is a method to determine the atomic and magnetic structure of a material based on neutron scattering. By this method a collimated incident beam of thermal neutrons heat the examined sample and based on the obtained diffraction pattern information on the structure of the material is provided. Research for developing a novel cold neutron detector for Chromatic Analysis Neutron Diffractometer Or Reflectometer (CANDOR) is underway at the NIST center for neutron research. The system unique design is aimed to provide over ten times fold faster analysis of materials than conventional system. In order to achieve the fast analysis a large number of neutron detectors is required. A key design constraint for this detector is the thickness of the neutron sensitive element. This is met using {sup 6}LiF:ZnS(Ag) scintillation material with embedded wavelength shifting (WLS) fibers conducting scintillation light to silicon photomultiplier photo-sensors. The detector sensitivity is determined by both the neutron capture probability ({sup 6}Li density) and the detectable light output produced by the ZnS(Ag) ionization, the latter of which is hindered by the fluorescence absorption of the scintillation light by the ZnS. Tradeoffs between the neutron capture probability, stimulated light production and light attenuation for determining the optimal stoichiometry of the {sup 6}LiF and ZnS(Ag) as well as the volume ratio of scintillator and fiber. Simulations performed using the GEANT4 Monte Carlo package were made in order to optimize the detector design. GEANT4 enables the investigation of the neutron interaction with the detector, the ionization process and the light transfer process following the nuclear process. The series of conversions required for this detector were modelled: - A cold neutron enters the sensor and is captured by {sup 6}Li in the scintillator mixture ({sup 6}Li (n,α) {sup 3}H

  7. The radiation environment on the surface of Mars - Numerical calculations of the galactic component with GEANT4/PLANETOCOSMICS

    NASA Astrophysics Data System (ADS)

    Matthiä, Daniel; Berger, Thomas

    2017-08-01

    Galactic cosmic radiation and secondary particles produced in the interaction with the atmosphere lead to a complex radiation field on the Martian surface. A workshop (;1st Mars Space Radiation Modeling Workshop;) organized by the MSL-RAD science team was held in June 2016 in Boulder with the goal to compare models capable to predict this radiation field with each other and measurements from the RAD instrument onboard the curiosity rover taken between November 15, 2015 and January 15, 2016. In this work the results of PLANETOCOSMICS/GEANT4 contributed to the workshop are presented. Calculated secondary particle spectra on the Martian surface are investigated and the radiation field's directionality of the different particles in dependence on the energy is discussed. Omnidirectional particle fluxes are used in combination with fluence to dose conversion factors to calculate absorbed dose rates and dose equivalent rates in a slab of tissue.

  8. An investigation on the radiation sensitivity of DNA conformations to 60Co gamma rays by using Geant4 toolkit

    NASA Astrophysics Data System (ADS)

    Semsarha, F.; Goliaei, B.; Raisali, G.; Khalafi, H.; Mirzakhanian, L.

    2014-03-01

    To investigate the impact of conformational properties of genetic material of living cells on radiation-induced DNA damage, single strand breaks (SSB), double strand breaks (DSB) and some microdosimetric quantities of A, B and Z-DNA conformations caused by 60Co gamma rays, have been calculated. Based on a previous B-DNA geometrical model, models of A and Z forms have been developed. Simple 34 base pairs segments of each model repeated in high number and secondary electron spectrum of 60Co gamma rays have been simulated in a volume of a typical animal cell nucleus. All simulations in this study have been performed by using the Geant4 (GEometry ANd Tracking 4)-DNA extension of the Geant4 toolkit. The results showed that, B-DNA has the lowest yield of simple strand breaks with 2.23 × 10-10 Gy-1 Da-1 and 1.0 × 10-11 Gy-1 Da-1 for the SSB and DSB damage yield, respectively. The A-DNA has the highest SSB yield with 3.59 × 10-10 Gy-1 Da-1 and the Z-DNA has the highest DSB yields with 1.8 × 10-11 Gy-1 Da-1. It has been concluded that there is a direct correlation between the hit probability, mean specific imparted energy and SSB yield in each model of DNA. Moreover, there is a direct correlation between the DSB yield and both the mean lineal energy and topological characteristics of each model.

  9. Comparison of Geant4-DNA simulation of S-values with other Monte Carlo codes

    NASA Astrophysics Data System (ADS)

    André, T.; Morini, F.; Karamitros, M.; Delorme, R.; Le Loirec, C.; Campos, L.; Champion, C.; Groetz, J.-E.; Fromm, M.; Bordage, M.-C.; Perrot, Y.; Barberet, Ph.; Bernal, M. A.; Brown, J. M. C.; Deleuze, M. S.; Francis, Z.; Ivanchenko, V.; Mascialino, B.; Zacharatou, C.; Bardiès, M.; Incerti, S.

    2014-01-01

    Monte Carlo simulations of S-values have been carried out with the Geant4-DNA extension of the Geant4 toolkit. The S-values have been simulated for monoenergetic electrons with energies ranging from 0.1 keV up to 20 keV, in liquid water spheres (for four radii, chosen between 10 nm and 1 μm), and for electrons emitted by five isotopes of iodine (131, 132, 133, 134 and 135), in liquid water spheres of varying radius (from 15 μm up to 250 μm). The results have been compared to those obtained from other Monte Carlo codes and from other published data. The use of the Kolmogorov-Smirnov test has allowed confirming the statistical compatibility of all simulation results.

  10. Modification of source contribution in PALS by simulation using Geant4 code

    NASA Astrophysics Data System (ADS)

    Ning, Xia; Cao, Xingzhong; Li, Chong; Li, Demin; Zhang, Peng; Gong, Yihao; Xia, Rui; Wang, Baoyi; Wei, Long

    2017-04-01

    The contribution of positron source for the results of a positron annihilation lifetime spectrum (PALS) is simulated using Geant4 code. The geometrical structure of PALS measurement system is a sandwich structure: the 22Na radiation source is encapsulated by Kapton films, and the specimens are attached on the outside of the films. The probabilities of a positron being annihilated in the films, annihilated in the targets, and the effect of positrons reflected back from the specimen surface, are simulated. The probability of a positron annihilated in the film is related to the species of targets and the source film thickness. The simulation result is in reasonable agreement with the available experimental data. Thus, modification of the source contribution calculated by Geant4 is viable, and it beneficial for the analysis of the results of PALS.

  11. In-flight second order correction of PAMELA calorimeter characteristics (for simulation in Geant4)

    NASA Astrophysics Data System (ADS)

    Dunaeva, O. A.; Alekseev, V. V.; Bogomolov, Yu V.; Lukyanov, A. D.; Malakhov, V. V.; Mayorov, A. G.; Rodenko, S. A.

    2017-01-01

    Simulation of the PAMELA spectrometer characteristics is performed with the special program accepted by the PAMELA collaboration based on Geant4 package, which needs a detailed information about geometry, materials etc. of scientific equipment. This data is taken from manufactures or obtained from different ground-based tests including accelerators. We propose a method of in-flight verification of calorimeter characteristics. To calculate them we select relativistic protons passing through all the spectrometer without interactions. We obtain correction values from a comparison of experimental data and simulation in assumption that electromagnetic processes are performed in Geant4 with high precision. As a result, characteristics of silicon detectors (the sensitive part) are verified. Correction factor is 2.0 ± 0.3% with respect to original value.

  12. Geant4 simulation of clinical proton and carbon ion beams for the treatment of ocular melanomas with the full 3-D pencil beam scanning system

    SciTech Connect

    Farina, Edoardo; Riccardi, Cristina; Rimoldi, Adele; Tamborini, Aurora; Piersimoni, Pierluigi; Ciocca, Mario

    2015-07-01

    This work investigates the possibility to use carbon ion beams delivered with active scanning modality, for the treatment of ocular melanomas at the Centro Nazionale di Adroterapia Oncologica (CNAO) in Pavia. The radiotherapy with carbon ions offers many advantages with respect to the radiotherapy with protons or photons, such as a higher relative radio-biological effectiveness (RBE) and a dose release better localized to the tumor. The Monte Carlo (MC) Geant4 10.00 patch-03 toolkit is used to reproduce the complete CNAO extraction beam line, including all the active and passive components characterizing it. The simulation of proton and carbon ion beams and radiation scanned field is validated against CNAO experimental data. For the irradiation study of the ocular melanoma an eye-detector, representing a model of a human eye, is implemented in the simulation. Each element of the eye is reproduced with its chemical and physical properties. Inside the eye-detector a realistic tumor volume is placed and used as the irradiation target. A comparison between protons and carbon ions eye irradiations allows to study possible treatment benefits if carbon ions are used instead of protons. (authors)

  13. Geant4 simulation of a filtered X-ray source for radiation damage studies

    NASA Astrophysics Data System (ADS)

    Guthoff, M.; Brovchenko, O.; de Boer, W.; Dierlamm, A.; Müller, T.; Ritter, A.; Schmanau, M.; Simonis, H.-J.

    2012-05-01

    Geant4 low energy extensions have been used to simulate the X-ray spectra of industrial X-ray tubes with filters for removing the uncertain low energy part of the spectrum in a controlled way. The results are compared with precisely measured X-ray spectra using a silicon drift detector. Furthermore, this paper shows how the different dose rates in silicon and silicon dioxide layers of an electronic device can be deduced from the simulations.

  14. NEUTRON GENERATOR FACILITY AT SFU: GEANT4 DOSE RATE PREDICTION AND VERIFICATION.

    PubMed

    Williams, J; Chester, A; Domingo, T; Rizwan, U; Starosta, K; Voss, P

    2016-11-01

    Detailed dose rate maps for a neutron generator facility at Simon Fraser University were produced via the GEANT4 Monte Carlo framework. Predicted neutron dose rates throughout the facility were compared with radiation survey measurements made during the facility commissioning process. When accounting for thermal neutrons, the prediction and measurement agree within a factor of 2 or better in most survey locations, and within 10 % inside the vault housing the neutron generator.

  15. Comparisons of Electron and Muon Signals in the Atlas Liquid Argon Calorimeters with GEANT4 Simulations

    NASA Astrophysics Data System (ADS)

    Benchekroun, D.; Karpetian, G.; Mazini, R.; Kiryunin, A.; Salihagic, D.; Strizenec, P.; Kish, J.; Kordas, K.; Parrour, G.; Leltchouk, M.; Negroni, S.; Seligman, W.; Loch, P.; Soukharev, A.

    2002-01-01

    Signals from electrons and muons taken at testbeams with different modules of the ATLAS Liquid Argon Calorimeter have been compared to corresponding simulations using the GEANT4 toolkit. These simulations have also been compared in some detail with GEANT3 based predictions. Results for signal linearity, energy resolution, and shower shapes all generally indicate a good agreement between experiment and the two simulation packages, typically at the level of a few percent.

  16. Calculation of self-shielding factor for neutron activation experiments using GEANT4 and MCNP

    NASA Astrophysics Data System (ADS)

    Romero-Barrientos, Jaime; Molina, F.; Aguilera, Pablo; Arellano, H. F.

    2016-07-01

    The neutron self-shielding factor G as a function of the neutron energy was obtained for 14 pure metallic samples in 1000 isolethargic energy bins from 1.10-5eV to 2.107eV using Monte Carlo simulations in GEANT4 and MCNP6. The comparison of these two Monte Carlo codes shows small differences in the final self-shielding factor mostly due to the different cross section databases that each program uses.

  17. GMC: a GPU implementation of a Monte Carlo dose calculation based on Geant4.

    PubMed

    Jahnke, Lennart; Fleckenstein, Jens; Wenz, Frederik; Hesser, Jürgen

    2012-03-07

    We present a GPU implementation called GMC (GPU Monte Carlo) of the low energy (<100 GeV) electromagnetic part of the Geant4 Monte Carlo code using the NVIDIA® CUDA programming interface. The classes for electron and photon interactions as well as a new parallel particle transport engine were implemented. The way a particle is processed is not in a history by history manner but rather by an interaction by interaction method. Every history is divided into steps that are then calculated in parallel by different kernels. The geometry package is currently limited to voxelized geometries. A modified parallel Mersenne twister was used to generate random numbers and a random number repetition method on the GPU was introduced. All phantom results showed a very good agreement between GPU and CPU simulation with gamma indices of >97.5% for a 2%/2 mm gamma criteria. The mean acceleration on one GTX 580 for all cases compared to Geant4 on one CPU core was 4860. The mean number of histories per millisecond on the GPU for all cases was 658 leading to a total simulation time for one intensity-modulated radiation therapy dose distribution of 349 s. In conclusion, Geant4-based Monte Carlo dose calculations were significantly accelerated on the GPU.

  18. Comparison of dose distributions for Hounsfield number conversion methods in GEANT4

    NASA Astrophysics Data System (ADS)

    Kim, Hyung Dong; Kim, Byung Yong; Kim, Eng Chan; Yun, Sang Mo; Kang, Jeong Ku; Kim, Sung Kyu

    2014-06-01

    The conversion of patient computed tomography (CT) data to voxel phantoms is essential for CT-based Monte Carlo (MC) dose calculations, and incorrect assignments of materials and mass densities can lead to large errors in dose distributions. We investigated the effects of mass density and material assignments on GEANT4-based photon dose calculations. Three material conversion methods and four density conversion methods were compared for a lung tumor case. The dose calculations for 6-MV photon beams with a field size of 10 × 10 cm2 were performed using a 0.5 × 0.5 × 0.5 cm3 voxel with 1.2 × 109 histories. The material conversion methods led to different material assignment percentages in converted voxel regions. The GEANT4 example and the modified Schneider material conversion methods showed large local dose differences relative to the BEAMnrc default method for lung and other tissues. For mass density conversion methods when only water was used, our results showed only slight dose differences. Gaussian-like distributions, with mean values close to zero, were obtained when the reference method was compared with the other methods. The maximum dose difference of ˜2% indicated that the dose distributions agreed relatively well. Material assignment methods probably have more significant impacts on dose distributions than mass density assignment methods. The study confirms that material assignment methods cause significant dose differences in GEANT4-based photon dose calculations.

  19. Geant4 simulation for a study of a possible use of carbon ions pencil beam for the treatment of ocular melanomas with the active scanning system at CNAO Centre

    SciTech Connect

    Farina, E.; Piersimoni, P.; Riccardi, C.; Rimoldi, A.; Tamborini, A.; Ciocca, M.

    2015-07-01

    The aim of this work is to validate the Geant4 application reproducing the CNAO (National Centre for Oncological Hadrontherapy) beamline and to study of a possible use of carbon ion pencil beams for the treatment of ocular melanomas at the CNAO Centre. The promising aspect of carbon ions radiotherapy for the treatment of this disease lies in its superior relative radiobiological effectiveness (RBE). The Monte Carlo Geant4 toolkit is used to simulate the complete CNAO extraction beamline, with the active and passive components along it. A human eye modeled detector, including a realistic target tumor volume, is used as target. Cross check with previous studies at CNAO using protons allows comparisons on possible benefits on using such a technique with respect to proton beams. Before the eye-detector irradiation a validation of the Geant4 simulation with CNAO experimental data is carried out with both carbon ions and protons. Important beam parameters such as the transverse FWHM and scanned radiation field 's uniformity are tested within the simulation and compared with experimental measurements at CNAO Centre. The physical processes involved in secondary particles generation by carbon ions and protons in the eye-detector are reproduced to take into account the additional dose to the primary beam given to irradiated eye's tissues. A study of beam shaping is carried out to produce a uniform 3D dose distribution (shaped on the tumor) by the use of a spread out Bragg peak. The eye-detector is then irradiated through a two dimensional transverse beam scan at different depths. In the use case the eye-detector is rotated of an angle of 40 deg. in the vertical direction, in order to mis-align the tumor from healthy tissues in front of it. The treatment uniformity on the tumor in the eye-detector is tested. For a more quantitative description of the deposited dose in the eye-detector and for the evaluation of the ratio between the dose deposited in the tumor and the other

  20. MaGe-a Geant4-Based Monte Carlo Application Framework for Low-Background Germanium Experiments

    SciTech Connect

    Boswell, Melissa; Chan, Yuen-Dat; Detwiler, Jason A.; Finnerty, Padraic; Henning, Reyco; Gehman, Victor M.; Johnson, Rob A.; Jordan, David V.; Kazkaz, Kareem; Knapp, Markus; Kroninger, Kevin; Lenz, Daniel; Leviner, Lance; Liu, Jing; Liu, Xiang; MacMullin, Sean; Marino, Michael G.; Mokhtarani, Akbar; Pandola, Luciano; Schubert, Alexis G.; Schubert, Jens; Tomei, Claudia; Volynets, Oleksandr

    2011-06-01

    We describe a physics simulation software framework, MAGE, that is based on the GEANT4 simulation toolkit. MAGE is used to simulate the response of ultra-low radioactive background radiation detectors to ionizing radiation, specifically the MAJ ORANA and GE RDA neutrinoless double-beta decay experiments. MAJ ORANA and GERDA use high-purity germanium technology to search for the neutrinoless double-beta decay of the 76 Ge isotope, and MAGE is jointly developed between these two collaborations. The MAGE framework contains simulated geometries of common objects, prototypes, test stands, and the actual experiments. It also implements customized event generators, GE ANT 4 physics lists, and output formats. All of these features are available as class libraries that are typically compiled into a single executable. The user selects the particular experimental setup implementation at run-time via macros. The combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data and experiment, and simplifies the addition of new detectors to be simulated. This paper focuses on the software framework, custom event generators, and physics list.

  1. Application of Geant4 simulation for analysis of soil carbon inelastic neutron scattering measurements.

    PubMed

    Yakubova, Galina; Kavetskiy, Aleksandr; Prior, Stephen A; Torbert, H Allen

    2016-07-01

    Inelastic neutron scattering (INS) was applied to determine soil carbon content. Due to non-uniform soil carbon depth distribution, the correlation between INS signals with some soil carbon content parameter is not obvious; however, a proportionality between INS signals and average carbon weight percent in ~10cm layer for any carbon depth profile is demonstrated using Monte-Carlo simulation (Geant4). Comparison of INS and dry combustion measurements confirms this conclusion. Thus, INS measurements give the value of this soil carbon parameter.

  2. Study of silicon+6LiF thermal neutron detectors: GEANT4 simulations versus real data

    NASA Astrophysics Data System (ADS)

    Meo, S. Lo; Cosentino, L.; Mazzone, A.; Bartolomei, P.; Finocchiaro, P.

    2017-09-01

    Research and development on alternative thermal neutron detection technologies and methods are nowadays needed as a possible replacement of 3He-based ones. Commercial solid state silicon detectors, coupled with neutron converter layers containing 6Li, have been proved to represent a viable solution for several applications as present in the literature. In order to better understand the detailed operation and the response and efficiency of such detectors, a series of dedicated GEANT4 simulations were performed and compared with real data collected in a few different configurations. The results show an excellent agreement between data and simulations, indicating that the behavior of the detector is fully understood.

  3. Geant4 simulation of optical photon transport in scintillator tile with direct readout by silicon photomultiplier

    NASA Astrophysics Data System (ADS)

    Korpachev, S.; Chadeeva, M.

    2017-01-01

    The direct coupling of silicon photomultiplier to the scintillator tile is considered to be the main option for active elements of the highly granular hadron calorimeter developed for future linear collider experiments. In this study, the response of the scintillator-SiPM system to minimum ionising particles was simulated using the optical photon transport functionality available in the Geant4 package. The uniformity of response for both flat tile and tile with dimple was estimated from the simulations and compared to the experimental results obtained in the previous studies.

  4. Calculation of self–shielding factor for neutron activation experiments using GEANT4 and MCNP

    SciTech Connect

    Romero–Barrientos, Jaime; Molina, F.; Aguilera, Pablo; Arellano, H. F.

    2016-07-07

    The neutron self–shielding factor G as a function of the neutron energy was obtained for 14 pure metallic samples in 1000 isolethargic energy bins from 1·10{sup −5}eV to 2·10{sup 7}eV using Monte Carlo simulations in GEANT4 and MCNP6. The comparison of these two Monte Carlo codes shows small differences in the final self–shielding factor mostly due to the different cross section databases that each program uses.

  5. Summing-coincidence corrections with Geant4 in routine measurements by γ spectrometry of environmental samples.

    PubMed

    Quintana, B; Montes, C

    2014-05-01

    In this work, we describe a method to quantitatively evaluate true-coincidence-summing effects by making use of the Geant4 toolkit, which incorporates an emulation of the radionuclide disintegration scheme. To check the capabilities of the method, we firstly validated the simulated corrections using the ones obtained experimentally for radionuclides such as (60)Co, (152)Eu and (133)Ba. Secondly, we evaluated the effect of summing corrections of some radionuclides included in two intercomparison exercises to conclude that the results were improved when utilising the method described here. © 2013 Published by Elsevier Ltd.

  6. GEANT4 Hadron Monitor Simulation Studies for the Long-Baseline Neutrino Facility

    NASA Astrophysics Data System (ADS)

    Watson, Timothy; Bashyal, Amit; Yu, Jaehoon; Long Baseline Neutrino Facility Collaboration

    2015-04-01

    The hadron monitor to be incorporated into the beamline of the Long-Baseline Neutrino Facility at Fermilab is a crucial tool for alignment purposes as well as the correct functionality of the beam. Designing such a hadron monitor requires careful consideration of the challenges presented. The high-radiation environment from the considerably higher proton beam power expected for LBNF at the monitor location coupled with the need for relatively higher spatial resolution from the monitor will require an innovative new detector technology and design. To this end, computer simulations are a useful tool. Presented here are the results of hadron monitor design studies simulated using GEANT4.

  7. The reduction techniques of the particle background for the ATHENA X-IFU instrument at L2 orbit: Geant4 and the CryoAC

    NASA Astrophysics Data System (ADS)

    Macculi, Claudio, Piro, L.; Gatti, F.; Lotti, S.; Argan, A.; Laurenza, M.; D'Andrea, M.; Torrioli, G.; Biasotti, M.; Corsini, D.; Orlando, A.; Mineo, T.; D'Ai, A.; Molendi, S.; Gastaldello, F.; Bulgarelli, A.; Fioretti, V.; Jacquey, C.; Laurent, P.

    2015-09-01

    We present the particles background reduction techniques aimed at increasing the X-IFU sensitivity which is reduced by primary protons of both solar and Cosmic Rays origin, and secondary electrons. The adopted solutions involve Monte Carlo simulation by both Geant4 toolkit related to the "expected" background at L2 orbit through the payload mass model and the ray tracing technique to evaluate the soft protons components focussed by the optics to the main detector, and the development of an active Cryogenic AntiCoincidence detector and a passive electron shielding to meet the scientific requirements.

  8. Geant4-based Simulation Study of PEP-II Beam Backgrounds in the BABAR Detector at the SLAC B-Factory

    SciTech Connect

    Lockman, W.S.; Kozanecki, W.; Campbell, B.; Robertson, S.H.; Bondioli, M.; Calderini, G.; Barlow, N.; Edgar, C.L.; Aston, D.; Bower, G.; Cristinziani, M.; Fieguth, T.; Wright, D.H.; Petersen, B.A.; Blount, N.L.; Strom, D.; /Oregon U.

    2005-06-07

    To improve the understanding of accelerator-induced backgrounds at the SLAC B-Factory, we simulate lost particle backgrounds in the BABAR detector originating from beam-gas interactions and radiative Bhabha scatters. We have extended the GEANT4-based BABAR detector simulation to include beam-line components and magnetic fields up to 8.5 m away from the interaction point. We describe the simulation model and then compare preliminary predicted background levels with measurements from dedicated single- and colliding-beam experiments.

  9. Geant4 simulation of the Elekta XVI kV CBCT unit for accurate description of potential late toxicity effects of image-guided radiotherapy.

    PubMed

    Brochu, F M; Burnet, N G; Jena, R; Plaistow, R; Parker, M A; Thomas, S J

    2014-12-21

    This paper describes the modelisation of the Elekta XVI Cone Beam Computed Tomography (CBCT) machine components with Geant4 and its validation against calibration data taken for two commonly used machine setups. Preliminary dose maps of simulated CBCTs coming from this modelisation work are presented. This study is the first step of a research project, GHOST, aiming to improve the understanding of late toxicity risk in external beam radiotherapy patients by simulating dose depositions integrated from different sources (imaging, treatment beam) over the entire treatment plan. The second cancer risk will then be derived from different models relating irradiation dose and second cancer risk.

  10. Geant4 simulation of the Elekta XVI kV CBCT unit for accurate description of potential late toxicity effects of image-guided radiotherapy

    NASA Astrophysics Data System (ADS)

    Brochu, F. M.; Burnet, N. G.; Jena, R.; Plaistow, R.; Parker, M. A.; Thomas, S. J.

    2014-12-01

    This paper describes the modelisation of the Elekta XVI Cone Beam Computed Tomography (CBCT) machine components with Geant4 and its validation against calibration data taken for two commonly used machine setups. Preliminary dose maps of simulated CBCTs coming from this modelisation work are presented. This study is the first step of a research project, GHOST, aiming to improve the understanding of late toxicity risk in external beam radiotherapy patients by simulating dose depositions integrated from different sources (imaging, treatment beam) over the entire treatment plan. The second cancer risk will then be derived from different models relating irradiation dose and second cancer risk.

  11. Geant4 studies of the CNAO facility system for hadrontherapy treatment of uveal melanomas

    NASA Astrophysics Data System (ADS)

    Rimoldi, A.; Piersimoni, P.; Pirola, M.; Riccardi, C.

    2014-06-01

    The Italian National Centre of Hadrontherapy for Cancer Treatment (CNAO -Centro Nazionale di Adroterapia Oncologica) in Pavia, Italy, has started the treatment of selected cancers with the first patients in late 2011. In the coming months at CNAO plans are to activate a new dedicated treatment line for irradiation of uveal melanomas using the available active beam scan. The beam characteristics and the experimental setup should be tuned in order to reach the necessary precision required for such treatments. Collaboration between CNAO foundation, University of Pavia and INFN has started in 2011 to study the feasibility of these specialised treatments by implementing a MC simulation of the transport beam line and comparing the obtained simulation results with measurements at CNAO. The goal is to optimise an eye-dedicated transport beam line and to find the best conditions for ocular melanoma irradiations. This paper describes the Geant4 toolkit simulation of the CNAO setup as well as a modelised human eye with a tumour inside. The Geant4 application could be also used to test possible treatment planning systems. Simulation results illustrate the possibility to adapt the CNAO standard transport beam line by optimising the position of the isocentre and the addition of some passive elements to better shape the beam for this dedicated study.

  12. Simulation of positron backscattering and implantation profiles using Geant4 code

    NASA Astrophysics Data System (ADS)

    Huang, Shi-Juan; Pan, Zi-Wen; Liu, Jian-Dang; Han, Rong-Dian; Ye, Bang-Jiao

    2015-10-01

    For the proper interpretation of the experimental data produced in slow positron beam technique, the positron implantation properties are studied carefully using the latest Geant4 code. The simulated backscattering coefficients, the implantation profiles, and the median implantation depths for mono-energetic positrons with energy range from 1 keV to 50 keV normally incident on different crystals are reported. Compared with the previous experimental results, our simulation backscattering coefficients are in reasonable agreement, and we think that the accuracy may be related to the structures of the host materials in the Geant4 code. Based on the reasonable simulated backscattering coefficients, the adjustable parameters of the implantation profiles which are dependent on materials and implantation energies are obtained. The most important point is that we calculate the positron backscattering coefficients and median implantation depths in amorphous polymers for the first time and our simulations are in fairly good agreement with the previous experimental results. Project supported by the National Natural Science Foundation of China (Grant Nos. 11175171 and 11105139).

  13. Azimuthal angular dependence study of the atmospheric muon charge ratio at sea level using Geant4

    NASA Astrophysics Data System (ADS)

    Arslan, Halil; Bektasoglu, Mehmet

    2012-05-01

    The azimuth dependence of the cosmic muon charge ratio at sea level was estimated using the Geant4 simulation package. Simulations were separately run at 12 azimuth angles ranging from 0° to 330° with 30° increment. Two hundred thousand proton and alpha particles were randomly distributed over the zenith angle range 30° < θ < 40° at each azimuth angle. The kinetic energy spectra of proton and helium nuclei were taken from the balloon-flight measurements. The atmospheric muon charge ratio was calculated at each azimuthal angle for low energy muons with a mean momentum around 0.5 GeV/c. The Geant4 simulation results have been compared with those of the CORSIKA simulation program and with the WILLI measurements. The simulation results reproduce well the measured east-west effect with a non-zero asymmetry AEW = 0.24. This asymmetry in the charge ratio decreases from 0.37 to 0.19 as the momentum increases from 0.22 to 0.70 GeV/c.

  14. GEANT4 simulation of the response of a liquid scintillation counter

    NASA Astrophysics Data System (ADS)

    Hurtado, S.

    2017-09-01

    Liquid Scintillation Counting (LSC) is widely used as a very efficient technique for radioactivity quantification. LSC is a powerful tool applied as much in low level environmental radioactivity monitoring, as in radionuclide metrology for the activity standardization of electron capture, pure-beta, and alpha nuclides. In order to quantify the sample activity, the number of scintillation photons are counted by one or several PMTs. However, the scintillation count rate varies with the detection efficiency. As an alternative to traditional methods for the calculation of detection efficiency, a Monte Carlo approach based on GEANT4 toolkit is presented for the simulation of light emission inside a Quantulus 1220 liquid scintillation counter with two PMT photomultipliers tubes working in sum-coincidence mode. To this end, the GEANT4 simulation handles a variety of processes at optical wavelengths including refraction and reflection at medium boundaries, Rayleigh scattering and bulk absorption, and additional processes which produce optical photons such as Cherenkov effect, transition radiation and scintillation, and includes a description of optical properties associated with each material constituting the detection system. The objective is to simulate the propagation of optical photons from their creation in the liquid scintillation cocktail to the production of photoelectrons in the PMTs. In this paper, we report in detail the results of the proposed simulation (detection efficiency, and additionally wall effect and absorption probabilities of gamma-rays) for different radionuclides such as 14C, 3H, 54Mn and 90Y, and its validation through the comparison with the experimental measurements.

  15. Efficient voxel navigation for proton therapy dose calculation in TOPAS and Geant4

    NASA Astrophysics Data System (ADS)

    Schümann, J.; Paganetti, H.; Shin, J.; Faddegon, B.; Perl, J.

    2012-06-01

    A key task within all Monte Carlo particle transport codes is ‘navigation’, the calculation to determine at each particle step what volume the particle may be leaving and what volume the particle may be entering. Navigation should be optimized to the specific geometry at hand. For patient dose calculation, this geometry generally involves voxelized computed tomography (CT) data. We investigated the efficiency of navigation algorithms on currently available voxel geometry parameterizations in the Monte Carlo simulation package Geant4: G4VPVParameterisation, G4VNestedParameterisation and G4PhantomParameterisation, the last with and without boundary skipping, a method where neighboring voxels with the same Hounsfield unit are combined into one larger voxel. A fourth parameterization approach (MGHParameterization), developed in-house before the latter two parameterizations became available in Geant4, was also included in this study. All simulations were performed using TOPAS, a tool for particle simulations layered on top of Geant4. Runtime comparisons were made on three distinct patient CT data sets: a head and neck, a liver and a prostate patient. We included an additional version of these three patients where all voxels, including the air voxels outside of the patient, were uniformly set to water in the runtime study. The G4VPVParameterisation offers two optimization options. One option has a 60-150 times slower simulation speed. The other is compatible in speed but requires 15-19 times more memory compared to the other parameterizations. We found the average CPU time used for the simulation relative to G4VNestedParameterisation to be 1.014 for G4PhantomParameterisation without boundary skipping and 1.015 for MGHParameterization. The average runtime ratio for G4PhantomParameterisation with and without boundary skipping for our heterogeneous data was equal to 0.97: 1. The calculated dose distributions agreed with the reference distribution for all but the G4

  16. Comparative studies on shielding properties of some steel alloys using Geant4, MCNP, WinXCOM and experimental results

    NASA Astrophysics Data System (ADS)

    Singh, Vishwanath P.; Medhat, M. E.; Shirmardi, S. P.

    2015-01-01

    The mass attenuation coefficients, μ/ρ and effective atomic numbers, Zeff of some carbon steel and stainless steel alloys have been calculated by using Geant4, MCNP simulation codes for different gamma ray energies, 279.1 keV, 661.6 keV, 662 keV, 1115.5 keV, 1173 keV and 1332 keV. The simulation results of Zeff using Geant4 and MCNP codes have been compared with possible available experimental results and theoretical WinXcom, and good agreement has been observed. The simulated μ/ρ and Zeff values using Geant4 and MCNP code signifies that both the simulation process can be followed to determine the gamma ray interaction properties of the alloys for energies wherever analogous experimental results may not be available. This kind of studies can be used for various applications such as for radiation dosimetry, medical and radiation shielding.

  17. Differing Lunar Regolith Hydrogen Distributions as a Possible Source of Variations in Proton Albedo: Geant4 Simulations

    NASA Astrophysics Data System (ADS)

    Looper, M. D.; Mazur, J. E.; Blake, J. B.; Schwadron, N.; Wilson, J. K.; Spence, H. E.; Case, A. W.; Kasper, J. C.; Townsend, L. W.

    2016-12-01

    Since entering lunar orbit in 2009, the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) has measured "albedo" protons coming upward from the moon after being produced by nuclear interactions of galactic cosmic rays (GCRs) in the regolith. Over the past seven years, we have measured variations in the yield of albedo protons as a function of their source locations on the moon and of local time at those locations. In our ongoing efforts to understand the causes of these variations, we have considered changes in the composition of in the lunar regolith struck by the GCRs, modeling the production of upward-going albedo using the Geant4 open-source radiation transport code. In this talk we will present the results of simulations of the albedo proton yield as we vary the amount and thickness of hydrogen (or hydrogen-bearing compounds) mixed with the regolith. The modeling predicts significant changes in yield with changing hydrogen concentrations within tens of centimeters of the lunar surface. Such changes in hydrogen concentrations in the upper regolith layer may contribute to observed diurnal changes in the proton albedo yield.

  18. Study of Cosmic Ray Muon Lateral Distribution with Geant4 Simulation

    NASA Astrophysics Data System (ADS)

    Sarajlic, Olesya; He, Xiaochun

    2016-09-01

    Cosmic ray radiation has galactic origin and consists primarily of protons and a small percentage of heavier nuclei. The primary cosmic ray particles interact with the molecules in the atmosphere and produce showers of secondary particles at about 15 km altitude. In recent years, with the advancement in particle detection technology, there is a growing interest of exploring the applications of cosmic ray muons ranging from Homeland Security, correlation study with the atmospheric weather, etc. A Geant4-based cosmic ray shower simulation is developed to study secondary cosmic ray particle showers in the full range of the Earth's atmosphere. In this talk, the diurnal and latitudinal variations of muon lateral distributions will be presented.

  19. Signal pulse emulation for scintillation detectors using Geant4 Monte Carlo with light tracking simulation

    SciTech Connect

    Ogawara, R.; Ishikawa, M.

    2016-07-15

    The anode pulse of a photomultiplier tube (PMT) coupled with a scintillator is used for pulse shape discrimination (PSD) analysis. We have developed a novel emulation technique for the PMT anode pulse based on optical photon transport and a PMT response function. The photon transport was calculated using Geant4 Monte Carlo code and the response function with a BC408 organic scintillator. The obtained percentage RMS value of the difference between the measured and simulated pulse with suitable scintillation properties using GSO:Ce (0.4, 1.0, 1.5 mol%), LaBr{sub 3}:Ce and BGO scintillators were 2.41%, 2.58%, 2.16%, 2.01%, and 3.32%, respectively. The proposed technique demonstrates high reproducibility of the measured pulse and can be applied to simulation studies of various radiation measurements.

  20. GEANT4 calibration of gamma spectrometry efficiency for measurements of airborne radioactivity on filter paper.

    PubMed

    Alrefae, Tareq

    2014-11-01

    A simple method of efficiency calibration for gamma spectrometry was performed. This method, which focused on measuring airborne radioactivity collected on filter paper, was based on Monte Carlo simulations using the toolkit GEANT4. Experimentally, the efficiency values of an HPGe detector were calculated for a multi-gamma disk source. These efficiency values were compared to their counterparts produced by a computer code that simulated experimental conditions. Such comparison revealed biases of 24, 10, 1, 3, 7, and 3% for the radionuclides (photon energies in keV) of Ce (166), Sn (392), Cs (662), Co (1,173), Co (1,333), and Y (1,836), respectively. The output of the simulation code was in acceptable agreement with the experimental findings, thus validating the proposed method.

  1. Geant4 simulation of the n_TOF-EAR2 neutron beam: Characteristics and prospects

    NASA Astrophysics Data System (ADS)

    Lerendegui-Marco, J.; Lo Meo, S.; Guerrero, C.; Cortés-Giraldo, M. A.; Massimi, C.; Quesada, J. M.; Barbagallo, M.; Colonna, N.; Mancusi, D.; Mingrone, F.; Sabaté-Gilarte, M.; Vannini, G.; Vlachoudis, V.

    2016-04-01

    The characteristics of the neutron beam at the new n_TOF-EAR2 facility have been simulated with the Geant4 code with the aim of providing useful data for both the analysis and planning of the upcoming measurements. The spatial and energy distributions of the neutrons, the resolution function and the in-beam γ-ray background have been studied in detail and their implications in the forthcoming experiments have been discussed. The results confirm that, with this new short (18.5m flight path) beam line, reaching an instantaneous neutron flux beyond 105n/μs/pulse in the keV region, n_TOF is one of the few facilities where challenging measurements can be performed, involving in particular short-lived radioisotopes.

  2. Geant4 calculations for space radiation shielding material Al2O3

    NASA Astrophysics Data System (ADS)

    Capali, Veli; Acar Yesil, Tolga; Kaya, Gokhan; Kaplan, Abdullah; Yavuz, Mustafa; Tilki, Tahir

    2015-07-01

    Aluminium Oxide, Al2O3 is the most widely used material in the engineering applications. It is significant aluminium metal, because of its hardness and as a refractory material owing to its high melting point. This material has several engineering applications in diverse fields such as, ballistic armour systems, wear components, electrical and electronic substrates, automotive parts, components for electric industry and aero-engine. As well, it is used as a dosimeter for radiation protection and therapy applications for its optically stimulated luminescence properties. In this study, stopping powers and penetrating distances have been calculated for the alpha, proton, electron and gamma particles in space radiation shielding material Al2O3 for incident energies 1 keV - 1 GeV using GEANT4 calculation code.

  3. Geant4 Predictions of Energy Spectra in Typical Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Sabra, M. S.; Barghouty, A. F.

    2014-01-01

    Accurate knowledge of energy spectra inside spacecraft is important for protecting astronauts as well as sensitive electronics from the harmful effects of space radiation. Such knowledge allows one to confidently map the radiation environment inside the vehicle. The purpose of this talk is to present preliminary calculations for energy spectra inside a spherical shell shielding and behind a slab in typical space radiation environment using the 3D Monte-Carlo transport code Geant4. We have simulated proton and iron isotropic sources and beams impinging on Aluminum and Gallium arsenide (GaAs) targets at energies of 0.2, 0.6, 1, and 10 GeV/u. If time permits, other radiation sources and beams (_, C, O) and targets (C, Si, Ge, water) will be presented. The results are compared to ground-based measurements where available.

  4. Comparison of MCNPX and Geant4 proton energy deposition predictions for clinical use

    PubMed Central

    Titt, U.; Bednarz, B.; Paganetti, H.

    2012-01-01

    Several different Monte Carlo codes are currently being used at proton therapy centers to improve upon dose predictions over standard methods using analytical or semi-empirical dose algorithms. There is a need to better ascertain the differences between proton dose predictions from different available Monte Carlo codes. In this investigation Geant4 and MCNPX, the two most-utilized Monte Carlo codes for proton therapy applications, were used to predict energy deposition distributions in a variety of geometries, comprising simple water phantoms, water phantoms with complex inserts and in a voxelized geometry based on clinical CT data. The gamma analysis was used to evaluate the differences of the predictions between the codes. The results show that in the all cases the agreement was better than clinical acceptance criteria. PMID:22996039

  5. Validation of GEANT4 simulations for 62,63Zn yield estimation in proton induced reactions of natural copper

    NASA Astrophysics Data System (ADS)

    Rostampour, Malihe; Sadeghi, Mahdi; Aboudzadeh, Mohammadreza; Hamidi, Saeid; Hosseini, Seyedeh Fatemeh

    2017-03-01

    A useful approach to optimize of radioisotope production is the use of Monte Carlo simulations prior to experimentation. In this paper, the GEANT4 code was employed to calculate the saturation yields of 62,63Zn from proton-induced reactions of natural copper, enriched 63Cu and 65Cu. In addition, the saturation yields of the investigated radio-nuclides were calculated using the stopping power from the SRIM-2013 and reported experimental data for cross sections. The simulated saturation yields were compared with experimental values. Good agreement between the experimental and corresponding simulated data demonstrated that GEANT4 provides a suitable tool for radionuclide simulation production using proton irradiation.

  6. Geant4-DNA simulation of DNA damage caused by direct and indirect radiation effects and comparison with biological data.

    NASA Astrophysics Data System (ADS)

    Villagrasa, Carmen; Meylan, Sylvain; Gonon, Geraldine; Gruel, Gaëtan; Giesen, Ulrich; Bueno, Marta; Rabus, Hans

    2017-09-01

    In this work we present results obtained in the frame of the BioQuaRT project. The objective of the study was the correlation between the number of radiation-induced double strand breaks (DSB) of the DNA molecule and the probability of detecting nuclear foci after targeted microbeam irradiation of cells with protons and alpha particles of different LET. The former were obtained by simulation with new methods integrated into Geant4-DNA that permit calculating the number of DSB in a DNA target model induced by direct and indirect radiation effects. A particular focus was laid in this work on evaluating the influence of different criteria applied to the simulated results for predicting the formation of a direct SSB. Indeed, these criteria have an important impact on the predicted number of DSB per particle track and its dependence with LET. Among the criteria tested in this work, the case that a direct radiation interaction leads to a strand break if the cumulative energy deposited in the backbone part of one nucleotide exceeds a threshold of 17.5 eV leads to the best agreement with the relative LET dependence of number of radiation induced foci. Further calculations and experimental data are nevertheless needed in order to fix the simulation parameters and to help interpreting the biological experimental data observed by immunofluorescence in terms of the DSB complexity.

  7. Angular and energy distribution for parent primaries of cosmic muons at the sea level using Geant4

    NASA Astrophysics Data System (ADS)

    Arslan, Halil; Bektasoglu, Mehmet

    2015-04-01

    The angular and energy distributions of the primary cosmic rays that are responsible for the muons reaching the sea level have been estimated using the Geant4 simulation package. The models used in the simulations were tested by comparing the simulation results for the differential muon flux with the BESS measurements performed in Lynn Lake, Canada. Then, direct relationship between the propagation directions of the muons and those of the responsible primary particles has been investigated. The median energies for the parent primaries of vertical muons reaching the sea level with the threshold energies (Eμ) in the range 0.5-300 GeV were obtained. Simulation results for the median primary energies, 15.5Eμ and 11.2Eμ for Eμ = 14 GeV and Eμ = 100 GeV, have been found to be in good agreement with the literature. Furthermore, median primary energies for the low energy muons with large zenith angle have been seen to be relatively higher than the ones for the muons with narrower angles.

  8. G4MoNA - A Geant4 Simulation for unbound nuclides detected with MoNA/LISA

    NASA Astrophysics Data System (ADS)

    Gueye, Paul; Freeman, Jessica; Frank, Nathan; MoNA Collaboration

    2017-01-01

    The MoNA Collaboration has conducted a plethora of experiments to study unbound nuclei near the neutron dripline using the invariant mass technique since 2005. These experiments used a variety of secondary beams from the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory. The experimental setup consists of a large gap superconducting Sweeper magnet for charged fragments separation and the MoNA/LISA neutron detector arrays for neutron detection. Recently, a multi-layered Si/Be segmented target consisting of three 700 mg/cm2 thick 9Be slabs and four 140 μ m Si detectors were added to the setup. This target improves the resolution of the reconstructed decay energy spectra of the unbound nuclides. The Geant4 Monte Carlo simulation toolkit was used to develop a complete realistic model of the setup including a new class to treat the decay of unbound nuclei, the Si/Be segmented target, the MoNA/LISA and the charged fragments detector systems. Comparison between simulated and experimental data will be presented. DoENNSA - DE-NA0000979.

  9. Efficiency transfer using the GEANT4 code of CERN for HPGe gamma spectrometry.

    PubMed

    Chagren, S; Ben Tekaya, M; Reguigui, N; Gharbi, F

    2016-01-01

    In this work we apply the GEANT4 code of CERN to calculate the peak efficiency in High Pure Germanium (HPGe) gamma spectrometry using three different procedures. The first is a direct calculation. The second corresponds to the usual case of efficiency transfer between two different configurations at constant emission energy assuming a reference point detection configuration and the third, a new procedure, consists on the transfer of the peak efficiency between two detection configurations emitting the gamma ray in different energies assuming a "virtual" reference point detection configuration. No pre-optimization of the detector geometrical characteristics was performed before the transfer to test the ability of the efficiency transfer to reduce the effect of the ignorance on their real magnitude on the quality of the transferred efficiency. The obtained and measured efficiencies were found in good agreement for the two investigated methods of efficiency transfer. The obtained agreement proves that Monte Carlo method and especially the GEANT4 code constitute an efficient tool to obtain accurate detection efficiency values. The second investigated efficiency transfer procedure is useful to calibrate the HPGe gamma detector for any emission energy value for a voluminous source using one point source detection efficiency emitting in a different energy as a reference efficiency. The calculations preformed in this work were applied to the measurement exercise of the EUROMET428 project. A measurement exercise where an evaluation of the full energy peak efficiencies in the energy range 60-2000 keV for a typical coaxial p-type HpGe detector and several types of source configuration: point sources located at various distances from the detector and a cylindrical box containing three matrices was performed.

  10. The effects of mapping CT images to Monte Carlo materials on GEANT4 proton simulation accuracy

    SciTech Connect

    Barnes, Samuel; McAuley, Grant; Slater, James; Wroe, Andrew

    2013-04-15

    Purpose: Monte Carlo simulations of radiation therapy require conversion from Hounsfield units (HU) in CT images to an exact tissue composition and density. The number of discrete densities (or density bins) used in this mapping affects the simulation accuracy, execution time, and memory usage in GEANT4 and other Monte Carlo code. The relationship between the number of density bins and CT noise was examined in general for all simulations that use HU conversion to density. Additionally, the effect of this on simulation accuracy was examined for proton radiation. Methods: Relative uncertainty from CT noise was compared with uncertainty from density binning to determine an upper limit on the number of density bins required in the presence of CT noise. Error propagation analysis was also performed on continuously slowing down approximation range calculations to determine the proton range uncertainty caused by density binning. These results were verified with Monte Carlo simulations. Results: In the presence of even modest CT noise (5 HU or 0.5%) 450 density bins were found to only cause a 5% increase in the density uncertainty (i.e., 95% of density uncertainty from CT noise, 5% from binning). Larger numbers of density bins are not required as CT noise will prevent increased density accuracy; this applies across all types of Monte Carlo simulations. Examining uncertainty in proton range, only 127 density bins are required for a proton range error of <0.1 mm in most tissue and <0.5 mm in low density tissue (e.g., lung). Conclusions: By considering CT noise and actual range uncertainty, the number of required density bins can be restricted to a very modest 127 depending on the application. Reducing the number of density bins provides large memory and execution time savings in GEANT4 and other Monte Carlo packages.

  11. A Geant4 simulation of the depth dose percentage in brain tumors treatments using protons and carbon ions

    NASA Astrophysics Data System (ADS)

    José A. Diaz, M.; Torres, D. A.

    2016-07-01

    The deposited energy and dose distribution of beams of protons and carbon over a head are simulated using the free tool package Geant4 and the data analysis package ROOT-C++. The present work shows a methodology to understand the microscopical process occurring in a session of hadron-therapy using advance simulation tools.

  12. A Geant4 simulation of the depth dose percentage in brain tumors treatments using protons and carbon ions

    SciTech Connect

    Diaz, José A. M. Torres, D. A.

    2016-07-07

    The deposited energy and dose distribution of beams of protons and carbon over a head are simulated using the free tool package Geant4 and the data analysis package ROOT-C++. The present work shows a methodology to understand the microscopical process occurring in a session of hadron-therapy using advance simulation tools.

  13. Sensitivity analysis for liver iron measurement through neutron stimulated emission computed tomography: a Monte Carlo study in GEANT4.

    PubMed

    Agasthya, G A; Harrawood, B C; Shah, J P; Kapadia, A J

    2012-01-07

    Neutron stimulated emission computed tomography (NSECT) is being developed as a non-invasive imaging modality to detect and quantify iron overload in the human liver. NSECT uses gamma photons emitted by the inelastic interaction between monochromatic fast neutrons and iron nuclei in the body to detect and quantify the disease. Previous simulated and physical experiments with phantoms have shown that NSECT has the potential to accurately diagnose iron overload with reasonable levels of radiation dose. In this work, we describe the results of a simulation study conducted to determine the sensitivity of the NSECT system for hepatic iron quantification in patients of different sizes. A GEANT4 simulation of the NSECT system was developed with a human liver and two torso sizes corresponding to small and large patients. The iron concentration in the liver ranged between 0.5 and 20 mg g(-1), corresponding to clinically reported iron levels in iron-overloaded patients. High-purity germanium gamma detectors were simulated to detect the emitted gamma spectra, which were background corrected using suitable water phantoms and analyzed to determine the minimum detectable level (MDL) of iron and the sensitivity of the NSECT system. These analyses indicate that for a small patient (torso major axis = 30 cm) the MDL is 0.5 mg g(-1) and sensitivity is ∼13 ± 2 Fe counts/mg/mSv and for a large patient (torso major axis = 40 cm) the values are 1 mg g(-1) and ∼5 ± 1 Fe counts/mg/mSv, respectively. The results demonstrate that the MDL for both patient sizes lies within the clinically significant range for human iron overload.

  14. Feasibility of using Geant4 Monte Carlo simulation for IMRT dose calculations for the Novalis Tx with a HD-120 multi-leaf collimator

    NASA Astrophysics Data System (ADS)

    Jung, Hyunuk; Shin, Jungsuk; Chung, Kwangzoo; Han, Youngyih; Kim, Jinsung; Choi, Doo Ho

    2015-05-01

    The aim of this study was to develop an independent dose verification system by using a Monte Carlo (MC) calculation method for intensity modulated radiation therapy (IMRT) conducted by using a Varian Novalis Tx (Varian Medical Systems, Palo Alto, CA, USA) equipped with a highdefinition multi-leaf collimator (HD-120 MLC). The Geant4 framework was used to implement a dose calculation system that accurately predicted the delivered dose. For this purpose, the Novalis Tx Linac head was modeled according to the specifications acquired from the manufacturer. Subsequently, MC simulations were performed by varying the mean energy, energy spread, and electron spot radius to determine optimum values of irradiation with 6-MV X-ray beams by using the Novalis Tx system. Computed percentage depth dose curves (PDDs) and lateral profiles were compared to the measurements obtained by using an ionization chamber (CC13). To validate the IMRT simulation by using the MC model we developed, we calculated a simple IMRT field and compared the result with the EBT3 film measurements in a water-equivalent solid phantom. Clinical cases, such as prostate cancer treatment plans, were then selected, and MC simulations were performed. The accuracy of the simulation was assessed against the EBT3 film measurements by using a gamma-index criterion. The optimal MC model parameters to specify the beam characteristics were a 6.8-MeV mean energy, a 0.5-MeV energy spread, and a 3-mm electron radius. The accuracy of these parameters was determined by comparison of MC simulations with measurements. The PDDs and the lateral profiles of the MC simulation deviated from the measurements by 1% and 2%, respectively, on average. The computed simple MLC fields agreed with the EBT3 measurements with a 95% passing rate with 3%/3-mm gamma-index criterion. Additionally, in applying our model to clinical IMRT plans, we found that the MC calculations and the EBT3 measurements agreed well with a passing rate of greater

  15. Monte Carlo simulation of ruthenium eye plaques with GEANT4: influence of multiple scattering algorithms, the spectrum and the geometry on depth dose profiles

    NASA Astrophysics Data System (ADS)

    Sommer, H.; Ebenau, M.; Spaan, B.; Eichmann, M.

    2017-03-01

    Previous studies show remarkable differences in the simulation of electron depth dose profiles of ruthenium eye plaques. We examined the influence of the scoring and simulation geometry, the source spectrum and the multiple scattering algorithm on the depth dose profile using GEANT4. The simulated absolute dose deposition agrees with absolute dose data from the manufacturer within the measurement uncertainty. Variations in the simulation geometry as well as the source spectrum have only a small influence on the depth dose profiles. However, the multiple scattering algorithms have the largest influence on the depth dose profiles. They deposit up to 20% less dose compared to the single scattering implementation. We recommend researchers who are interested in simulating low- to medium-energy electrons to examine their simulation under the influence of different multiple scattering settings. Since the simulation and scoring geometry as well as the exact physics settings are best described by the source code of the application, we made the code publicly available.

  16. WE-C-217BCD-11: Coupled Radiative and Optical Geant4 Simulation of MV EPIDs Based on Thick Pixelated Scintillating Crystals.

    PubMed

    Constantin, D; Sun, M; Abel, E; Star-Lack, J; Fahrig, R

    2012-06-01

    One way to greatly reduce the incidence of metal artifacts produced in kilovoltage (kV) CT images is by using megavoltage (MV) photons that penetrate high-Z objects, thus providing a measurable signal. For do se-efficient imaging, a high detective quantum efficiency (DQE) MV detector is desired. This study validates the coupled radiation and optical Geant4 simulation results against experimental data from various prototype pixelated scintillator MV detectors and determines the essential optical parameters which control the detector performance. Experimental data obtained with a 6MV radiation source from 8 different detectors was considered. The detectors used CsI, CdW and BGO as scintillating crystals and polystyrene septal wall material. Accurate Geant4 models of the detectors were implemented and coupled radiation and optical simulations were performed. The unknown optical properties of the models were determined by minimizing the difference between the modulation transfer functions (MTF) of the simulated data obtained with the slanted slit technique and the experimental MTFs. With the set of optical properties fixed, further simulation validation was performed against the experimental normalized noise power spectrum (NNPS(f)) and the experimental DQE(f) curves for each detector. All the simulations were performed on a computer cluster deployed on the Amazon EC2 platform. The optimal values for the free optical parameters are 10%, 95% and 90% for the top surface reflectivity, the crystal-sept a surface reflectivity, and the Lambertian component contribution to the reflected beam from the crystal-septa interface respectively. The absolute difference between experimental and simulated data was below 10% for all the data sets. To our knowledge this study is the first to present a full optical and radiative DQE(f) model using Geant4 that shows an excellent match with experimental data. The model indicates that improved performance can be obtained using more specular

  17. Benchmarking and validation of a Geant4-SHADOW Monte Carlo simulation for dose calculations in microbeam radiation therapy.

    PubMed

    Cornelius, Iwan; Guatelli, Susanna; Fournier, Pauline; Crosbie, Jeffrey C; Sanchez Del Rio, Manuel; Bräuer-Krisch, Elke; Rosenfeld, Anatoly; Lerch, Michael

    2014-05-01

    Microbeam radiation therapy (MRT) is a synchrotron-based radiotherapy modality that uses high-intensity beams of spatially fractionated radiation to treat tumours. The rapid evolution of MRT towards clinical trials demands accurate treatment planning systems (TPS), as well as independent tools for the verification of TPS calculated dose distributions in order to ensure patient safety and treatment efficacy. Monte Carlo computer simulation represents the most accurate method of dose calculation in patient geometries and is best suited for the purpose of TPS verification. A Monte Carlo model of the ID17 biomedical beamline at the European Synchrotron Radiation Facility has been developed, including recent modifications, using the Geant4 Monte Carlo toolkit interfaced with the SHADOW X-ray optics and ray-tracing libraries. The code was benchmarked by simulating dose profiles in water-equivalent phantoms subject to irradiation by broad-beam (without spatial fractionation) and microbeam (with spatial fractionation) fields, and comparing against those calculated with a previous model of the beamline developed using the PENELOPE code. Validation against additional experimental dose profiles in water-equivalent phantoms subject to broad-beam irradiation was also performed. Good agreement between codes was observed, with the exception of out-of-field doses and toward the field edge for larger field sizes. Microbeam results showed good agreement between both codes and experimental results within uncertainties. Results of the experimental validation showed agreement for different beamline configurations. The asymmetry in the out-of-field dose profiles due to polarization effects was also investigated, yielding important information for the treatment planning process in MRT. This work represents an important step in the development of a Monte Carlo-based independent verification tool for treatment planning in MRT.

  18. Simulating Neutron Interactions in the MoNA-LISA/Sweeper Setup with Geant4

    NASA Astrophysics Data System (ADS)

    McArthur, Magdalene

    2012-10-01

    The sweeper magnet is a superconducting dipole designed to bend charged particles of 4 Tm rigidity 43 degrees at a radius of approximately one meter. In a typical experiment neutron-unbound states are populated in a reaction in front of the magnet and emitted neutrons are subsequently detected with the high-efficiency position sensitive neutron detector arrays, MoNA and LISA. Before the neutrons interact in MoNA or LISA, they have to pass through the walls of the sweeper magnet chamber. A Monte Carlo simulation was written using Geant 4 which included MoNA and LISA, as well as the geometry of the sweeper magnet and the chamber. In a recent experiment LISA was positioned at large angles were the neutrons passed through the sidewalls of the chamber. The impact of the sidewalls on the neutron spectra was explored for neutrons from the decay of 12Li -> 11Li + n produced from 50 MeV/u 14B beams on a beryllium target.

  19. VIDA: a voxel-based dosimetry method for targeted radionuclide therapy using Geant4.

    PubMed

    Kost, Susan D; Dewaraja, Yuni K; Abramson, Richard G; Stabin, Michael G

    2015-02-01

    We have developed the Voxel-Based Internal Dosimetry Application (VIDA) to provide patient-specific dosimetry in targeted radionuclide therapy performing Monte Carlo simulations of radiation transport with the Geant4 toolkit. The code generates voxel-level dose rate maps using anatomical and physiological data taken from individual patients. Voxel level dose rate curves are then fit and integrated to yield a spatial map of radiation absorbed dose. In this article, we present validation studies using established dosimetry results, including self-dose factors (DFs) from the OLINDA/EXM program for uniform activity in unit density spheres and organ self- and cross-organ DFs in the Radiation Dose Assessment Resource (RADAR) reference adult phantom. The comparison with reference data demonstrated agreement within 5% for self-DFs to spheres and reference phantom source organs for four common radionuclides used in targeted therapy ((131)I, (90)Y, (111)In, (177)Lu). Agreement within 9% was achieved for cross-organ DFs. We also present dose estimates to normal tissues and tumors from studies of two non-Hodgkin Lymphoma patients treated by (131)I radioimmunotherapy, with comparison to results generated independently with another dosimetry code. A relative difference of 12% or less was found between methods for mean absorbed tumor doses accounting for tumor regression.

  20. GEANT4 simulation of NSECT for detection of iron overload in the liver

    NASA Astrophysics Data System (ADS)

    Kapadia, Anuj J.; Harrawood, Brian P.; Tourassi, Georgia D.

    2008-03-01

    Neutron stimulated emission computed tomography (NSECT) is being proposed as a non-invasive technique to diagnose iron overload in humans. It uses inelastic scatter interactions between incident neutrons and iron nuclei to stimulate gamma-ray emission from iron. Tomographic detection of the emitted gamma-rays yields information about the concentration and spatial distribution of iron in the liver. Early proof-of-concept experiments have shown that NSECT has the potential to quantify clinical quantities of liver iron overload through single-position spectroscopy. However, a tomography application for patient diagnosis has never been tested. This work uses a Monte-Carlo simulation of a tomographic NSECT system to investigate the feasibility of imaging the spatial distribution of liver iron through tomography. A simulation of an NSECT system has been designed in GEANT4 and used to tomographically scan a simulated human liver phantom with high-concentration iron lesions. Images are reconstructed with the MLEM algorithm and analyzed for pixel values within iron regions to determine the statistical significance of detection. Analysis results indicate that a wet iron concentration of 3 mg/g can be detected in surrounding liver tissue with p-value <= 0.0001 for neutron exposure corresponding to a radiation dose of 0.72 mSv. The research performed here demonstrates that NSECT has the ability to image clinically relevant distributions of iron through tomographic scanning.

  1. VIDA: A Voxel-Based Dosimetry Method for Targeted Radionuclide Therapy Using Geant4

    PubMed Central

    Dewaraja, Yuni K.; Abramson, Richard G.; Stabin, Michael G.

    2015-01-01

    Abstract We have developed the Voxel-Based Internal Dosimetry Application (VIDA) to provide patient-specific dosimetry in targeted radionuclide therapy performing Monte Carlo simulations of radiation transport with the Geant4 toolkit. The code generates voxel-level dose rate maps using anatomical and physiological data taken from individual patients. Voxel level dose rate curves are then fit and integrated to yield a spatial map of radiation absorbed dose. In this article, we present validation studies using established dosimetry results, including self-dose factors (DFs) from the OLINDA/EXM program for uniform activity in unit density spheres and organ self- and cross-organ DFs in the Radiation Dose Assessment Resource (RADAR) reference adult phantom. The comparison with reference data demonstrated agreement within 5% for self-DFs to spheres and reference phantom source organs for four common radionuclides used in targeted therapy (131I, 90Y, 111In, 177Lu). Agreement within 9% was achieved for cross-organ DFs. We also present dose estimates to normal tissues and tumors from studies of two non-Hodgkin Lymphoma patients treated by 131I radioimmunotherapy, with comparison to results generated independently with another dosimetry code. A relative difference of 12% or less was found between methods for mean absorbed tumor doses accounting for tumor regression. PMID:25594357

  2. Geant4 simulation study of Indian National Gamma Array at TIFR

    NASA Astrophysics Data System (ADS)

    Saha, S.; Palit, R.; Sethi, J.; Biswas, S.; Singh, P.

    2016-03-01

    A Geant4 simulation code for the Indian National Gamma Array (INGA) consisting of 24 Compton suppressed clover high purity germanium (HPGe) detectors has been developed. The calculated properties in the energy range that is of interest for nuclear γ-ray spectroscopy are spectral distributions for various standard radioactive sources, intrinsic peak efficiencies and peak-to-total (P/T) ratios in various configurations such as singles, add-back and Compton suppressed mode. The principle of operation of the detectors in add-back and Compton suppression mode have been reproduced in the simulation. The reliability of the calculation is checked by comparison with the experimental data for various γ-ray energies up to 5 MeV. The comparison between simulation results and experimental data demonstrate the need of incorporating the exact geometry of the clover detectors, Anti-Compton Shield and other surrounding materials in the array to explain the detector response to the γ-ray. Several experimental effects are also investigated. These include the geometrical correction to angular distribution, crosstalk probability and the impact of heavy metal collimators between the target and the array on the P/T ratio.

  3. Ion therapy for uveal melanoma in new human eye phantom based on GEANT4 toolkit.

    PubMed

    Mahdipour, Seyed Ali; Mowlavi, Ali Asghar

    2016-01-01

    Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth-dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8MeV proton, 190.1MeV alpha, and 1060MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam׳s Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.

  4. Geant4 simulation of the CERN-EU high-energy reference field (CERF) facility.

    PubMed

    Prokopovich, D A; Reinhard, M I; Cornelius, I M; Rosenfeld, A B

    2010-09-01

    The CERN-EU high-energy reference field facility is used for testing and calibrating both active and passive radiation dosemeters for radiation protection applications in space and aviation. Through a combination of a primary particle beam, target and a suitable designed shielding configuration, the facility is able to reproduce the neutron component of the high altitude radiation field relevant to the jet aviation industry. Simulations of the facility using the GEANT4 (GEometry ANd Tracking) toolkit provide an improved understanding of the neutron particle fluence as well as the particle fluence of other radiation components present. The secondary particle fluence as a function of the primary particle fluence incident on the target and the associated dose equivalent rates were determined at the 20 designated irradiation positions available at the facility. Comparisons of the simulated results with previously published simulations obtained using the FLUKA Monte Carlo code, as well as with experimental results of the neutron fluence obtained with a Bonner sphere spectrometer, are made.

  5. Monte Carlo study of a 3D Compton imaging device with GEANT4

    NASA Astrophysics Data System (ADS)

    Lenti, M.; Veltri, M.

    2011-10-01

    In this paper we investigate, with a detailed Monte Carlo simulation based on Geant4, the novel approach of Lenti (2008) [1] to 3D imaging with photon scattering. A monochromatic and well collimated gamma beam is used to illuminate the object to be imaged and the photons Compton scattered are detected by means of a surrounding germanium strip detector. The impact position and the energy of the photons are measured with high precision and the scattering position along the beam axis is calculated. We study as an application of this technique the case of brain imaging but the results can be applied as well to situations where a lighter object, with localized variations of density, is embedded in a denser container. We report here the attainable sensitivity in the detection of density variations as a function of the beam energy, the depth inside the object and size and density of the inclusions. Using a 600 keV gamma beam, for an inclusion with a density increase of 30% with respect to the surrounding tissue and thickness along the beam of 5 mm, we obtain at midbrain position a resolution of about 2 mm and a contrast of 12%. In addition the simulation indicates that for the same gamma beam energy a complete brain scan would result in an effective dose of about 1 mSv.

  6. Ion therapy for uveal melanoma in new human eye phantom based on GEANT4 toolkit

    SciTech Connect

    Mahdipour, Seyed Ali; Mowlavi, Ali Asghar

    2016-07-01

    Radiotherapy with ion beams like proton and carbon has been used for treatment of eye uveal melanoma for many years. In this research, we have developed a new phantom of human eye for Monte Carlo simulation of tumors treatment to use in GEANT4 toolkit. Total depth−dose profiles for the proton, alpha, and carbon incident beams with the same ranges have been calculated in the phantom. Moreover, the deposited energy of the secondary particles for each of the primary beams is calculated. The dose curves are compared for 47.8 MeV proton, 190.1 MeV alpha, and 1060 MeV carbon ions that have the same range in the target region reaching to the center of tumor. The passively scattered spread-out Bragg peak (SOBP) for each incident beam as well as the flux curves of the secondary particles including neutron, gamma, and positron has been calculated and compared for the primary beams. The high sharpness of carbon beam's Bragg peak with low lateral broadening is the benefit of this beam in hadrontherapy but it has disadvantages of dose leakage in the tail after its Bragg peak and high intensity of neutron production. However, proton beam, which has a good conformation with tumor shape owing to the beam broadening caused by scattering, can be a good choice for the large-size tumors.

  7. GATE as a GEANT4-based Monte Carlo platform for the evaluation of proton pencil beam scanning treatment plans

    NASA Astrophysics Data System (ADS)

    Grevillot, L.; Bertrand, D.; Dessy, F.; Freud, N.; Sarrut, D.

    2012-07-01

    Active scanning delivery systems take full advantage of ion beams to best conform to the tumor and to spare surrounding healthy tissues; however, it is also a challenging technique for quality assurance. In this perspective, we upgraded the GATE/GEANT4 Monte Carlo platform in order to recalculate the treatment planning system (TPS) dose distributions for active scanning systems. A method that allows evaluating the TPS dose distributions with the GATE Monte Carlo platform has been developed and applied to the XiO TPS (Elekta), for the IBA proton pencil beam scanning (PBS) system. First, we evaluated the specificities of each dose engine. A dose-conversion scheme that allows one to convert dose to medium into dose to water was implemented within GATE. Specific test cases in homogeneous and heterogeneous configurations allowed for the estimation of the differences between the beam models implemented in XiO and GATE. Finally, dose distributions of a prostate treatment plan were compared. In homogeneous media, a satisfactory agreement was generally obtained between XiO and GATE. The maximum stopping power difference of 3% occurred in a human tissue of 0.9 g cm-3 density and led to a significant range shift. Comparisons in heterogeneous configurations pointed out the limits of the TPS dose calculation accuracy and the superiority of Monte Carlo simulations. The necessity of computing dose to water in our Monte Carlo code for comparisons with TPSs is also presented. Finally, the new capabilities of the platform are applied to a prostate treatment plan and dose differences between both dose engines are analyzed in detail. This work presents a generic method to compare TPS dose distributions with the GATE Monte Carlo platform. It is noteworthy that GATE is also a convenient tool for imaging applications, therefore opening new research possibilities for the PBS modality.

  8. GATE as a GEANT4-based Monte Carlo platform for the evaluation of proton pencil beam scanning treatment plans.

    PubMed

    Grevillot, L; Bertrand, D; Dessy, F; Freud, N; Sarrut, D

    2012-07-07

    Active scanning delivery systems take full advantage of ion beams to best conform to the tumor and to spare surrounding healthy tissues; however, it is also a challenging technique for quality assurance. In this perspective, we upgraded the GATE/GEANT4 Monte Carlo platform in order to recalculate the treatment planning system (TPS) dose distributions for active scanning systems. A method that allows evaluating the TPS dose distributions with the GATE Monte Carlo platform has been developed and applied to the XiO TPS (Elekta), for the IBA proton pencil beam scanning (PBS) system. First, we evaluated the specificities of each dose engine. A dose-conversion scheme that allows one to convert dose to medium into dose to water was implemented within GATE. Specific test cases in homogeneous and heterogeneous configurations allowed for the estimation of the differences between the beam models implemented in XiO and GATE. Finally, dose distributions of a prostate treatment plan were compared. In homogeneous media, a satisfactory agreement was generally obtained between XiO and GATE. The maximum stopping power difference of 3% occurred in a human tissue of 0.9 g cm(-3) density and led to a significant range shift. Comparisons in heterogeneous configurations pointed out the limits of the TPS dose calculation accuracy and the superiority of Monte Carlo simulations. The necessity of computing dose to water in our Monte Carlo code for comparisons with TPSs is also presented. Finally, the new capabilities of the platform are applied to a prostate treatment plan and dose differences between both dose engines are analyzed in detail. This work presents a generic method to compare TPS dose distributions with the GATE Monte Carlo platform. It is noteworthy that GATE is also a convenient tool for imaging applications, therefore opening new research possibilities for the PBS modality.

  9. Evaluation of open MPI and MPICH2 performances for the computation time in proton therapy dose calculations with Geant4

    NASA Astrophysics Data System (ADS)

    Kazemi, M.; Afarideh, H.; Riazi, Z.

    2015-11-01

    The aim of this research work is to use a better parallel software structure to improve the performance of the Monte Carlo Geant4 code in proton treatment planning. The hadron therapy simulation is rewritten to parallelize the shared memory multiprocessor systems by using the Message-Passing Interface (MPI). The speedup performance of the code has been studied by using two MPI-compliant libraries including Open MPI and the MPICH2, separately. Despite the speedup, the results are almost linear for both the Open MPI and MPICH2; the latter was chosen because of its better characteristics and lower computation time. The Geant4 parameters, including the step limiter and the set cut, have been analyzed to minimize the simulation time as much as possible. For a reasonable compromise between the spatial dose distribution and the calculation time, the improvement in time reduction coefficient reaches about 157.

  10. GEANT4 Detector Simulations:. Radiation Interaction Simulations for the High-Energy Astrophysics Experiments Euso and AMS

    NASA Astrophysics Data System (ADS)

    Gonçalves, Patrícia

    2006-02-01

    The system architecture of a GEANT4 based simulation framework and its application to EUSO/ULTRA and AMS/RICH performance studies are presented. ULTRA (Ultraviolet Light Transmission and Reflection in the Atmosphere) is an experimental support activity of EUSO (Extreme Universe Space Observatory), an experiment devoted to the study of extreme energy cosmic rays and neutrinos. Relevant aspects of the ULTRA simulation, namely the description of optical processes and the simulation of Fresnel lenses using parameterisation/replication techniques are described. The RICH (Ring Imaging CHerenkov detector) of the AMS (Alpha Magnetic Spectrometer) experiment, will incorporate a dual radiator, made of a low refractive index material, aerogel, and of sodium fluoride (NaF). A more realistic description of Cherenkov photon transmission through the aerogel surface, based on Atomic Force Microscopy images, was implemented in GEANT4.

  11. Assessment of patient dose reduction by bismuth shielding in CT using measurements, GEANT4 and MCNPX simulations.

    PubMed

    Mendes, M; Costa, F; Figueira, C; Madeira, P; Teles, P; Vaz, P

    2015-07-01

    This work reports on the use of two different Monte Carlo codes (GEANT4 and MCNPX) for assessing the dose reduction using bismuth shields in computer tomography (CT) procedures in order to protect radiosensitive organs such as eye lens, thyroid and breast. Measurements were performed using head and body PMMA phantoms and an ionisation chamber placed in five different positions of the phantom. Simulations were performed to estimate Computed Tomography Dose Index values using GEANT4 and MCNPX. The relative differences between measurements and simulations were <10 %. The dose reduction arising from the use of bismuth shielding ranges from 2 to 45 %, depending on the position of the bismuth shield. The percentage of dose reduction was more significant for the area covered by the bismuth shielding (36 % for eye lens, 39 % for thyroid and 45 % for breast shields).

  12. The simulation of the LANFOS-H food radiation contamination detector using Geant4 package

    NASA Astrophysics Data System (ADS)

    Piotrowski, Lech Wiktor; Casolino, Marco; Ebisuzaki, Toshikazu; Higashide, Kazuhiro

    2015-02-01

    Recent incident in the Fukushima power plant caused a growing concern about the radiation contamination and resulted in lowering the Japanese limits for the permitted amount of 137Cs in food to 100 Bq/kg. To increase safety and ease the concern we are developing LANFOS (Large Food Non-destructive Area Sampler)-a compact, easy to use detector for assessment of radiation in food. Described in this paper LANFOS-H has a 4 π coverage to assess the amount of 137Cs present, separating it from the possible 40K food contamination. Therefore, food samples do not have to be pre-processed prior to a test and can be consumed after measurements. It is designed for use by non-professionals in homes and small institutions such as schools, showing safety of the samples, but can be also utilized by specialists providing radiation spectrum. Proper assessment of radiation in food in the apparatus requires estimation of the γ conversion factor of the detectors-how many γ photons will produce a signal. In this paper we show results of the Monte Carlo estimation of this factor for various approximated shapes of fish, vegetables and amounts of rice, performed with Geant4 package. We find that the conversion factor combined from all the detectors is similar for all food types and is around 37%, varying maximally by 5% with sample length, much less than for individual detectors. The different inclinations and positions of samples in the detector introduce uncertainty of 1.4%. This small uncertainty validates the concept of a 4 π non-destructive apparatus.

  13. Geant4 simulations on medical Linac operation at 18 MV: Experimental validation based on activation foils

    NASA Astrophysics Data System (ADS)

    Vagena, E.; Stoulos, S.; Manolopoulou, M.

    2016-03-01

    The operation of a medical linear accelerator was simulated using the Geant4 code regarding to study the characteristics of an 18 MeV photon beam. Simulations showed that (a) the photon spectrum at the isocenter is not influenced by changes of the primary electron beam's energy distribution and spatial spread (b) 98% of the photon energy fluence scored at the isocenter is primary photons that have only interacted with the target (c) the number of contaminant electrons is not negligible since it fluctuated around 5×10-5 per primary electron or 2.40×10-3 per photon at the isocenter (d) the number of neutrons that are created by (γ, n) reactions is 3.13×10-6 per primary electron or 1.50×10-3 per photon at the isocenter (e) a flattening filter free beam needs less primary electrons in order to deliver the same photon fluence at the isocenter than a normal flattening filter operation (f) there is no significant increase of the surface dose due to the contaminant electrons by removing the flattening filter (g) comparing the neutron fluences per incident electron for the flattened and unflattened beam, the neutron fluencies is 7% higher for the unflattened beams. To validate the simulations results, the total neutron and photon fluence at the isocenter field were measured using nickel, indium, and natural uranium activation foils. The percentage difference between simulations and measurements was 1.26% in case of uranium and 2.45% in case of the indium foil regarding photon fluencies while for neutrons the discrepancy is higher up to 8.0%. The photon and neutron fluencies of the simulated experiments fall within a range of ±1 and ±2 sigma error, respectively, compared to the ones obtained experimentally.

  14. Investigation of OPET Performance Using GATE, a Geant4-Based Simulation Software.

    PubMed

    Rannou, Fernando R; Kohli, Vandana; Prout, David L; Chatziioannou, Arion F

    2004-10-01

    A combined optical positron emission tomography (OPET) system is capable of both optical and PET imaging in the same setting, and it can provide information/interpretation not possible in single-mode imaging. The scintillator array here serves the dual function of coupling the optical signal from bioluminescence/fluorescence to the photodetector and also of channeling optical scintillations from the gamma rays. We report simulation results of the PET part of OPET using GATE, a Geant4 simulation package. The purpose of this investigation is the definition of the geometric parameters of the OPET tomograph. OPET is composed of six detector blocks arranged in a hexagonal ring-shaped pattern with an inner radius of 15.6 mm. Each detector consists of a two-dimensional array of 8 × 8 scintillator crystals each measuring 2 × 2 × 10 mm(3). Monte Carlo simulations were performed using the GATE software to measure absolute sensitivity, depth of interaction, and spatial resolution for two ring configurations, with and without gantry rotations, two crystal materials, and several crystal lengths. Images were reconstructed with filtered backprojection after angular interleaving and transverse one-dimensional interpolation of the sinogram. We report absolute sensitivities nearly seven times that of the prototype microPET at the center of field of view and 2.0 mm tangential and 2.3 mm radial resolutions with gantry rotations up to an 8.0 mm radial offset. These performance parameters indicate that the imaging spatial resolution and sensitivity of the OPET system will be suitable for high-resolution and high-sensitivity small-animal PET imaging.

  15. Validation of the Geant4 Monte Carlo package for X-ray fluorescence spectroscopy in triaxial geometry

    NASA Astrophysics Data System (ADS)

    Amaro, Pedro; Santos, José Paulo; Samouco, Ana; Adão, Ricardo; Martins, Luís Souto; Weber, Sebastian; Tashenov, Stanislav; Carvalho, Maria Luisa; Pessanha, Sofia

    2017-04-01

    In this study, we investigated the potential of the Geant4 Monte Carlo simulation package for retrieving accurate elemental concentrations from energy dispersive X-ray fluorescence spectra. For this purpose, we implemented a Geant4 code that simulates an energy dispersive X-ray fluorescence spectrometer in a triaxial geometry. In parallel, we also performed measurements in a spectrometer with the same geometry, for validation of the present code. This spectrometer allows low limits of detection and permits an effective comparison of elemental concentrations down to tens of part-per-million. Several standard reference materials of both light, medium and heavy matrices were employed in order to attest the validity of simulations for several values of averaged atomic number. We observed good agreement of better than 25% for most fluorescence lines of interest, and for all materials. Discrepancies were observed at the multiple Compton scattering tail. We thus concluded from this experimental and theoretical study that the present Geant4 code can be incorporated in a quantitative method for the determination of trace elements in a triaxial-type spectrometer.

  16. PDB4DNA: Implementation of DNA geometry from the Protein Data Bank (PDB) description for Geant4-DNA Monte-Carlo simulations

    NASA Astrophysics Data System (ADS)

    Delage, E.; Pham, Q. T.; Karamitros, M.; Payno, H.; Stepan, V.; Incerti, S.; Maigne, L.; Perrot, Y.

    2015-07-01

    This paper describes PDB4DNA, a new Geant4 user application, based on an independent, cross-platform, free and open source C++ library, so-called PDBlib, which enables use of atomic level description of DNA molecule in Geant4 Monte Carlo particle transport simulations. For the evaluation of direct damage induced on the DNA molecule by ionizing particles, the application makes use of an algorithm able to determine the closest atom in the DNA molecule to energy depositions. Both the PDB4DNA application and the PDBlib library are available as free and open source under the Geant4 license.

  17. Simulation of the radiation exposure in space during a large solar energetic particle event with GEANT4

    NASA Astrophysics Data System (ADS)

    Matthiä, Daniel; Berger, Thomas; Puchalska, Monika; Reitz, Guenther

    in August 1972 in the energy range from 45 MeV to 1 GeV. The transport calculations of the energetic particles through the shielding and the phantom model were performed using the Monte-Carlo code GEANT4.

  18. TH-E-BRE-01: A 3D Solver of Linear Boltzmann Transport Equation Based On a New Angular Discretization Method with Positivity for Photon Dose Calculation Benchmarked with Geant4

    SciTech Connect

    Hong, X; Gao, H

    2014-06-15

    Purpose: The Linear Boltzmann Transport Equation (LBTE) solved through statistical Monte Carlo (MC) method provides the accurate dose calculation in radiotherapy. This work is to investigate the alternative way for accurately solving LBTE using deterministic numerical method due to its possible advantage in computational speed from MC. Methods: Instead of using traditional spherical harmonics to approximate angular scattering kernel, our deterministic numerical method directly computes angular scattering weights, based on a new angular discretization method that utilizes linear finite element method on the local triangulation of unit angular sphere. As a Result, our angular discretization method has the unique advantage in positivity, i.e., to maintain all scattering weights nonnegative all the time, which is physically correct. Moreover, our method is local in angular space, and therefore handles the anisotropic scattering well, such as the forward-peaking scattering. To be compatible with image-guided radiotherapy, the spatial variables are discretized on the structured grid with the standard diamond scheme. After discretization, the improved sourceiteration method is utilized for solving the linear system without saving the linear system to memory. The accuracy of our 3D solver is validated using analytic solutions and benchmarked with Geant4, a popular MC solver. Results: The differences between Geant4 solutions and our solutions were less than 1.5% for various testing cases that mimic the practical cases. More details are available in the supporting document. Conclusion: We have developed a 3D LBTE solver based on a new angular discretization method that guarantees the positivity of scattering weights for physical correctness, and it has been benchmarked with Geant4 for photon dose calculation.

  19. Studying the response of a plastic scintillator to gamma rays using the Geant4 Monte Carlo code.

    PubMed

    Ghadiri, Rasoul; Khorsandi, Jamshid

    2015-05-01

    To determine the gamma ray response function of an NE-102 scintillator and to investigate the gamma spectra due to the transport of optical photons, we simulated an NE-102 scintillator using Geant4 code. The results of the simulation were compared with experimental data. Good consistency between the simulation and data was observed. In addition, the time and spatial distributions, along with the energy distribution and surface treatments of scintillation detectors, were calculated. This simulation makes us capable of optimizing the photomultiplier tube (or photodiodes) position to yield the best coupling to the detector. Copyright © 2015 Elsevier Ltd. All rights reserved.

  20. Intercomparision of Monte Carlo Radiation Transport Codes MCNPX, GEANT4, and FLUKA for Simulating Proton Radiotherapy of the Eye

    PubMed Central

    Randeniya, S. D.; Taddei, P. J.; Newhauser, W. D.; Yepes, P.

    2010-01-01

    Monte Carlo simulations of an ocular treatment beam-line consisting of a nozzle and a water phantom were carried out using MCNPX, GEANT4, and FLUKA to compare the dosimetric accuracy and the simulation efficiency of the codes. Simulated central axis percent depth-dose profiles and cross-field dose profiles were compared with experimentally measured data for the comparison. Simulation speed was evaluated by comparing the number of proton histories simulated per second using each code. The results indicate that all the Monte Carlo transport codes calculate sufficiently accurate proton dose distributions in the eye and that the FLUKA transport code has the highest simulation efficiency. PMID:20865141

  1. Creation of a Geant4 Muon Tomography Package for Imaging of Nuclear Fuel in Dry Cask Storage

    SciTech Connect

    Tsoukalas, Lefteri H.

    2016-03-01

    This is the final report of the NEUP project “Creation of a Geant4 Muon Tomography Package for Imaging of Nuclear Fuel in Dry Cask Storage”, DE-NE0000695. The project started on December 1, 2013 and this report covers the period December 1, 2013 through November 30, 2015. The project was successfully completed and this report provides an overview of the main achievements, results and findings throughout the duration of the project. Additional details can be found in the main body of this report and on the individual Quarterly Reports and associated Deliverables of the project, uploaded in PICS-NE.

  2. Accuracy of EGSnrc, Geant4 and PENELOPE Monte Carlo systems for simulation of electron scatter in external beam radiotherapy

    PubMed Central

    Faddegon, Bruce A; Kawrakow, Iwan; Kubyshin, Yuri; Perl, Joseph; Sempau, Josep; Urban, Laszlo

    2012-01-01

    Three widely used Monte Carlo systems were benchmarked against recently published measurements of the angular distribution of 13 MeV and 20 MeV electrons scattered from foils of different atomic number and thickness. Source and geometry was simulated in detail to calculate electron fluence profiles 118.2 cm from the exit window. Results were compared to the measured fluence profiles and the characteristic angle where the fluence drops to 1/e of its maximum value. EGSnrc and PENELOPE results, on average, agreed with measurement within 1 standard deviation experimental uncertainty, with EGSnrc estimating slightly lower scatter than measurement, PENELOPE slightly higher scatter. Geant4.9.2 overestimated the characteristic angle for the lower atomic number foils by as much as 10%. Retuning of the scatter distributions in Geant4 led to a much better agreement with measurement, close to that achieved with the other codes. The 3% differences from measurement seen with all codes for at least some of the foils would result in clinically significant errors in the fluence profiles (2%/4 mm), given accurate knowledge of the electron source and treatment head geometry used in radiotherapy. Further improvement in simulation accuracy is needed to achieve 1%/1 mm agreement with measurement for the full range of beam energies, foil atomic number and thickness used in radiotherapy. EGSnrc would achieve this accuracy with an increase in thickness of the mylar sheets in the monitor chamber, Penelope with a decrease in thickness. PMID:19779217

  3. Inhomogeneity effect in Varian Trilogy Clinac iX 10 MV photon beam using EGSnrc and Geant4 code system

    NASA Astrophysics Data System (ADS)

    Yani, S.; Rhani, M. F.; Haryanto, F.; Arif, I.

    2016-08-01

    Treatment fields consist of tissue other than water equivalent tissue (soft tissue, bones, lungs, etc.). The inhomogeneity effect can be investigated by Monte Carlo (MC) simulation. MC simulation of the radiation transport in an absorbing medium is the most accurate method for dose calculation in radiotherapy. The aim of this work is to evaluate the effect of inhomogeneity phantom on dose calculations in photon beam radiotherapy obtained by different MC codes. MC code system EGSnrc and Geant4 was used in this study. Inhomogeneity phantom dimension is 39.5 × 30.5 × 30 cm3 and made of 4 material slices (12.5 cm water, 10 cm aluminium, 5 cm lung and 12.5 cm water). Simulations were performed for field size 4 × 4 cm2 at SSD 100 cm. The spectrum distribution Varian Trilogy Clinac iX 10 MV was used. Percent depth dose (PDD) and dose profile was investigated in this research. The effects of inhomogeneities on radiation dose distributions depend on the amount, density and atomic number of the inhomogeneity, as well as on the quality of the photon beam. Good agreement between dose distribution from EGSnrc and Geant4 code system in inhomogeneity phantom was observed, with dose differences around 5% and 7% for depth doses and dose profiles.

  4. Geant4 Simulations of SuperCDMS iZip Detector Charge Carrier Propagation and FET Readout

    NASA Astrophysics Data System (ADS)

    Agnese, Rob

    2013-04-01

    The SuperCDMS experiment aims to directly detect dark matter particles called WIMPs (Weakly Interacting Massive Particles). The detectors collect phonon and ionization energy of incident particles for analysis. The SuperCDMS Detector Monte Carlo group is implementing low temperature phonon and ionization simulations in Geant4 in order to study the response of the detectors to incident events. Phonons and electron-hole pairs are tracked in a low temperature crystal detector. The resulting TES phonon readout, as well as the FET charge readout are simulated. The Geant4 framework is well-suited to these tasks. The charge transport in the presence of a complex electric field is performed by calculating a tetrahedral mesh of potentials across the crystal volume. To calculate the FET readout, the Shockley-Ramo theorem is applied to simulate the current in the FET. The focus of this presentation will be on incorporating and using the software package, Qhull, to calculate a tetrahedral mesh from known potentials and then using barycentric coordinates to perform a linear interpolation to calculate the field. After calculating the field at each charge carrier's position, the Shockley-Ramo theorem is applied and the previous triangulation technique is performed to simulate the FET response

  5. Layered mass geometry: a novel technique to overlay seeds and applicators onto patient geometry in Geant4 brachytherapy simulations

    NASA Astrophysics Data System (ADS)

    Enger, Shirin A.; Landry, Guillaume; D'Amours, Michel; Verhaegen, Frank; Beaulieu, Luc; Asai, Makoto; Perl, Joseph

    2012-10-01

    A problem faced by all Monte Carlo (MC) particle transport codes is how to handle overlapping geometries. The Geant4 MC toolkit allows the user to create parallel geometries within a single application. In Geant4 the standard mass-containing geometry is defined in a simulation volume called the World Volume. Separate parallel geometries can be defined in parallel worlds, that is, alternate three dimensional simulation volumes that share the same coordinate system with the World Volume for geometrical event biasing, scoring of radiation interactions, and/or the creation of hits in detailed readout structures. Until recently, only one of those worlds could contain mass so these parallel worlds provided no solution to simplify a complex geometric overlay issue in brachytherapy, namely the overlap of radiation sources and applicators with a CT based patient geometry. The standard method to handle seed and applicator overlay in MC requires removing CT voxels whose boundaries would intersect sources, placing the sources into the resulting void and then backfilling the remaining space of the void with a relevant material. The backfilling process may degrade the accuracy of patient representation, and the geometrical complexity of the technique precludes using fast and memory-efficient coding techniques that have been developed for regular voxel geometries. The patient must be represented by the less memory and CPU-efficient Geant4 voxel placement technique, G4PVPlacement, rather than the more efficient G4NestedParameterization (G4NestedParam). We introduce for the first time a Geant4 feature developed to solve this issue: Layered Mass Geometry (LMG) whereby both the standard (CT based patient geometry) and the parallel world (seeds and applicators) may now have mass. For any area where mass is present in the parallel world, the parallel mass is used. Elsewhere, the mass of the standard world is used. With LMG the user no longer needs to remove patient CT voxels that would

  6. Layered mass geometry: a novel technique to overlay seeds and applicators onto patient geometry in Geant4 brachytherapy simulations.

    PubMed

    Enger, Shirin A; Landry, Guillaume; D'Amours, Michel; Verhaegen, Frank; Beaulieu, Luc; Asai, Makoto; Perl, Joseph

    2012-10-07

    A problem faced by all Monte Carlo (MC) particle transport codes is how to handle overlapping geometries. The Geant4 MC toolkit allows the user to create parallel geometries within a single application. In Geant4 the standard mass-containing geometry is defined in a simulation volume called the World Volume. Separate parallel geometries can be defined in parallel worlds, that is, alternate three dimensional simulation volumes that share the same coordinate system with the World Volume for geometrical event biasing, scoring of radiation interactions, and/or the creation of hits in detailed readout structures. Until recently, only one of those worlds could contain mass so these parallel worlds provided no solution to simplify a complex geometric overlay issue in brachytherapy, namely the overlap of radiation sources and applicators with a CT based patient geometry. The standard method to handle seed and applicator overlay in MC requires removing CT voxels whose boundaries would intersect sources, placing the sources into the resulting void and then backfilling the remaining space of the void with a relevant material. The backfilling process may degrade the accuracy of patient representation, and the geometrical complexity of the technique precludes using fast and memory-efficient coding techniques that have been developed for regular voxel geometries. The patient must be represented by the less memory and CPU-efficient Geant4 voxel placement technique, G4PVPlacement, rather than the more efficient G4NestedParameterization (G4NestedParam). We introduce for the first time a Geant4 feature developed to solve this issue: Layered Mass Geometry (LMG) whereby both the standard (CT based patient geometry) and the parallel world (seeds and applicators) may now have mass. For any area where mass is present in the parallel world, the parallel mass is used. Elsewhere, the mass of the standard world is used. With LMG the user no longer needs to remove patient CT voxels that would

  7. Modeling the Tagged-Neutron UXO Identification Technique Using the Geant4 Toolkit

    DTIC Science & Technology

    2011-01-01

    fat and water by 14 MeV neutron activation analysis —a feasibility study. Phys Med Biol 40(6):1045–1055 4. Chichester DL, Lemchak M, Simpson JD (2005...characteristic gamma - rays, and (c) 2D and 3D-image reconstruction of the interrogated object using the neutron and gamma -ray time- of-flight information. Using...C), nitrogen (N) and oxygen (O) in the material, particularly N which is unique to HE [1]. The pulsed elemental analysis with neutrons (PELAN) system

  8. A Geant4-based Simulation to Evaluate the Feasibility of Using Nuclear Resonance Fluorescence (NRF) in Determining Atomic Compositions of Body Tissue in Cancer Diagnostics and Irradiation

    NASA Astrophysics Data System (ADS)

    Gilbo, Yekaterina; Wijesooriya, Krishni; Liyanage, Nilanga

    2017-01-01

    Customarily applied in homeland security for identifying concealed explosives and chemical weapons, NRF (Nuclear Resonance Fluorescence) may have high potential in determining atomic compositions of body tissue. High energy photons incident on a target excite the target nuclei causing characteristic re-emission of resonance photons. As the nuclei of each isotope have well-defined excitation energies, NRF uniquely indicates the isotopic content of the target. NRF radiation corresponding to nuclear isotopes present in the human body is emitted during radiotherapy based on Bremsstrahlung photons generated in a linear electron accelerator. We have developed a Geant4 simulation in order to help assess NRF capabilities in detecting, mapping, and characterizing tumors. We have imported a digital phantom into the simulation using anatomical data linked to known chemical compositions of various tissues. Work is ongoing to implement the University of Virginia's cancer center treatment setup and patient geometry, and to collect and analyze the simulation's physics quantities to evaluate the potential of NRF for medical imaging applications. Preliminary results will be presented.

  9. A GEANT4 study on the time resolution of a fast plastic scintillator read out by a G-APD

    NASA Astrophysics Data System (ADS)

    Sedlak, K.; Stoykov, A.; Scheuermann, R.

    2012-12-01

    The time resolution of a fast scintillation counter, consisting of a plastic scintillator read out by a Geiger-mode Avalanche Photodiode, is studied over a wide range of the number of detected photons (primary photoelectrons) using the GEANT4 simulation toolkit. Different timing definitions such as first photon detection, leading edge and constant fraction discrimination are considered. In the latter case the predictions are compared with the existing experimental data. We also show that due to the finite scintillation rise time, finite scintillator dimensions and also due to the finite single photon time resolution in G-APD cells, the time resolution for the first detected photon in real detectors substantially deviates from the σ˜1/Nphe dependence, theoretically predicted for a scintillator with zero rise time.

  10. Design of Cherenkov bars for the optical part of the time-of-flight detector in Geant4.

    PubMed

    Nozka, L; Brandt, A; Rijssenbeek, M; Sykora, T; Hoffman, T; Griffiths, J; Steffens, J; Hamal, P; Chytka, L; Hrabovsky, M

    2014-11-17

    We present the results of studies devoted to the development and optimization of the optical part of a high precision time-of-flight (TOF) detector for the Large Hadron Collider (LHC). This work was motivated by a proposal to use such a detector in conjunction with a silicon detector to tag and measure protons from interactions of the type p + p → p + X + p, where the two outgoing protons are scattered in the very forward directions. The fast timing detector uses fused silica (quartz) bars that emit Cherenkov radiation as a relativistic particle passes through and the emitted Cherenkov photons are detected by, for instance, a micro-channel plate multi-anode Photomultiplier Tube (MCP-PMT). Several possible designs are implemented in Geant4 and studied for timing optimization as a function of the arrival time, and the number of Cherenkov photons reaching the photo-sensor.

  11. COMPARISON OF PARTICLE-TRACKING FEATURES IN GEANT4 AND MCNPX CODES FOR APPLICATIONS IN MAPPING OF PROTON RANGE UNCERTAINTY

    PubMed Central

    BEDNARZ, BRYAN; CHEN, GTY; PAGANETTI, HARALD; HAN, BIN; DING, AIPING; XU, X. GEORGE

    2012-01-01

    The accuracy of proton therapy is partially limited by uncertainties that result from changing pathological conditions in the patient such as tumor motion and shrinkage. These uncertainties can be minimized with the help of a time-resolved range telescope. Monte Carlo methods can help improve the performance of range telescopes by tracking proton interactions on a particle-by-particle basis thus broadening our understanding on the behavior of protons within the patient and the detector. This paper compared the proton multiple coulomb scattering algorithms in the Monte Carlo codes MCNPX and Geant4 to well-established scattering theories. We focus only on beam energies associated with proton imaging. Despite slight discrepancies between scattering algorithms, both codes appear to be capable of providing useful particle-tracking information for applications such as the proton range telescope. PMID:22389531

  12. Organ doses from hepatic radioembolization with 90Y, 153Sm, 166Ho and 177Lu: A Monte Carlo simulation study using Geant4

    NASA Astrophysics Data System (ADS)

    Hashikin, N. A. A.; Yeong, C. H.; Guatelli, S.; Abdullah, B. J. J.; Ng, K. H.; Malaroda, A.; Rosenfeld, A. B.; Perkins, A. C.

    2016-03-01

    90Y-radioembolization is a palliative treatment for liver cancer. 90Y decays via beta emission, making imaging difficult due to absence of gamma radiation. Since post-procedure imaging is crucial, several theranostic radionuclides have been explored as alternatives. However, exposures to gamma radiation throughout the treatment caused concern for the organs near the liver. Geant4 Monte Carlo simulation using MIRD Pamphlet 5 reference phantom was carried out. A spherical tumour with 4.3cm radius was modelled within the liver. 1.82GBq of 90Y sources were isotropically distributed within the tumour, with no extrahepatic shunting. The simulation was repeated with 153Sm, 166Ho and 177Lu. The estimated tumour doses for all radionuclides were 262.9Gy. Tumour dose equivalent to 1.82GBq 90Y can be achieved with 8.32, 5.83, and 4.44GBq for 153Sm, 166Ho and 177Lu, respectively. Normal liver doses by the other radionuclides were lower than 90Y, hence beneficial for normal tissue sparing. The organ doses from 153Sm and 177Lu were relatively higher due to higher gamma energy, but were still well below 1Gy. 166Ho, 177Lu and 153Sm offer useful gamma emission for post-procedure imaging. They show potential as 90Y substitutes, delivering comparable tumour doses, lower normal liver doses and other organs doses far below the tolerance limit.

  13. Calculation of direct effects of 60Co gamma rays on the different DNA structural levels: A simulation study using the Geant4-DNA toolkit

    NASA Astrophysics Data System (ADS)

    Tajik, Marjan; Rozatian, Amir S. H.; Semsarha, Farid

    2015-03-01

    In this study, simple single strand breaks (SSB) and double strand breaks (DSB) due to direct effects of the secondary electron spectrum of 60Co gamma rays on different organizational levels of a volume model of the B-DNA conformation have been calculated using the Geant4-DNA toolkit. Result of this study for the direct DSB yield shows a good agreement with other theoretical and experimental results obtained by both photons and their secondary electrons; however, in the case of SSB a noticeable difference can be observed. Moreover, regarding the almost constant yields of the direct strand breaks in the different structural levels of the DNA, calculated in this work, and compared with some theoretical studies, it can be deduced that the direct strand breaks yields depend mainly on the primary double helix structure of the DNA and the higher-order structures cannot have a noticeable effect on the direct DNA damage inductions by 60Co gamma rays. In contrast, a direct dependency between the direct SSB and DSB yields and the volume of the DNA structure has been found. Also, a further study on the histone proteins showed that they can play an important role in the trapping of low energy electrons without any significant effect on the direct DNA strand breaks inductions, at least in the range of energies used in the current study.

  14. Ray tracing simulations for the wide-field x-ray telescope of the Einstein Probe mission based on Geant4 and XRTG4

    NASA Astrophysics Data System (ADS)

    Zhao, Donghua; Zhang, Chen; Yuan, Weimin; Willingale, Richard; Ling, Zhixing; Feng, Hua; Li, Hong; Ji, Jianfeng; Wang, Wenxin; Zhang, Shuangnan

    2014-07-01

    Einstein Probe (EP) is a proposed small scientific satellite dedicated to time-domain astrophysics working in the soft X-ray band. It will discover transients and monitor variable objects in 0.5-4 keV, for which it will employ a very large instantaneous field-of-view (60° × 60°), along with moderate spatial resolution (FWHM ˜ 5 arcmin). Its wide-field imaging capability will be achieved by using established technology in novel lobster-eye optics. In this paper, we present Monte-Carlo simulations for the focusing capabilities of EP's Wide-field X-ray Telescope (WXT). The simulations are performed using Geant4 with an X-ray tracer which was developed by cosine (http://cosine.nl/) to trace X-rays. Our work is the first step toward building a comprehensive model with which the design of the X-ray optics and the ultimate sensitivity of the instrument can be optimized by simulating the X-ray tracing and radiation environment of the system, including the focal plane detector and the shielding at the same time.

  15. SU-E-T-531: Performance Evaluation of Multithreaded Geant4 for Proton Therapy Dose Calculations in a High Performance Computing Facility

    SciTech Connect

    Shin, J; Coss, D; McMurry, J; Farr, J; Faddegon, B

    2014-06-01

    Purpose: To evaluate the efficiency of multithreaded Geant4 (Geant4-MT, version 10.0) for proton Monte Carlo dose calculations using a high performance computing facility. Methods: Geant4-MT was used to calculate 3D dose distributions in 1×1×1 mm3 voxels in a water phantom and patient's head with a 150 MeV proton beam covering approximately 5×5 cm2 in the water phantom. Three timestamps were measured on the fly to separately analyze the required time for initialization (which cannot be parallelized), processing time of individual threads, and completion time. Scalability of averaged processing time per thread was calculated as a function of thread number (1, 100, 150, and 200) for both 1M and 50 M histories. The total memory usage was recorded. Results: Simulations with 50 M histories were fastest with 100 threads, taking approximately 1.3 hours and 6 hours for the water phantom and the CT data, respectively with better than 1.0 % statistical uncertainty. The calculations show 1/N scalability in the event loops for both cases. The gains from parallel calculations started to decrease with 150 threads. The memory usage increases linearly with number of threads. No critical failures were observed during the simulations. Conclusion: Multithreading in Geant4-MT decreased simulation time in proton dose distribution calculations by a factor of 64 and 54 at a near optimal 100 threads for water phantom and patient's data respectively. Further simulations will be done to determine the efficiency at the optimal thread number. Considering the trend of computer architecture development, utilizing Geant4-MT for radiotherapy simulations is an excellent cost-effective alternative for a distributed batch queuing system. However, because the scalability depends highly on simulation details, i.e., the ratio of the processing time of one event versus waiting time to access for the shared event queue, a performance evaluation as described is recommended.

  16. Technical Note: Implementation of biological washout processes within GATE/GEANT4—A Monte Carlo study in the case of carbon therapy treatments

    SciTech Connect

    Martínez-Rovira, I. Jouvie, C.; Jan, S.

    2015-04-15

    Purpose: The imaging of positron emitting isotopes produced during patient irradiation is the only in vivo method used for hadrontherapy dose monitoring in clinics nowadays. However, the accuracy of this method is limited by the loss of signal due to the metabolic decay processes (biological washout). In this work, a generic modeling of washout was incorporated into the GATE simulation platform. Additionally, the influence of the washout on the β{sup +} activity distributions in terms of absolute quantification and spatial distribution was studied. Methods: First, the irradiation of a human head phantom with a {sup 12}C beam, so that a homogeneous dose distribution was achieved in the tumor, was simulated. The generated {sup 11}C and {sup 15}O distribution maps were used as β{sup +} sources in a second simulation, where the PET scanner was modeled following a detailed Monte Carlo approach. The activity distributions obtained in the presence and absence of washout processes for several clinical situations were compared. Results: Results show that activity values are highly reduced (by a factor of 2) in the presence of washout. These processes have a significant influence on the shape of the PET distributions. Differences in the distal activity falloff position of 4 mm are observed for a tumor dose deposition of 1 Gy (T{sub ini} = 0 min). However, in the case of high doses (3 Gy), the washout processes do not have a large effect on the position of the distal activity falloff (differences lower than 1 mm). The important role of the tumor washout parameters on the activity quantification was also evaluated. Conclusions: With this implementation, GATE/GEANT 4 is the only open-source code able to simulate the full chain from the hadrontherapy irradiation to the PET dose monitoring including biological effects. Results show the strong impact of the washout processes, indicating that the development of better models and measurement of biological washout data are

  17. DETECTORS AND EXPERIMENTAL METHODS: Study of neutron response for two hybrid RPC setups using the GEANT4 MC simulation approach

    NASA Astrophysics Data System (ADS)

    M., Jamil; Rhee T., J.; Jeon J., Y.

    2009-10-01

    The present article describes a detailed neutron simulation study in the energy range 10-10 MeV to 1.0 GeV for two different RPC configurations. The simulation studies were taken by using the GEANT4 MC code. Aluminum was utilized on the GND and readout strips for the (a) Bakelite-based and (b) glass-based RPCs. For the former type of RPC setup the neutron sensitivity for the isotropic source was Sn = 2.702 × 10-2 at En = 1.0 GeV, while for the latter type of RPC, the neutron sensitivity for the same source was evaluated as Sn = 4.049 × 10-2 at En = 1.0 GeV. These results were further compared with the previous RPC configuration in which copper was used for ground and pickup pads. Additionally Al was employed at (GND+strips) of the phosphate glass RPC setup and compared with the copper-based phosphate glass RPC. Good agreement with sensitivity values was obtained with the current and previous simulation results.

  18. Geant4 Simulations of the SuperCDMS iZIP Detector Charge Carrier Propagation and FET Readout

    NASA Astrophysics Data System (ADS)

    Agnese, R.; Brandt, D.; Asai, M.; Cabrera, B.; Leman, S.; McCarthy, K.; Redl, P.; Saab, T.; Wright, D.

    2014-09-01

    The SuperCDMS experiment aims to directly detect dark matter particles called WIMPs (weakly interacting massive particles). The detectors measure phonon and ionization energy due to nuclear and electron recoils from incident particles. The SuperCDMS Detector Monte Carlo group uses Geant4 to simulate electron-hole pairs () and low temperature phonons. We use these simulations in order to study energy deposition in the detectors. Phonons and electron-hole pairs are tracked in a crystal detector. Because of the band structure of the crystals, the electrons undergo oblique propagation. The charge electrodes on each side of the detector are biased at different voltages while the phonon sensors are grounded. This creates a nearly uniform electric field through the bulk of the detector, with a complex shape near the surfaces. The electric field is calculated from interpolating on a tetrahedral mesh. The resulting TES phonon readout, as well as the FET charge readout are simulated. To calculate the FET readout, the Shockley-Ramo theorem is applied to simulate the current in the FET. The goal of this paper is to describe the theory and implementation of calculating the electric field, performing the charge carrier propagation, and simulating the FET readout of the SuperCDMS detectors.

  19. Simulation of the 6 MV Elekta Synergy Platform linac photon beam using Geant4 Application for Tomographic Emission

    PubMed Central

    Didi, Samir; Moussa, Abdelilah; Yahya, Tayalati; Mustafa, Zerfaoui

    2015-01-01

    The present work validates the Geant4 Application for Tomographic Emission Monte Carlo software for the simulation of a 6 MV photon beam given by Elekta Synergy Platform medical linear accelerator treatment head. The simulation includes the major components of the linear accelerator (LINAC) with multi-leaf collimator and a homogeneous water phantom. Calculations were performed for the photon beam with several treatment field sizes ranging from 5 cm × 5 cm to 30 cm × 30 cm at 100 cm distance from the source. The simulation was successfully validated by comparison with experimental distributions. Good agreement between simulations and measurements was observed, with dose differences of about 0.02% and 2.5% for depth doses and lateral dose profiles, respectively. This agreement was also emphasized by the Kolmogorov–Smirnov goodness-of-fit test and by the gamma-index comparisons where more than 99% of the points for all simulations fulfill the quality assurance criteria of 2 mm/2%. PMID:26500399

  20. Space radiation analysis: Radiation effects and particle interaction outside the Earth's magnetosphere using GRAS and GEANT4

    NASA Astrophysics Data System (ADS)

    Martinez, Lisandro M.; Kingston, Jennifer

    2012-03-01

    In order to explore the Moon and Mars it is necessary to investigate the hazards due to the space environment and especially ionizing radiation. According to previous papers, much information has been presented in radiation analysis inside the Earth's magnetosphere, but much of this work was not directly relevant to the interplanetary medium. This work intends to explore the effect of radiation on humans inside structures such as the ISS and provide a detailed analysis of galactic cosmic rays (GCRs) and solar proton events (SPEs) using SPENVIS (Space Environment Effects and Information System) and CREME96 data files for particle flux outside the Earth's magnetosphere. The simulation was conducted using GRAS, a European Space Agency (ESA) software based on GEANT4. Dose and equivalent dose have been calculated as well as secondary particle effects and GCR energy spectrum. The calculated total dose effects and equivalent dose indicate the risk and effects that space radiation could have on the crew, these values are calculated using two different types of structures, the ISS and the TransHab modules. Final results indicate the amounts of radiation expected to be absorbed by the astronauts during long duration interplanetary flights; this denotes importance of radiation shielding and the use of proper materials to reduce the effects.

  1. Simulation of the 6 MV Elekta Synergy Platform linac photon beam using Geant4 Application for Tomographic Emission.

    PubMed

    Didi, Samir; Moussa, Abdelilah; Yahya, Tayalati; Mustafa, Zerfaoui

    2015-01-01

    The present work validates the Geant4 Application for Tomographic Emission Monte Carlo software for the simulation of a 6 MV photon beam given by Elekta Synergy Platform medical linear accelerator treatment head. The simulation includes the major components of the linear accelerator (LINAC) with multi-leaf collimator and a homogeneous water phantom. Calculations were performed for the photon beam with several treatment field sizes ranging from 5 cm × 5 cm to 30 cm × 30 cm at 100 cm distance from the source. The simulation was successfully validated by comparison with experimental distributions. Good agreement between simulations and measurements was observed, with dose differences of about 0.02% and 2.5% for depth doses and lateral dose profiles, respectively. This agreement was also emphasized by the Kolmogorov-Smirnov goodness-of-fit test and by the gamma-index comparisons where more than 99% of the points for all simulations fulfill the quality assurance criteria of 2 mm/2%.

  2. 3D polymer gel dosimetry and Geant4 Monte Carlo characterization of novel needle based X-ray source

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Sozontov, E.; Safronov, V.; Gutman, G.; Strumban, E.; Jiang, Q.; Li, S.

    2010-11-01

    In the recent years, there have been a few attempts to develop a low energy x-ray radiation sources alternative to conventional radioisotopes used in brachytherapy. So far, all efforts have been centered around the intent to design an interstitial miniaturized x-ray tube. Though direct irradiation of tumors looks very promising, the known insertable miniature x-ray tubes have many limitations: (a) difficulties with focusing and steering the electron beam to the target; (b)necessity to cool the target to increase x-ray production efficiency; (c)impracticability to reduce the diameter of the miniaturized x-ray tube below 4mm (the requirement to decrease the diameter of the x-ray tube and the need to have a cooling system for the target have are mutually exclusive); (c) significant limitations in changing shape and energy of the emitted radiation. The specific aim of this study is to demonstrate the feasibility of a new concept for an insertable low-energy needle x-ray device based on simulation with Geant4 Monte Carlo code and to measure the dose rate distribution for low energy (17.5 keV) x-ray radiation with the 3D polymer gel dosimetry.

  3. Calibration and GEANT4 Simulations of the Phase II Proton Compute Tomography (pCT) Range Stack Detector

    SciTech Connect

    Uzunyan, S. A.; Blazey, G.; Boi, S.; Coutrakon, G.; Dyshkant, A.; Francis, K.; Hedin, D.; Johnson, E.; Kalnins, J.; Zutshi, V.; Ford, R.; Rauch, J. E.; Rubinov, P.; Sellberg, G.; Wilson, P.; Naimuddin, M.

    2015-12-29

    Northern Illinois University in collaboration with Fermi National Accelerator Laboratory (FNAL) and Delhi University has been designing and building a proton CT scanner for applications in proton treatment planning. The Phase II proton CT scanner consists of eight planes of tracking detectors with two X and two Y coordinate measurements both before and after the patient. In addition, a range stack detector consisting of a stack of thin scintillator tiles, arranged in twelve eight-tile frames, is used to determine the water equivalent path length (WEPL) of each track through the patient. The X-Y coordinates and WEPL are required input for image reconstruction software to find the relative (proton) stopping powers (RSP) value of each voxel in the patient and generate a corresponding 3D image. In this Note we describe tests conducted in 2015 at the proton beam at the Central DuPage Hospital in Warrenville, IL, focusing on the range stack calibration procedure and comparisons with the GEANT~4 range stack simulation.

  4. The investigation of prostatic calcifications using μ-PIXE analysis and their dosimetric effect in low dose rate brachytherapy treatments using Geant4.

    PubMed

    Pope, D J; Cutajar, D L; George, S P; Guatelli, S; Bucci, J A; Enari, K E; Miller, S; Siegele, R; Rosenfeld, A B

    2015-06-07

    Low dose rate brachytherapy is a widely used modality for the treatment of prostate cancer. Most clinical treatment planning systems currently in use approximate all tissue to water, neglecting the existence of inhomogeneities, such as calcifications. The presence of prostatic calcifications may perturb the dose due to the higher photoelectric effect cross section in comparison to water. This study quantitatively evaluates the effect of prostatic calcifications on the dosimetric outcome of brachytherapy treatments by means of Monte Carlo simulations and its potential clinical consequences.Four pathological calcification samples were characterised with micro-particle induced x-ray emission (μ-PIXE) to determine their heavy elemental composition. Calcium, phosphorus and zinc were found to be the predominant heavy elements in the calcification composition. Four clinical patient brachytherapy treatments were modelled using Geant4 based Monte Carlo simulations, in terms of the distribution of brachytherapy seeds and calcifications in the prostate. Dose reductions were observed to be up to 30% locally to the calcification boundary, calcification size dependent. Single large calcifications and closely placed calculi caused local dose reductions of between 30-60%. Individual calculi smaller than 0.5 mm in diameter showed minimal dosimetric impact, however, the effects of small or diffuse calcifications within the prostatic tissue could not be determined using the methods employed in the study. The simulation study showed a varying reduction on common dosimetric parameters. D90 showed a reduction of 2-5%, regardless of calcification surface area and volume. The parameters V100, V150 and V200 were also reduced by as much as 3% and on average by 1%. These reductions were also found to relate to the surface area and volume of calcifications, which may have a significant dosimetric impact on brachytherapy treatment, however, such impacts depend strongly on specific factors

  5. SU-E-T-203: Comparison of a Commercial MRI-Linear Accelerator Based Monte Carlo Dose Calculation Algorithm and Geant4

    SciTech Connect

    Ahmad, S; Sarfehnia, A; Paudel, M; Sahgal, A; Keller, B; Hissoiny, S

    2015-06-15

    Purpose: An MRI-linear accelerator is currently being developed by the vendor Elekta™. The treatment planning system that will be used to model dose for this unit uses a Monte Carlo dose calculation algorithm, GPUMCD, that allows for the application of a magnetic field. We tested this radiation transport code against an independent Monte-Carlo toolkit Geant4 (v.4.10.01) both with and without the magnetic field applied. Methods: The setup comprised a 6 MeV mono-energetic photon beam emerging from a point source impinging on a homogeneous water phantom at 100 cm SSD. The comparisons were drawn from the percentage depth doses (PDD) for three different field sizes (1.5 x 1.5 cm{sup 2}, 5 x 5 cm{sup 2}, 10 x 10 cm{sup 2}) and dose profiles at various depths. A 1.5 T magnetic field was applied perpendicular to the direction of the beam. The transport thresholds were kept the same for both codes. Results: All of the normalized PDDs and profiles agreed within ± 1 %. In the presence of the magnetic field, PDDs rise more quickly reducing the depth of maximum dose. Near the beam exit point in the phantom a hot spot is created due to the electron return effect. This effect is more pronounced for the larger field sizes. Profiles selected parallel to the external field show no effect, however, the ones selected perpendicular to the direction of the applied magnetic field are shifted towards the direction of the Lorentz force applied by the magnetic field on the secondary electrons. It is observed that these profiles are not symmetric which indicates a lateral build up of the dose. Conclusion: There is a good general agreement between the PDDs/profiles calculated by both algorithms thus far. We are proceeding towards clinically relevant comparisons in a heterogeneous phantom for polyenergetic beams. Funding for this work has been provided by Elekta.

  6. Benchmarking the Geant4 full system simulation of an associated alpha-particle detector for use in a D-T neutron generator.

    PubMed

    Zhang, Xiaodong; Hayward, Jason P; Cates, Joshua W; Hausladen, Paul A; Laubach, Mitchell A; Sparger, Johnathan E; Donnald, Samuel B

    2012-08-01

    The position-sensitive alpha-particle detector used to provide the starting time and initial direction of D-T neutrons in a fast-neutron imaging system was simulated with a Geant4-based Monte Carlo program. The whole detector system, which consists of a YAP:Ce scintillator, a fiber-optic faceplate, a light guide, and a position-sensitive photo-multiplier tube (PSPMT), was modeled, starting with incident D-T alphas. The scintillation photons, whose starting time follows the distribution of a scintillation decay curve, were produced and emitted uniformly into a solid angle of 4π along the track segments of the alpha and its secondaries. Through tracking all photons and taking into account the quantum efficiency of the photocathode, the number of photoelectrons and their time and position distributions were obtained. Using a four-corner data reconstruction formula, the flood images of the alpha detector with and without optical grease between the YAP scintillator and the fiber-optic faceplate were obtained, which show agreement with the experimental results. The reconstructed position uncertainties of incident alpha particles for both cases are 1.198 mm and 0.998 mm respectively across the sensitive area of the detector. Simulation results also show that comparing with other faceplates composed of 500 μm, 300 μm, and 100 μm fibers, the 10-μm-fiber faceplate is the best choice to build the detector for better position performance. In addition, the study of the background originating inside the D-T generator suggests that for 500-μm-thick YAP:Ce coated with 1-μm-thick aluminum, and very good signal-to-noise ratio can be expected through application of a simple threshold.

  7. SU-E-T-519: Emission of Secondary Particles From a PMMA Phantom During Proton Irradiation: A Simulation Study with the Geant4 Monte Carlo Toolkit

    SciTech Connect

    Lau, A; Chen, Y; Ahmad, S

    2014-06-01

    Purpose: Proton therapy exhibits several advantages over photon therapy due to depth-dose distributions from proton interactions within the target material. However, uncertainties associated with protons beam range in the patient limit the advantage of proton therapy applications. To quantify beam range, positron-emitting nuclei (PEN) and prompt gamma (PG) techniques have been developed. These techniques use de-excitation photons to describe the location of the beam in the patient. To develop a detector system for implementing the PG technique for range verification applications in proton therapy, we studied the yields, energy and angular distributions of the secondary particles emitted from a PMMA phantom. Methods: Proton pencil beams of various energies incident onto a PMMA phantom with dimensions of 5 x 5 x 50 cm3 were used for simulation with the Geant4 toolkit using the standard electromagnetic packages as well as the packages based on the binary-cascade nuclear model. The emitted secondary particles are analyzed . Results: For 160 MeV incident protons, the yields of secondary neutrons and photons per 100 incident protons were ~6 and ~15 respectively. Secondary photon energy spectrum showed several energy peaks in the range between 0 and 10 MeV. The energy peaks located between 4 and 6 MeV were attributed to originate from direct proton interactions with 12C (~ 4.4 MeV) and 16O (~ 6 MeV), respectively. Most of the escaping secondary neutrons were found to have energies between 10 and 100 MeV. Isotropic emissions were found for lower energy neutrons (<10 MeV) and photons for all energies, while higher energy neutrons were emitted predominantly in the forward direction. The yields of emitted photons and neutrons increased with the increase of incident proton energies. Conclusions: A detector system is currently being developed incorporating the yields, energy and angular distributions of secondary particles from proton interactions obtained from this study.

  8. Analysis of the track- and dose-averaged LET and LET spectra in proton therapy using the geant4 Monte Carlo code

    PubMed Central

    Guan, Fada; Peeler, Christopher; Bronk, Lawrence; Geng, Changran; Taleei, Reza; Randeniya, Sharmalee; Ge, Shuaiping; Mirkovic, Dragan; Grosshans, David; Mohan, Radhe; Titt, Uwe

    2015-01-01

    Purpose: The motivation of this study was to find and eliminate the cause of errors in dose-averaged linear energy transfer (LET) calculations from therapeutic protons in small targets, such as biological cell layers, calculated using the geant 4 Monte Carlo code. Furthermore, the purpose was also to provide a recommendation to select an appropriate LET quantity from geant 4 simulations to correlate with biological effectiveness of therapeutic protons. Methods: The authors developed a particle tracking step based strategy to calculate the average LET quantities (track-averaged LET, LETt and dose-averaged LET, LETd) using geant 4 for different tracking step size limits. A step size limit refers to the maximally allowable tracking step length. The authors investigated how the tracking step size limit influenced the calculated LETt and LETd of protons with six different step limits ranging from 1 to 500 μm in a water phantom irradiated by a 79.7-MeV clinical proton beam. In addition, the authors analyzed the detailed stochastic energy deposition information including fluence spectra and dose spectra of the energy-deposition-per-step of protons. As a reference, the authors also calculated the averaged LET and analyzed the LET spectra combining the Monte Carlo method and the deterministic method. Relative biological effectiveness (RBE) calculations were performed to illustrate the impact of different LET calculation methods on the RBE-weighted dose. Results: Simulation results showed that the step limit effect was small for LETt but significant for LETd. This resulted from differences in the energy-deposition-per-step between the fluence spectra and dose spectra at different depths in the phantom. Using the Monte Carlo particle tracking method in geant 4 can result in incorrect LETd calculation results in the dose plateau region for small step limits. The erroneous LETd results can be attributed to the algorithm to determine fluctuations in energy deposition along the

  9. Development and validation of RAYDOSE: a Geant4-based application for molecular radiotherapy

    NASA Astrophysics Data System (ADS)

    Marcatili, S.; Pettinato, C.; Daniels, S.; Lewis, G.; Edwards, P.; Fanti, S.; Spezi, E.

    2013-04-01

    We developed and validated a Monte-Carlo-based application (RAYDOSE) to generate patient-specific 3D dose maps on the basis of pre-treatment imaging studies. A CT DICOM image is used to model patient geometry, while repeated PET scans are employed to assess radionuclide kinetics and distribution at the voxel level. In this work, we describe the structure of this application and present the tests performed to validate it against reference data and experiments. We used the spheres of a NEMA phantom to calculate S values and total doses. The comparison with reference data from OLINDA/EXM showed an agreement within 2% for a sphere size above 2.8 cm diameter. A custom heterogeneous phantom composed of several layers of Perspex and lung equivalent material was used to compare TLD measurements of gamma radiation from 131I to Monte Carlo simulations. An agreement within 5% was found. RAYDOSE has been validated against reference data and experimental measurements and can be a useful multi-modality platform for treatment planning and research in MRT.

  10. Development and validation of RAYDOSE: a Geant4-based application for molecular radiotherapy.

    PubMed

    Marcatili, S; Pettinato, C; Daniels, S; Lewis, G; Edwards, P; Fanti, S; Spezi, E

    2013-04-21

    We developed and validated a Monte-Carlo-based application (RAYDOSE) to generate patient-specific 3D dose maps on the basis of pre-treatment imaging studies. A CT DICOM image is used to model patient geometry, while repeated PET scans are employed to assess radionuclide kinetics and distribution at the voxel level. In this work, we describe the structure of this application and present the tests performed to validate it against reference data and experiments. We used the spheres of a NEMA phantom to calculate S values and total doses. The comparison with reference data from OLINDA/EXM showed an agreement within 2% for a sphere size above 2.8 cm diameter. A custom heterogeneous phantom composed of several layers of Perspex and lung equivalent material was used to compare TLD measurements of gamma radiation from (131)I to Monte Carlo simulations. An agreement within 5% was found. RAYDOSE has been validated against reference data and experimental measurements and can be a useful multi-modality platform for treatment planning and research in MRT.

  11. Development of a Geant4 application to characterise a prototype neutron detector based on three orthogonal (3)He tubes inside an HDPE sphere.

    PubMed

    Gracanin, V; Guatelli, S; Prokopovich, D; Rosenfeld, A B; Berry, A

    2017-01-01

    The Bonner Sphere Spectrometer (BSS) system is a well-established technique for neutron dosimetry that involves detection of thermal neutrons within a range of hydrogenous moderators. BSS detectors are often used to perform neutron field surveys in order to determine the ambient dose equivalent H*(10) and estimate health risk to personnel. There is a potential limitation of existing neutron survey techniques, since some detectors do not consider the direction of the neutron field, which can result in overly conservative estimates of dose in neutron fields. This paper shows the development of a Geant4 simulation application to characterise a prototype neutron detector based on three orthogonal (3)He tubes inside a single HDPE sphere built at the Australian Nuclear Science and Technology Organisation (ANSTO). The Geant4 simulation has been validated with respect to experimental measurements performed with an Am-Be source. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

  12. Use of the GEANT4 Monte Carlo to determine three-dimensional dose factors for radionuclide dosimetry

    NASA Astrophysics Data System (ADS)

    Amato, Ernesto; Italiano, Antonio; Minutoli, Fabio; Baldari, Sergio

    2013-04-01

    The voxel-level dosimetry is the most simple and common approach to internal dosimetry of nonuniform distributions of activity within the human body. Aim of this work was to obtain the dose "S" factors (mGy/MBqs) at the voxel level for eight beta and beta-gamma emitting radionuclides commonly used in nuclear medicine diagnostic and therapeutic procedures. We developed a Monte Carlo simulation in GEANT4 of a region of soft tissue as defined by the ICRP, divided into 11×11×11 cubic voxels, 3 mm in side. The simulation used the parameterizations of the electromagnetic interaction optimized for low energy (EEDL, EPDL). The decay of each radionuclide (32P, 90Y, 99mTc, 177Lu, 131I, 153Sm, 186Re, 188Re) were simulated homogeneously distributed within the central voxel (0,0,0), and the energy deposited in the surrounding voxels was mediated on the 8 octants of the three dimensional space, for reasons of symmetry. The results obtained were compared with those available in the literature. While the iodine deviations remain within 16%, for phosphorus, a pure beta emitter, the agreement is very good for self-dose (0,0,0) and good for the dose to first neighbors, while differences are observed ranging from -60% to +100% for voxels far distant from the source. The existence of significant differences in the percentage calculation of the voxel S factors, especially for pure beta emitters such as 32P or 90Y, has already been highlighted by other authors. These data can usefully extend the dosimetric approach based on the voxel to other radionuclides not covered in the available literature.

  13. Comparisons of several transport models in their predictions in typical space radiation environments

    NASA Astrophysics Data System (ADS)

    Lin, Z. W.; Adams, J. H.; Barghouty, A. F.; Randeniya, S. D.; Tripathi, R. K.; Watts, J. W.; Yepes, P. P.

    2012-02-01

    We have used several transport codes to calculate dose and dose equivalent values as well as the particle spectra behind a slab or inside a spherical shell shielding in typical space radiation environments. Two deterministic codes, HZETRN and UPROP, and two Monte Carlo codes, FLUKA and Geant4, are included. A soft solar particle event, a hard solar particle event, and a solar minimum galactic cosmic rays environment are considered; and the shielding material is either aluminum or polyethylene. We find that the dose values and particle spectra from HZETRN are in general rather consistent with Geant4 except for neutrons. The dose equivalent values from HZETRN and Geant4 are not far from each other, but the HZETRN values behind shielding are often lower than the Geant4 values. Results from FLUKA and Geant4 are mostly consistent for considered cases. However, results from the legacy code UPROP are often quite different from the other transport codes, partly due to its non-consideration of neutrons. Comparisons for the spherical shell geometry exhibit the same qualitative features as for the slab geometry. In addition, results from both deterministic and Monte Carlo transport codes show that the dose equivalent inside the spherical shell decreases from the center to the inner surface and this decrease is large for solar particle events; consistent with an earlier study based on deterministic radiation transport results. This study demonstrates both the consistency and inconsistency among these transport models in their typical space radiation predictions; further studies will be required to pinpoint the exact physics modules in these models that cause the differences and thus may be improved.

  14. The investigation of prostatic calcifications using μ-PIXE analysis and their dosimetric effect in low dose rate brachytherapy treatments using Geant4

    NASA Astrophysics Data System (ADS)

    Pope, D. J.; Cutajar, D. L.; George, S. P.; Guatelli, S.; Bucci, J. A.; Enari, K. E.; Miller, S.; Siegele, R.; Rosenfeld, A. B.

    2015-06-01

    Low dose rate brachytherapy is a widely used modality for the treatment of prostate cancer. Most clinical treatment planning systems currently in use approximate all tissue to water, neglecting the existence of inhomogeneities, such as calcifications. The presence of prostatic calcifications may perturb the dose due to the higher photoelectric effect cross section in comparison to water. This study quantitatively evaluates the effect of prostatic calcifications on the dosimetric outcome of brachytherapy treatments by means of Monte Carlo simulations and its potential clinical consequences. Four pathological calcification samples were characterised with micro-particle induced x-ray emission (μ-PIXE) to determine their heavy elemental composition. Calcium, phosphorus and zinc were found to be the predominant heavy elements in the calcification composition. Four clinical patient brachytherapy treatments were modelled using Geant4 based Monte Carlo simulations, in terms of the distribution of brachytherapy seeds and calcifications in the prostate. Dose reductions were observed to be up to 30% locally to the calcification boundary, calcification size dependent. Single large calcifications and closely placed calculi caused local dose reductions of between 30-60%. Individual calculi smaller than 0.5 mm in diameter showed minimal dosimetric impact, however, the effects of small or diffuse calcifications within the prostatic tissue could not be determined using the methods employed in the study. The simulation study showed a varying reduction on common dosimetric parameters. D90 showed a reduction of 2-5%, regardless of calcification surface area and volume. The parameters V100, V150 and V200 were also reduced by as much as 3% and on average by 1%. These reductions were also found to relate to the surface area and volume of calcifications, which may have a significant dosimetric impact on brachytherapy treatment, however, such impacts depend strongly on specific factors

  15. Development of a randomized 3D cell model for Monte Carlo microdosimetry simulations

    SciTech Connect

    Douglass, Michael; Bezak, Eva; Penfold, Scott

    2012-06-15

    Purpose: The objective of the current work was to develop an algorithm for growing a macroscopic tumor volume from individual randomized quasi-realistic cells. The major physical and chemical components of the cell need to be modeled. It is intended to import the tumor volume into GEANT4 (and potentially other Monte Carlo packages) to simulate ionization events within the cell regions. Methods: A MATLAB Copyright-Sign code was developed to produce a tumor coordinate system consisting of individual ellipsoidal cells randomized in their spatial coordinates, sizes, and rotations. An eigenvalue method using a mathematical equation to represent individual cells was used to detect overlapping cells. GEANT4 code was then developed to import the coordinate system into GEANT4 and populate it with individual cells of varying sizes and composed of the membrane, cytoplasm, reticulum, nucleus, and nucleolus. Each region is composed of chemically realistic materials. Results: The in-house developed MATLAB Copyright-Sign code was able to grow semi-realistic cell distributions ({approx}2 Multiplication-Sign 10{sup 8} cells in 1 cm{sup 3}) in under 36 h. The cell distribution can be used in any number of Monte Carlo particle tracking toolkits including GEANT4, which has been demonstrated in this work. Conclusions: Using the cell distribution and GEANT4, the authors were able to simulate ionization events in the individual cell components resulting from 80 keV gamma radiation (the code is applicable to other particles and a wide range of energies). This virtual microdosimetry tool will allow for a more complete picture of cell damage to be developed.

  16. Physical modelling in biomechanics.

    PubMed Central

    Koehl, M A R

    2003-01-01

    Physical models, like mathematical models, are useful tools in biomechanical research. Physical models enable investigators to explore parameter space in a way that is not possible using a comparative approach with living organisms: parameters can be varied one at a time to measure the performance consequences of each, while values and combinations not found in nature can be tested. Experiments using physical models in the laboratory or field can circumvent problems posed by uncooperative or endangered organisms. Physical models also permit some aspects of the biomechanical performance of extinct organisms to be measured. Use of properly scaled physical models allows detailed physical measurements to be made for organisms that are too small or fast to be easily studied directly. The process of physical modelling and the advantages and limitations of this approach are illustrated using examples from our research on hydrodynamic forces on sessile organisms, mechanics of hydraulic skeletons, food capture by zooplankton and odour interception by olfactory antennules. PMID:14561350

  17. Analysis of the track- and dose-averaged LET and LET spectra in proton therapy using the GEANT4 Monte Carlo code

    SciTech Connect

    Guan, Fada; Peeler, Christopher; Taleei, Reza; Randeniya, Sharmalee; Ge, Shuaiping; Mirkovic, Dragan; Mohan, Radhe; Titt, Uwe; Bronk, Lawrence; Geng, Changran; Grosshans, David

    2015-11-15

    Purpose: The motivation of this study was to find and eliminate the cause of errors in dose-averaged linear energy transfer (LET) calculations from therapeutic protons in small targets, such as biological cell layers, calculated using the GEANT 4 Monte Carlo code. Furthermore, the purpose was also to provide a recommendation to select an appropriate LET quantity from GEANT 4 simulations to correlate with biological effectiveness of therapeutic protons. Methods: The authors developed a particle tracking step based strategy to calculate the average LET quantities (track-averaged LET, LET{sub t} and dose-averaged LET, LET{sub d}) using GEANT 4 for different tracking step size limits. A step size limit refers to the maximally allowable tracking step length. The authors investigated how the tracking step size limit influenced the calculated LET{sub t} and LET{sub d} of protons with six different step limits ranging from 1 to 500 μm in a water phantom irradiated by a 79.7-MeV clinical proton beam. In addition, the authors analyzed the detailed stochastic energy deposition information including fluence spectra and dose spectra of the energy-deposition-per-step of protons. As a reference, the authors also calculated the averaged LET and analyzed the LET spectra combining the Monte Carlo method and the deterministic method. Relative biological effectiveness (RBE) calculations were performed to illustrate the impact of different LET calculation methods on the RBE-weighted dose. Results: Simulation results showed that the step limit effect was small for LET{sub t} but significant for LET{sub d}. This resulted from differences in the energy-deposition-per-step between the fluence spectra and dose spectra at different depths in the phantom. Using the Monte Carlo particle tracking method in GEANT 4 can result in incorrect LET{sub d} calculation results in the dose plateau region for small step limits. The erroneous LET{sub d} results can be attributed to the algorithm to

  18. The Cryogenic AntiCoincidence Detector for the ATHENA X-IFU: Design Aspects by Geant4 Simulation and Preliminary Characterization of the New Single Pixel

    NASA Astrophysics Data System (ADS)

    Macculi, C.; Argan, A.; D'Andrea, M.; Lotti, S.; Piro, L.; Biasotti, M.; Corsini, D.; Gatti, F.; Orlando, A.; Torrioli, G.

    2016-08-01

    The ATHENA observatory is the second large-class ESA mission, in the context of the Cosmic Vision 2015-2025, scheduled to be launched on 2028 at L2 orbit. One of the two planned focal plane instruments is the X-ray Integral Field Unit (X-IFU), which will be able to perform simultaneous high-grade energy spectroscopy and imaging over the 5 arcmin FoV by means of a kilo-pixel array of transition-edge sensor (TES) microcalorimeters, coupled to a high-quality X-ray optics. The X-IFU sensitivity is degraded by the particle background, induced by primary protons of both solar and cosmic rays' origin and secondary electrons. A Cryogenic AntiCoincidence (CryoAC) TES-based detector, located <1 mm below the TES array, will allow the mission to reach the background level that enables its scientific goals. The CryoAC is a 4-pixel detector made of Silicon absorbers sensed by Iridium TESs. We currently achieve a TRL = 3-4 at the single-pixel level. We have designed and developed two further prototypes in order to reach TRL = 4. The design of the CryoAC has been also optimized using the Geant4 simulation tool. Here we will describe some results from the Geant4 simulations performed to optimize the design and preliminary test results from the first of the two detectors, 1 cm2 area, made of 65 Ir TESs.

  19. Influence of the geometrical detail in the description of DNA and the scoring method of ionization clustering on nanodosimetric parameters of track structure: a Monte Carlo study using Geant4-DNA

    NASA Astrophysics Data System (ADS)

    Bueno, M.; Schulte, R.; Meylan, S.; Villagrasa, C.

    2015-11-01

    The aim of this study was to evaluate the influence of the geometrical detail of the DNA on nanodosimetric parameters of track structure induced by protons and alpha particles of different energies (LET values ranging from 1 to 162.5~\\text{keV}~μ {{\\text{m}}-1} ) as calculated by Geant4-DNA Monte Carlo simulations. The first geometry considered consisted of a well-structured placement of a realistic description of the DNA double helix wrapped around cylindrical histones (GeomHist) forming a 18 kbp-long chromatin fiber. In the second geometry considered, the DNA was modeled as a total of 1800 ten bp-long homogeneous cylinders (2.3 nm diameter and 3.4 nm height) placed in random positions and orientations (GeomCyl). As for GeomHist, GeomCyl contained a DNA material equivalent to 18 kbp. Geant4-DNA track structure simulations were performed and ionizations were counted in the scoring volumes. For GeomCyl, clusters were defined as the number of ionizations (ν) scored in each 10 bp-long cylinder. For GeomHist, clusters of ionizations scored in the sugar-phosphate groups of the double-helix were revealed by the DBSCAN clustering algorithm according to a proximity criteria among ionizations separated by less than 10 bp. The topology of the ionization clusters formed using GeomHist and GeomCyl geometries were compared in terms of biologically relevant nanodosimetric quantities. The discontinuous modeling of the DNA for GeomCyl led to smaller cluster sizes than for GeomHist. The continuous modeling of the DNA molecule for GeomHist allowed the merging of ionization points by the DBSCAN algorithm giving rise to larger clusters, which were not detectable within the GeomCyl geometry. Mean cluster size (m1) was found to be of the order of 10% higher for GeomHist compared to GeomCyl for LET <15~\\text{keV}~μ {{\\text{m}}-1} . For higher LETs, the difference increased with LET similarly for protons and alpha particles. Both geometries showed the same relationship

  20. A comparison of MCNP6-1.0 and GEANT 4-10.1 when evaluating the neutron output of a complex real world nuclear environment: The thermal neutron facility at the Tri Universities Meson facility

    NASA Astrophysics Data System (ADS)

    Monk, S. D.; Shippen, B. A.; Colling, B. R.; Cheneler, D.; Al Hamrashdi, H.; Alton, T.

    2017-05-01

    A comparison of the Monte Carlo based simulation codes MCNP6-1.0 and GEANT4-10.1 as used for modelling large scale structures is presented here. The high-energy neutron field at the Tri Universities Meson Facility (TRIUMF) in Vancouver, British Columbia is the structure modelled in this work. Work with the emphasis on the modelling of the facility and comparing with experimental results has been published previously, whereas this work is focussed on comparing the performance of the codes over relatively high depths of material rather than the accuracy of the results themselves in comparison to experimental data. Comparisons of three different locations within the neutron facility are modelled and presented using both codes as well as analysis of the transport of typical neutrons fields through large blocks of iron, water, lead and aluminium in order to determine where any deviations are likely to have occurred. Results indicate that over short distances, results from the two codes are in broad agreement - although over greater distances and within more complex geometries, deviation increases dramatically. The conclusions reached are that it is likely the deviations between the codes is caused by both the compounding effect of slight differences between the cross section files used by the two codes to determine the neutron transport through iron, and differences in the processes used by both codes.

  1. Monte Carlo simulation of a PhosWatch detector using Geant4 for xenon isotope beta-gamma coincidence spectrum profile and detection efficiency calculations.

    PubMed

    Mekarski, P; Zhang, W; Ungar, K; Bean, M; Korpach, E

    2009-10-01

    A simulation tool has been developed using the Geant4 Toolkit to simulate a PhosWatch single channel beta-gamma coincidence detection system consisting of a CsI(Tl)/BC404 Phoswich well detector and pulse shape analysis algorithms implemented digital signal processor. The tool can be used to simulate the detector's response for all the gamma rays and beta particles emitted from (135)Xe, (133m)Xe, (133)Xe, (131m)Xe and (214)Pb. Two- and three-dimensional beta-gamma coincidence spectra from the PhosWatch detector can be produced using the simulation tool. The accurately simulated spectra could be used to calculate system coincidence detection efficiency for each xenon isotope, the corrections for the interference from the various spectral components from radon and xenon isotopes, and system gain calibration. Also, it can generate two- and three-dimensional xenon reference spectra to test beta-gamma coincidence spectral deconvolution analysis software.

  2. Determination of the Thickness of the Back Dead-Layer of GRETINA Crystals via Comparisons of Measured Photopeak Efficiencies with GEANT4 Simulations

    NASA Astrophysics Data System (ADS)

    Jarvis, L. R.; Stine, C. G.; Riley, L. A.

    2016-09-01

    Measurements of the photopeak efficiency of the GRETINA array up to 3.5 MeV made at the National Superconducting Cyclotron Laboratory with 152Eu and 56Co sources were compared with GEANT 4 simulations. We developed a method of determining the average thickness of the back dead layers of the GRETINA crystals by considering the partial photopeak efficiencies of events including gamma-ray interactions in the back slice of the crystals. The impact of dead-layer thicknesses on the accuracy of simulated photopeak efficiencies and the ratio of photopeak counts measured in the two GRETINA crystal types is discussed. This work was supported by the National Science Foundation under Grant Nos. PHY-1303480 and PHY-1102511 and by the US Department of Energy under Grant No. DE-AC02-05CH11231.

  3. Simulation, optimization and testing of a novel high spatial resolution X-ray imager based on Zinc Oxide nanowires in Anodic Aluminium Oxide membrane using Geant4

    NASA Astrophysics Data System (ADS)

    Esfandi, F.; Saramad, S.

    2015-07-01

    In this work, a new generation of scintillator based X-ray imagers based on ZnO nanowires in Anodized Aluminum Oxide (AAO) nanoporous template is characterized. The optical response of ordered ZnO nanowire arrays in porous AAO template under low energy X-ray illumination is simulated by the Geant4 Monte Carlo code and compared with experimental results. The results show that for 10 keV X-ray photons, by considering the light guiding properties of zinc oxide inside the AAO template and suitable selection of detector thickness and pore diameter, the spatial resolution less than one micrometer and the detector detection efficiency of 66% are accessible. This novel nano scintillator detector can have many advantages for medical applications in the future.

  4. Efficiency calibration and coincidence summing correction for a large volume (946cm(3)) LaBr3(Ce) detector: GEANT4 simulations and experimental measurements.

    PubMed

    Dhibar, M; Mankad, D; Mazumdar, I; Kumar, G Anil

    2016-12-01

    The paper describes the studies on efficiency calibration and coincidence summing correction for a 3.5″×6″ cylindrical LaBr3(Ce)detector. GEANT4 simulations were made with point sources, namely, (60)Co, (94)Nb, (24)Na, (46)Sc and (22)Na. The simulated efficiencies, extracted using (60)Co, (94)Nb, (24)Na and (46)Sc that emit coincident gamma rays with same decay intensities, were corrected for coincidence summing by applying the method proposed by Vidmar et al. (2003). The method was applied, for the first time, for correcting the simulated efficiencies extracted using (22)Na that emits coincident gamma rays with different decay intensities. The measured results obtained using (60)Co and (22)Na were found to be in good agreement with simulated results. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Dosimetric impact assessment using a general algorithm in geant4 simulations for a complex-shaped multileaf collimator.

    PubMed

    Perales, Á; Cortés-Giraldo, M A; Miras, H; Arráns, R; Gallardo, M I

    2017-09-01

    We have developed an inhouse algorithm for the multileaf collimator (MLC) geometry model construction with an appropriate accuracy for dosimetric tests. Our purpose is to build a complex type of MLC and analyze the influence of the modeling parameters on the dose calculation. Using radiochromic films as detector the following tests were done: (I) Density test field: to compare measured and calculated dose distributions in order to determine the tungsten alloy physical density value. (II) Leaf ends test field: to verify the penumbra shape sensitivity against the discretization level set to simulate the curved leaf ends. (III) MLC-closed field: to obtain the value of the air gap between opposite leaves for a closed configuration which completes the modeling of the MLC leakage radiation. (IV) Picket-fence field: to fit the leaf tilt angle with respect of the divergent ray emerging from the source. For a 18.5g/cm(3) density value we have obtained a maximum, minimum and mean leakage values of 0.43%, 0.36% and 0.38%, similar to the experimental ones. The best discretization level in the leaf ends field shows a 5.51mm FWHM, very close to the measured value (5.49mm). An air gap of 370μm has been used in the simulation for the separation between opposite leaves. Using a 0.44° tilt angle, we found the same pattern as the experimental values. Our code can reproduce complex MLC designs with a submilimetric dosimetric accuracy which implies the necessary background for dose calculation of high clinical interest small fields. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  6. Beyond Standard Model Physics

    SciTech Connect

    Bellantoni, L.

    2009-11-01

    There are many recent results from searches for fundamental new physics using the TeVatron, the SLAC b-factory and HERA. This talk quickly reviewed searches for pair-produced stop, for gauge-mediated SUSY breaking, for Higgs bosons in the MSSM and NMSSM models, for leptoquarks, and v-hadrons. There is a SUSY model which accommodates the recent astrophysical experimental results that suggest that dark matter annihilation is occurring in the center of our galaxy, and a relevant experimental result. Finally, model-independent searches at D0, CDF, and H1 are discussed.

  7. Simulating cosmic radiation absorption and secondary particle production of solar panel layers of Low Earth Orbit (LEO) satellite with GEANT4

    NASA Astrophysics Data System (ADS)

    Yiǧitoǧlu, Merve; Veske, Doǧa; Nilüfer Öztürk, Zeynep; Bilge Demirköz, Melahat

    2016-07-01

    All devices which operate in space are exposed to cosmic rays during their operation. The resulting radiation may cause fatal damages in the solid structure of devices and the amount of absorbed radiation dose and secondary particle production for each component should be calculated carefully before the production. Solar panels are semiconductor solid state devices and are very sensitive to radiation. Even a short term power cut-off may yield a total failure of the satellite. Even little doses of radiation can change the characteristics of solar cells. This deviation can be caused by rarer high energetic particles as well as the total ionizing dose from the abundant low energy particles. In this study, solar panels planned for a specific LEO satellite, IMECE, are analyzed layer by layer. The Space Environment Information System (SPENVIS) database and GEANT4 simulation software are used to simulate the layers of the panels. The results obtained from the simulation will be taken in account to determine the amount of radiation protection and resistance needed for the panels or to revise the design of the panels.

  8. NOTE: Biological dose calculation with Monte Carlo physics simulation for heavy-ion radiotherapy

    NASA Astrophysics Data System (ADS)

    Kase, Yuki; Kanematsu, Nobuyuki; Kanai, Tatsuaki; Matsufuji, Naruhiro

    2006-12-01

    Treatment planning of heavy-ion radiotherapy involves predictive calculation of not only the physical dose but also the biological dose in a patient body. The biological dose is defined as the product of the physical dose and the relative biological effectiveness (RBE). In carbon-ion radiotherapy at National Institute of Radiological Sciences, the RBE value has been defined as the ratio of the 10% survival dose of 200 kVp x-rays to that of the radiation of interest for in vitro human salivary gland tumour cells. In this note, the physical and biological dose distributions of a typical therapeutic carbon-ion beam are calculated using the GEANT4 Monte Carlo simulation toolkit in comparison with those with the biological dose estimate system based on the one-dimensional beam model currently used in treatment planning. The results differed between the GEANT4 simulation and the one-dimensional beam model, indicating the physical limitations in the beam model. This study demonstrates that the Monte Carlo physics simulation technique can be applied to improve the accuracy of the biological dose distribution in treatment planning of heavy-ion radiotherapy.

  9. Physical models of cognition

    NASA Astrophysics Data System (ADS)

    Zak, Michail

    1994-05-01

    This paper presents and discusses physical models for simulating some aspects of neural intelligence, and, in particular, the process of cognition. The main departure from the classical approach here is in utilization of a terminal version of classical dynamics introduced by the author earlier. Based upon violations of the Lipschitz condition at equilibrium points, terminal dynamics attains two new fundamental properties: it is spontaneous and nondeterministic. Special attention is focused on terminal neurodynamics as a particular architecture of terminal dynamics which is suitable for modeling of information flows. Terminal neurodynamics possesses a well-organized probabilistic structure which can be analytically predicted, prescribed, and controlled, and therefore which presents a powerful tool for modeling real-life uncertainties. Two basic phenomena associated with random behavior of neurodynamic solutions are exploited. The first one is a stochastic attractor—a stable stationary stochastic process to which random solutions of a closed system converge. As a model of the cognition process, a stochastic attractor can be viewed as a universal tool for generalization and formation of classes of patterns. The concept of stochastic attractor is applied to model a collective brain paradigm explaining coordination between simple units of intelligence which perform a collective task without direct exchange of information. The second fundamental phenomenon discussed is terminal chaos which occurs in open systems. Applications of terminal chaos to information fusion as well as to explanation and modeling of coordination among neurons in biological systems are discussed. It should be emphasized that all the models of terminal neurodynamics are implementable in analog devices, which means that all the cognition processes discussed in the paper are reducible to the laws of Newtonian mechanics.

  10. Physical Models of Cognition

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1994-01-01

    This paper presents and discusses physical models for simulating some aspects of neural intelligence, and, in particular, the process of cognition. The main departure from the classical approach here is in utilization of a terminal version of classical dynamics introduced by the author earlier. Based upon violations of the Lipschitz condition at equilibrium points, terminal dynamics attains two new fundamental properties: it is spontaneous and nondeterministic. Special attention is focused on terminal neurodynamics as a particular architecture of terminal dynamics which is suitable for modeling of information flows. Terminal neurodynamics possesses a well-organized probabilistic structure which can be analytically predicted, prescribed, and controlled, and therefore which presents a powerful tool for modeling real-life uncertainties. Two basic phenomena associated with random behavior of neurodynamic solutions are exploited. The first one is a stochastic attractor ; a stable stationary stochastic process to which random solutions of a closed system converge. As a model of the cognition process, a stochastic attractor can be viewed as a universal tool for generalization and formation of classes of patterns. The concept of stochastic attractor is applied to model a collective brain paradigm explaining coordination between simple units of intelligence which perform a collective task without direct exchange of information. The second fundamental phenomenon discussed is terminal chaos which occurs in open systems. Applications of terminal chaos to information fusion as well as to explanation and modeling of coordination among neurons in biological systems are discussed. It should be emphasized that all the models of terminal neurodynamics are implementable in analog devices, which means that all the cognition processes discussed in the paper are reducible to the laws of Newtonian mechanics.

  11. Physical Models of Cognition

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1994-01-01

    This paper presents and discusses physical models for simulating some aspects of neural intelligence, and, in particular, the process of cognition. The main departure from the classical approach here is in utilization of a terminal version of classical dynamics introduced by the author earlier. Based upon violations of the Lipschitz condition at equilibrium points, terminal dynamics attains two new fundamental properties: it is spontaneous and nondeterministic. Special attention is focused on terminal neurodynamics as a particular architecture of terminal dynamics which is suitable for modeling of information flows. Terminal neurodynamics possesses a well-organized probabilistic structure which can be analytically predicted, prescribed, and controlled, and therefore which presents a powerful tool for modeling real-life uncertainties. Two basic phenomena associated with random behavior of neurodynamic solutions are exploited. The first one is a stochastic attractor ; a stable stationary stochastic process to which random solutions of a closed system converge. As a model of the cognition process, a stochastic attractor can be viewed as a universal tool for generalization and formation of classes of patterns. The concept of stochastic attractor is applied to model a collective brain paradigm explaining coordination between simple units of intelligence which perform a collective task without direct exchange of information. The second fundamental phenomenon discussed is terminal chaos which occurs in open systems. Applications of terminal chaos to information fusion as well as to explanation and modeling of coordination among neurons in biological systems are discussed. It should be emphasized that all the models of terminal neurodynamics are implementable in analog devices, which means that all the cognition processes discussed in the paper are reducible to the laws of Newtonian mechanics.

  12. SU-E-T-290: Secondary Dose Monitoring Using Scintillating Fibers in Proton Therapy of Prostate Cancer: A Geant4 Monte Carlo Simulation

    SciTech Connect

    Tesfamicael, B; Gueye, P; Lyons, D; Avery, S; Mahesh, M

    2014-06-01

    Purpose: To monitor the secondary dose distribution originating from a water phantom during proton therapy of prostate cancer using scintillating fibers. Methods: The Geant4 Monte Carlo toolkit version 9.6.p02 was used to simulate prostate cancer proton therapy based treatments. Two cases were studied. In the first case, 8 × 8 = 64 equally spaced fibers inside three 4 × 4 × 2.54 cmm{sup 3} DuPont™ Delrin blocks were used to monitor the emission of secondary particles in the transverse (left and right) and distal regions relative to the beam direction. In the second case, a scintillating block with a thickness of 2.54 cm and equal vertical and longitudinal dimensions as the water phantom was used. Geometrical cuts were used to extract the energy deposited in each fiber and the scintillating block. Results: The transverse dose distributions from secondary particles in both cases agree within <5% and with a very good symmetry. The energy deposited not only gradually increases as one moves from the peripheral row fibers towards the center of the block (aligned with the center of the prostate) but also decreases as one goes from the frontal to distal region of the block. The ratio of the doses from the prostate to the ones in the middle two rows of fibers showed a linear relationship with a slope (−3.55±2.26) × 10−5 MeV per treatment Gy. The distal detectors recorded a very small energy deposited due to water attenuation. Conclusion: With a good calibration and the ability to define a good correlation between the dose to the external fibers and the prostate, such fibers can be used for real time dose verification to the target.

  13. Efficiency corrections in determining the (137)Cs inventory of environmental soil samples by using relative measurement method and GEANT4 simulations.

    PubMed

    Li, Gang; Liang, Yongfei; Xu, Jiayun; Bai, Lixin

    2015-08-01

    The determination of (137)Cs inventory is widely used to estimate the soil erosion or deposition rate. The generally used method to determine the activity of volumetric samples is the relative measurement method, which employs a calibration standard sample with accurately known activity. This method has great advantages in accuracy and operation only when there is a small difference in elemental composition, sample density and geometry between measuring samples and the calibration standard. Otherwise it needs additional efficiency corrections in the calculating process. The Monte Carlo simulations can handle these correction problems easily with lower financial cost and higher accuracy. This work presents a detailed description to the simulation and calibration procedure for a conventionally used commercial P-type coaxial HPGe detector with cylindrical sample geometry. The effects of sample elemental composition, density and geometry were discussed in detail and calculated in terms of efficiency correction factors. The effect of sample placement was also analyzed, the results indicate that the radioactive nuclides and sample density are not absolutely uniform distributed along the axial direction. At last, a unified binary quadratic functional relationship of efficiency correction factors as a function of sample density and height was obtained by the least square fitting method. This function covers the sample density and height range of 0.8-1.8 g/cm(3) and 3.0-7.25 cm, respectively. The efficiency correction factors calculated by the fitted function are in good agreement with those obtained by the GEANT4 simulations with the determination coefficient value greater than 0.9999. The results obtained in this paper make the above-mentioned relative measurements more accurate and efficient in the routine radioactive analysis of environmental cylindrical soil samples.

  14. Evaluation of the dose perturbation around gold and steel fiducial markers in a medical linac through Geant4 Monte Carlo simulation.

    PubMed

    Pontoriero, Antonio; Amato, Ernesto; Iatí, Giuseppe; De Renzis, Costantino; Pergolizzi, Stefano

    2015-01-01

    Purpose of this work was to study the dose perturbation within the target volume of a external MV radiation therapy when using metal fiducials. We developed a Monte Carlo simulation in Geant4 of a cylindrical fiducial made either of gold or of steel and simulated the photon irradiation beam originating from a medical Linac operating at 6, 10 or 15 MV. For each energy, two different irradiation schemes were simulated: a single 5 × 5-cm square field in the -x direction, and five 5 × 5-cm fields at 0°, 80°, 165°, 195° and 280°. In a single beam irradiation scheme, we observed a dose reduction behind fiducials varying from -20% for gold at 6 MV to -5% for steel at 15 MV, and a dose increment in front of the fiducial ranging from +33% for gold at 15 MV to +10% for steel at 6 MV. When five beams were employed, a dose increment ranging from +28% to +46% has been found around gold. Around a steel fiducial, an average increment of +17% was found, irrespective of the photon energy. When using a single beam, the decrement of dose behind both steel and gold markers increases with the photon energy. This effect vanishes when a multifield treatment is delivered; in this instance there is a dose increment around fiducials, according to both fiducial material and photon energy, with lower values for steel and 6 MV. This energy represents the best choice when fiducial markers are present inside the irradiated volume.

  15. Validation of GEANT4 simulations for percentage depth dose calculations in heterogeneous media by using small photon beams from the 6-MV Cyberknife: Comparison with photon beam dosimetry with EBT2 film

    NASA Astrophysics Data System (ADS)

    Lee, Chung Il; Yoon, Sei-Chul; Shin, Jae Won; Hong, Seung-Woo; Suh, Tae Suk; Min, Kyung Joo; Lee, Sang Deok; Chung, Su Mi; Jung, Jae-Yong

    2015-04-01

    Percentage depth dose (PDD) distributions in heterogeneous phantoms with lung and soft bone equivalent media are studied by using the GEANT4 Monte Carlo code. For lung equivalent media, Balsa wood is used, and for soft bone equivalent media, a compound material with epoxy resin, hardener and calcium carbonate is used. Polystyrene slabs put together with these materials are used as a heterogeneous phantom. Dose measurements are performed with Gafchromic EBT2 film by using photon beams from the 6-MV CyberKnife at the Seoul Uridul Hospital. The cone sizes of the photon beams are varied from 5 to 10 to 30 mm. When the Balsa wood is inserted in the phantom, the dose measured with EBT2 film is found to be significantly different from the dose without the EBT2 film in and the dose beyond the Balsa wood region, particularly for small field sizes. On the other hand, when the soft bone equivalent material is inserted in the phantom, the discrepancy between the dose measured with EBT2 film and the dose without EBT2 film can be seen only in the region of the soft bone equivalent material. GEANT4 simulations are done with and without the EBT2 film to compare the simulation results with measurements. The GEANT4 simulations including EBT2 film are found to agree well with the measurements for all the cases within an error of 2.2%. The results of the present study show that GEANT4 gives reasonable results for the PDD calculations in heterogeneous media when using photon beams produced by the 6-MV CyberKnife

  16. MODELING PHYSICAL HABITAT PARAMETERS

    EPA Science Inventory

    Salmonid populations can be affected by alterations in stream physical habitat. Fish productivity is determined by the stream's physical habitat structure ( channel form, substrate distribution, riparian vegetation), water quality, flow regime and inputs from the watershed (sedim...

  17. MODELING PHYSICAL HABITAT PARAMETERS

    EPA Science Inventory

    Salmonid populations can be affected by alterations in stream physical habitat. Fish productivity is determined by the stream's physical habitat structure ( channel form, substrate distribution, riparian vegetation), water quality, flow regime and inputs from the watershed (sedim...

  18. Evolutionary Industrial Physical Model Generation

    NASA Astrophysics Data System (ADS)

    Carrascal, Alberto; Alberdi, Amaia

    Both complexity and lack of knowledge associated to physical processes makes physical models design an arduous task. Frequently, the only available information about the physical processes are the heuristic data obtained from experiments or at best a rough idea on what are the physical principles and laws that underlie considered physical processes. Then the problem is converted to find a mathematical expression which fits data. There exist traditional approaches to tackle the inductive model search process from data, such as regression, interpolation, finite element method, etc. Nevertheless, these methods either are only able to solve a reduced number of simple model typologies, or the given black-box solution does not contribute to clarify the analyzed physical process. In this paper a hybrid evolutionary approach to search complex physical models is proposed. Tests carried out on a real-world industrial physical process (abrasive water jet machining) demonstrate the validity of this approach.

  19. Building Mental Models by Dissecting Physical Models

    ERIC Educational Resources Information Center

    Srivastava, Anveshna

    2016-01-01

    When students build physical models from prefabricated components to learn about model systems, there is an implicit trade-off between the physical degrees of freedom in building the model and the intensity of instructor supervision needed. Models that are too flexible, permitting multiple possible constructions require greater supervision to…

  20. Building Mental Models by Dissecting Physical Models

    ERIC Educational Resources Information Center

    Srivastava, Anveshna

    2016-01-01

    When students build physical models from prefabricated components to learn about model systems, there is an implicit trade-off between the physical degrees of freedom in building the model and the intensity of instructor supervision needed. Models that are too flexible, permitting multiple possible constructions require greater supervision to…

  1. TH-A-19A-05: Modeling Physics Properties and Biologic Effects Induced by Proton and Helium Ions

    SciTech Connect

    Taleei, R; Titt, U; Peeler, C; Guan, F; Mirkovic, D; Grosshans, D; Mohan, R

    2014-06-15

    Purpose: Currently, proton and carbon ions are used for cancer treatment. More recently, other light ions including helium ions have shown interesting physical and biological properties. The purpose of this work is to study the biological and physical properties of helium ions (He-3) in comparison to protons. Methods: Monte Carlo simulations with FLUKA, GEANT4 and MCNPX were used to calculate proton and He-3 dose distributions in water phantoms. The energy spectra of proton and He-3 beams were calculated with high resolution for use in biological models. The repair-misrepairfixation (RMF) model was subsequently used to calculate the RBE. Results: The proton Bragg curve calculations show good agreement between the three general purpose Monte Carlo codes. In contrast, the He-3 Bragg curve calculations show disagreement (for the magnitude of the Bragg peak) between FLUKA and the other two Monte Carlo codes. The differences in the magnitude of the Bragg peak are mainly due to the discrepancy in the secondary fragmentation cross sections used by the codes. The RBE for V79 cell lines is about 0.96 and 0.98 at the entrance of proton and He-3 ions depth dose respectively. The RBE increases to 1.06 and 1.59 at the Bragg peak of proton and He-3 ions. The results demonstrated that LET, microdosimetric parameters (such as dose-mean lineal energy) and RBE are nearly constant along the plateau region of Bragg curve, while all parameters increase within the Bragg peak and at the distal edge for both proton and He-3 ions. Conclusion: The Monte Carlo codes should revise the fragmentation cross sections to more accurately simulate the physical properties of He-3 ions. The increase in RBE for He-3 ions is higher than for proton beams at the Bragg peak.

  2. Modeling Physical Objects

    DTIC Science & Technology

    1990-10-01

    of the conference will be published by Oxford University Press . At the ASME Conference on Design Automation in Chicago. D. Dmtta and I presented... University Press , 1991. .1. Jung-Hong (’huang, "Surface Approximations in Geometric Modeling," PhD Diss., Dept. of ComIp. Sci., Purdue University: Rept. CER-90-37. September 1990. 3 ...utoination. Chicago, 1990: (with D. Dutta). 3. "How to Construct the Skeleton of CSG Objects," Proc. ,Ith JA1A Con!. Math. of Suifaces. Oxford

  3. Physical model of kitesurfing

    NASA Astrophysics Data System (ADS)

    Zimoch, Pawel; Paxson, Adam; Obropta, Edward; Peleg, Tom; Parker, Sam; Hosoi, A. E.

    2013-11-01

    Kitesurfing is a popular water sport, similar to windsurfing, utilizing a surfboard-like platform pulled by a large kite operated by the surfer. While the kite generates thrust that propels the surfer across the water, much like a traditional sail, it is also capable of generating vertical forces on the surfer, reducing the hydrodynamic lift generated by the surfboard required to support the surfer's weight. This in turn reduces drag acting on the surfboard, making sailing possible in winds lower than required by other sailing sports. We describe aerodynamic and hydrodynamic models for the forces acting on the kite and the surfboard, and couple them while considering the kite's position in space and the requirement for the kite to support its own weight. We then use these models to quantitatively characterize the significance of the vertical force component generated by the kite on sailing performance (the magnitude of achievable steady-state velocities and the range of headings, relative to the true wind direction, in which sailing is possible), and the degradation in sailing performance with decreasing wind speeds. Finally, we identify the areas of kite and surfboard design whose development could have the greatest impact on improving sailing performance in low wind conditions.

  4. Physical Modeling of Microtubules Network

    NASA Astrophysics Data System (ADS)

    Allain, Pierre; Kervrann, Charles

    2014-10-01

    Microtubules (MT) are highly dynamic tubulin polymers that are involved in many cellular processes such as mitosis, intracellular cell organization and vesicular transport. Nevertheless, the modeling of cytoskeleton and MT dynamics based on physical properties is difficult to achieve. Using the Euler-Bernoulli beam theory, we propose to model the rigidity of microtubules on a physical basis using forces, mass and acceleration. In addition, we link microtubules growth and shrinkage to the presence of molecules (e.g. GTP-tubulin) in the cytosol. The overall model enables linking cytosol to microtubules dynamics in a constant state space thus allowing usage of data assimilation techniques.

  5. Standard Model of Particle Physics--a health physics perspective.

    PubMed

    Bevelacqua, J J

    2010-11-01

    The Standard Model of Particle Physics is reviewed with an emphasis on its relationship to the physics supporting the health physics profession. Concepts important to health physics are emphasized and specific applications are presented. The capability of the Standard Model to provide health physics relevant information is illustrated with application of conservation laws to neutron and muon decay and in the calculation of the neutron mean lifetime.

  6. Building mental models by dissecting physical models.

    PubMed

    Srivastava, Anveshna

    2016-01-01

    When students build physical models from prefabricated components to learn about model systems, there is an implicit trade-off between the physical degrees of freedom in building the model and the intensity of instructor supervision needed. Models that are too flexible, permitting multiple possible constructions require greater supervision to ensure focused learning; models that are too constrained require less supervision, but can be constructed mechanically, with little to no conceptual engagement. We propose "model-dissection" as an alternative to "model-building," whereby instructors could make efficient use of supervisory resources, while simultaneously promoting focused learning. We report empirical results from a study conducted with biology undergraduate students, where we demonstrate that asking them to "dissect" out specific conceptual structures from an already built 3D physical model leads to a significant improvement in performance than asking them to build the 3D model from simpler components. Using questionnaires to measure understanding both before and after model-based interventions for two cohorts of students, we find that both the "builders" and the "dissectors" improve in the post-test, but it is the latter group who show statistically significant improvement. These results, in addition to the intrinsic time-efficiency of "model dissection," suggest that it could be a valuable pedagogical tool. © 2015 The International Union of Biochemistry and Molecular Biology.

  7. Detector Modeling in Astroparticle Physics

    NASA Astrophysics Data System (ADS)

    Petrera, Sergio

    2007-12-01

    Detector modeling is an important step for the interpretation of experimental data in astroparticle physics. In this paper the most specific features of such process are shown, making use of two remarkable examples: the atmospheric neutrinos in MACRO and the Ultra High Energy cosmic rays in the Pierre Auger experiment.

  8. Accelerator physics and modeling: Proceedings

    SciTech Connect

    Parsa, Z.

    1991-01-01

    This report contains papers on the following topics: Physics of high brightness beams; radio frequency beam conditioner for fast-wave free-electron generators of coherent radiation; wake-field and space-charge effects on high brightness beams. Calculations and measured results for BNL-ATF; non-linear orbit theory and accelerator design; general problems of modeling for accelerators; development and application of dispersive soft ferrite models for time-domain simulation; and bunch lengthening in the SLC damping rings.

  9. Accelerator physics and modeling: Proceedings

    SciTech Connect

    Parsa, Z.

    1991-12-31

    This report contains papers on the following topics: Physics of high brightness beams; radio frequency beam conditioner for fast-wave free-electron generators of coherent radiation; wake-field and space-charge effects on high brightness beams. Calculations and measured results for BNL-ATF; non-linear orbit theory and accelerator design; general problems of modeling for accelerators; development and application of dispersive soft ferrite models for time-domain simulation; and bunch lengthening in the SLC damping rings.

  10. A physical model for dementia

    NASA Astrophysics Data System (ADS)

    Sotolongo-Costa, O.; Gaggero-Sager, L. M.; Becker, J. T.; Maestu, F.; Sotolongo-Grau, O.

    2017-04-01

    Aging associated brain decline often result in some kind of dementia. Even when this is a complex brain disorder a physical model can be used in order to describe its general behavior. A probabilistic model for the development of dementia is obtained and fitted to some experimental data obtained from the Alzheimer's Disease Neuroimaging Initiative. It is explained how dementia appears as a consequence of aging and why it is irreversible.

  11. A physical model for dementia.

    PubMed

    Sotolongo-Costa, O; Gaggero-Sager, L M; Becker, J T; Maestu, F; Sotolongo-Grau, O

    2017-04-15

    Aging associated brain decline often result in some kind of dementia. Even when this is a complex brain disorder a physical model can be used in order to describe its general behavior. A probabilistic model for the development of dementia is obtained and fitted to some experimental data obtained from the Alzheimer's Disease Neuroimaging Initiative. It is explained how dementia appears as a consequence of aging and why it is irreversible.

  12. Physical and mathematical cochlear models

    NASA Astrophysics Data System (ADS)

    Lim, Kian-Meng

    2000-10-01

    The cochlea is an intricate organ in the inner ear responsible for our hearing. Besides acting as a transducer to convert mechanical sound vibrations to electrical neural signals, the cochlea also amplifies and separates the sound signal into its spectral components for further processing in the brain. It operates over a broad-band of frequency and a huge dynamic range of input while maintaining a low power consumption. The present research takes the approach of building cochlear models to study and understand the underlying mechanics involved in the functioning of the cochlea. Both physical and mathematical models of the cochlea are constructed. The physical model is a first attempt to build a life- sized replica of the human cochlea using advanced micro- machining techniques. The model takes a modular design, with a removable silicon-wafer based partition membrane encapsulated in a plastic fluid chamber. Preliminary measurements in the model are obtained and they compare roughly with simulation results. Parametric studies on the design parameters of the model leads to an improved design of the model. The studies also revealed that the width and orthotropy of the basilar membrane in the cochlea have significant effects on the sharply tuned responses observed in the biological cochlea. The mathematical model is a physiologically based model that includes three-dimensional viscous fluid flow and a tapered partition with variable properties along its length. A hybrid asymptotic and numerical method provides a uniformly valid and efficient solution to the short and long wave regions in the model. Both linear and non- linear activity are included in the model to simulate the active cochlea. The mathematical model has successfully reproduced many features of the response in the biological cochlea, as observed in experiment measurements performed on animals. These features include sharply tuned frequency responses, significant amplification with inclusion of activity

  13. Modeling Cyber Physical War Gaming

    DTIC Science & Technology

    2017-08-07

    model-based analysis with experiences of an actual tabletop war game, and offer recommendations on using game-theoretic analysis for enhancing accuracy...execution of the scenario; let the Red cell attack, Blue cell defend, and White cell declare the status as it evolves; and inject additional events to...Description Cost ($) No action (j=0) Basic security (j=1) IDS+ (j=2) IDS enhanced (j=3) IDS+ and physical security (j=4) 1 Upgrade WiFi

  14. Sensitivity study of proton radiography and comparison with kV and MV x-ray imaging using GEANT4 Monte Carlo simulations

    NASA Astrophysics Data System (ADS)

    Depauw, Nicolas; Seco, Joao

    2011-04-01

    The imaging sensitivity of proton radiography has been studied and compared with kV and MV x-ray imaging using Monte Carlo simulations. A phantom was specifically modeled using 21 different material inserts with densities ranging from 0.001 to 1.92 g cm-3. These simulations were run using the MGH double scattered proton beam, scanned pencil proton beams from 200 to 490 MeV, as well as pure 50 keV, 100 keV, 1 MeV and 2 MeV gamma x-ray beams. In order to compare the physics implied in both proton and photon radiography without being biased by the current state of the art in detector technology, the detectors were considered perfect. Along with spatial resolution, the contrast-to-noise ratio was evaluated and compared for each material. These analyses were performed using radiographic images that took into account the following: only primary protons, both primary and secondary protons, and both contributions while performing angular and energetic cuts. Additionally, tissue-to-tissue contrasts in an actual lung cancer patient case were studied for simulated proton radiographs and compared against the original kV x-ray image which corresponds to the current patient set-up image in the proton clinic. This study highlights the poorer spatial resolution of protons versus x-rays for radiographic imaging purposes, and the excellent density resolution of proton radiography. Contrasts around the tumor are higher using protons in a lung cancer patient case. The high-density resolution of proton radiography is of great importance for specific tumor diagnostics, such as in lung cancer, where x-ray radiography operates poorly. Furthermore, the use of daily proton radiography prior to proton therapy would ameliorate patient set-up while reducing the absorbed dose delivered through imaging.

  15. Sensitivity study of proton radiography and comparison with kV and MV x-ray imaging using GEANT4 Monte Carlo simulations.

    PubMed

    Depauw, Nicolas; Seco, Joao

    2011-04-21

    The imaging sensitivity of proton radiography has been studied and compared with kV and MV x-ray imaging using Monte Carlo simulations. A phantom was specifically modeled using 21 different material inserts with densities ranging from 0.001 to 1.92 g cm(-3). These simulations were run using the MGH double scattered proton beam, scanned pencil proton beams from 200 to 490 MeV, as well as pure 50 keV, 100 keV, 1 MeV and 2 MeV gamma x-ray beams. In order to compare the physics implied in both proton and photon radiography without being biased by the current state of the art in detector technology, the detectors were considered perfect. Along with spatial resolution, the contrast-to-noise ratio was evaluated and compared for each material. These analyses were performed using radiographic images that took into account the following: only primary protons, both primary and secondary protons, and both contributions while performing angular and energetic cuts. Additionally, tissue-to-tissue contrasts in an actual lung cancer patient case were studied for simulated proton radiographs and compared against the original kV x-ray image which corresponds to the current patient set-up image in the proton clinic. This study highlights the poorer spatial resolution of protons versus x-rays for radiographic imaging purposes, and the excellent density resolution of proton radiography. Contrasts around the tumor are higher using protons in a lung cancer patient case. The high-density resolution of proton radiography is of great importance for specific tumor diagnostics, such as in lung cancer, where x-ray radiography operates poorly. Furthermore, the use of daily proton radiography prior to proton therapy would ameliorate patient set-up while reducing the absorbed dose delivered through imaging.

  16. Patient specific physical anatomy models.

    PubMed

    Cameron, B M; Holmes, D R; Rettmann, M E; Robb, R A

    2008-01-01

    The advent of small footprint stereo-lithographic printers and the ready availability of segmentation and surface modeling software provide a unique opportunity to create patient-specific physical models of anatomy, validation of image guided intervention applications against phantoms that exhibit naturally occurring anatomic variation. Because these models can incorporate all structures relevant to a procedure, this allows validation to occur under realistic conditions using the same or similar techniques as would be used in a clinical application. This in turn reduces the number of trials and time spent performing in-vivo validation experiments. In this paper, we describe our general approach for the creation of both non-tissue and tissue-mimicking patient-specific models as part of a general-purpose patient emulation system used to validate image guided intervention applications.

  17. Modelization For Electromagnetic Electron Scattering at Low Energies for Radiotherapy applications.

    NASA Astrophysics Data System (ADS)

    Nazaryan, Vahagn; Gueye, Paul

    2006-03-01

    Since release of the GEANT4 particle simulation toolkit in 2003, there has been a growing interest in its applications to medical physics. The applicability of GEANT4 to radiotherapy has been a subject of several investigations in recent years, and it was found to be of great use. Its low-energy model allows for electromagnetic interaction simulations down to 250 eV. The electron physics data are obtained from the Lawrence Livermore National Laboratory's Evaluated Electron Data Library (EEDL). At very lower energies (below 10 MeV), some of the tabulated data in EEDL have big uncertainties (more than 50%), and rely on various extrapolations to energy regions where there is no experimental data. We have investigated the variations of these cross-section data to radiotherapy applications. Our study suggests a strong need for better theoretical models of electron interactions with matter at these energies, and the necessity of new and more reliable experimental data. The progress towards such theoretical model will be presented.

  18. Exclusive data-based modeling of neutron-nuclear reactions below 20 MeV

    NASA Astrophysics Data System (ADS)

    Savin, Dmitry; Kosov, Mikhail

    2017-09-01

    We are developing CHIPS-TPT physics library for exclusive simulation of neutron-nuclear reactions below 20 MeV. Exclusive modeling reproduces each separate scattering and thus requires conservation of energy, momentum and quantum numbers in each reaction. Inclusive modeling reproduces only selected values while averaging over the others and imposes no such constraints. Therefore the exclusive modeling allows to simulate additional quantities like secondary particle correlations and gamma-lines broadening and avoid artificial fluctuations. CHIPS-TPT is based on the formerly included in Geant4 CHIPS library, which follows the exclusive approach, and extends it to incident neutrons with the energy below 20 MeV. The NeutronHP model for neutrons below 20 MeV included in Geant4 follows the inclusive approach like the well known MCNP code. Unfortunately, the available data in this energy region is mostly presented in ENDF-6 format and semi-inclusive. Imposing additional constraints on secondary particles complicates modeling but also allows to detect inconsistencies in the input data and to avoid errors that may remain unnoticed in inclusive modeling.

  19. Excellence in Physics Education Award: Modeling Theory for Physics Instruction

    NASA Astrophysics Data System (ADS)

    Hestenes, David

    2014-03-01

    All humans create mental models to plan and guide their interactions with the physical world. Science has greatly refined and extended this ability by creating and validating formal scientific models of physical things and processes. Research in physics education has found that mental models created from everyday experience are largely incompatible with scientific models. This suggests that the fundamental problem in learning and understanding science is coordinating mental models with scientific models. Modeling Theory has drawn on resources of cognitive science to work out extensive implications of this suggestion and guide development of an approach to science pedagogy and curriculum design called Modeling Instruction. Modeling Instruction has been widely applied to high school physics and, more recently, to chemistry and biology, with noteworthy results.

  20. Cabin Environment Physics Risk Model

    NASA Technical Reports Server (NTRS)

    Mattenberger, Christopher J.; Mathias, Donovan Leigh

    2014-01-01

    This paper presents a Cabin Environment Physics Risk (CEPR) model that predicts the time for an initial failure of Environmental Control and Life Support System (ECLSS) functionality to propagate into a hazardous environment and trigger a loss-of-crew (LOC) event. This physics-of failure model allows a probabilistic risk assessment of a crewed spacecraft to account for the cabin environment, which can serve as a buffer to protect the crew during an abort from orbit and ultimately enable a safe return. The results of the CEPR model replace the assumption that failure of the crew critical ECLSS functionality causes LOC instantly, and provide a more accurate representation of the spacecraft's risk posture. The instant-LOC assumption is shown to be excessively conservative and, moreover, can impact the relative risk drivers identified for the spacecraft. This, in turn, could lead the design team to allocate mass for equipment to reduce overly conservative risk estimates in a suboptimal configuration, which inherently increases the overall risk to the crew. For example, available mass could be poorly used to add redundant ECLSS components that have a negligible benefit but appear to make the vehicle safer due to poor assumptions about the propagation time of ECLSS failures.

  1. A Multivariate Model of Physics Problem Solving

    ERIC Educational Resources Information Center

    Taasoobshirazi, Gita; Farley, John

    2013-01-01

    A model of expertise in physics problem solving was tested on undergraduate science, physics, and engineering majors enrolled in an introductory-level physics course. Structural equation modeling was used to test hypothesized relationships among variables linked to expertise in physics problem solving including motivation, metacognitive planning,…

  2. A Multivariate Model of Physics Problem Solving

    ERIC Educational Resources Information Center

    Taasoobshirazi, Gita; Farley, John

    2013-01-01

    A model of expertise in physics problem solving was tested on undergraduate science, physics, and engineering majors enrolled in an introductory-level physics course. Structural equation modeling was used to test hypothesized relationships among variables linked to expertise in physics problem solving including motivation, metacognitive planning,…

  3. Constructing a Model of Physics Expertise

    NASA Astrophysics Data System (ADS)

    Rodriguez, Idaykis; Brewe, Eric; Kramer, Laird

    2010-10-01

    Research on physics expertise has predominantly focused on cognitive differences between physics experts and novices where the novices are high school or introductory college students and the experts are university physics professors or graduate doctoral students. Most physics expertise studies declare the experts to be the physics faculty without justifying this decision. To establish more clearly the characteristics of physics experts, we conducted a qualitative interview pilot study of three university physics professors. The professors each had an hour-long interview where they were asked about their experiences of becoming a physics expert. We present the analysis of the question, `What makes a physics expert?' Analysis of the data resulted in the construction of a model of physics expertise, which indicates that a physics expert is a specific physics expert first, acquires general physics expert characteristics and then becomes an expert in physics or a boundary crosser.

  4. Modeling QCD for Hadron Physics

    SciTech Connect

    Tandy, P. C.

    2011-10-24

    We review the approach to modeling soft hadron physics observables based on the Dyson-Schwinger equations of QCD. The focus is on light quark mesons and in particular the pseudoscalar and vector ground states, their decays and electromagnetic couplings. We detail the wide variety of observables that can be correlated by a ladder-rainbow kernel with one infrared parameter fixed to the chiral quark condensate. A recently proposed novel perspective in which the quark condensate is contained within hadrons and not the vacuum is mentioned. The valence quark parton distributions, in the pion and kaon, as measured in the Drell Yan process, are investigated with the same ladder-rainbow truncation of the Dyson-Schwinger and Bethe-Salpeter equations.

  5. Geant4 simulation of the PSI LEM beam line: energy loss and muonium formation in thin foils and the impact of unmoderated muons on the μSR spectrometer

    NASA Astrophysics Data System (ADS)

    Khaw, K. S.; Antognini, A.; Crivelli, P.; Kirch, K.; Morenzoni, E.; Salman, Z.; Suter, A.; Prokscha, T.

    2015-10-01

    The PSI low-energy μSR spectrometer is an instrument dedicated to muon spin rotation and relaxation measurements. Knowledge of the muon beam parameters such as spatial, kinetic energy and arrival-time distributions at the sample position are important ingredients to analyze the μSR spectra. We present here the measured energy losses in the thin carbon foil of the muon start detector deduced from time-of-flight measurements. Muonium formation in the thin carbon foil (10 nm thickness) of the muon start detector also affect the measurable decay asymmetry and therefore need to be accounted for. Muonium formation and energy losses in the start detector, whose relevance increase with decreasing muon implantation energy (<10 keV), have been implemented in Geant4 Monte Carlo simulation to reproduce the measured time-of-flight spectra. Simulated and measured time-of-flight and beam spot agrees only if a small fraction of so called ``unmoderated'' muons which contaminate the mono-energetic muon beam of the μSR spectrometer is introduced. Moreover the sensitivity of the beam size and related upstream-downstream asymmetry for a specially shaped ``nose'' sample plate has been studied for various beam line settings, which is of relevance for the study of thermal muonium emission into vacuum from mesoporous silica at cryogenic temperatures.

  6. Determination and Fabrication of New Shield Super Alloys Materials for Nuclear Reactor Safety by Experiments and Cern-Fluka Monte Carlo Simulation Code, Geant4 and WinXCom

    NASA Astrophysics Data System (ADS)

    Aygun, Bünyamin; Korkut, Turgay; Karabulut, Abdulhalik

    2016-05-01

    Despite the possibility of depletion of fossil fuels increasing energy needs the use of radiation tends to increase. Recently the security-focused debate about planned nuclear power plants still continues. The objective of this thesis is to prevent the radiation spread from nuclear reactors into the environment. In order to do this, we produced higher performanced of new shielding materials which are high radiation holders in reactors operation. Some additives used in new shielding materials; some of iron (Fe), rhenium (Re), nickel (Ni), chromium (Cr), boron (B), copper (Cu), tungsten (W), tantalum (Ta), boron carbide (B4C). The results of this experiments indicated that these materials are good shields against gamma and neutrons. The powder metallurgy technique was used to produce new shielding materials. CERN - FLUKA Geant4 Monte Carlo simulation code and WinXCom were used for determination of the percentages of high temperature resistant and high-level fast neutron and gamma shielding materials participated components. Super alloys was produced and then the experimental fast neutron dose equivalent measurements and gamma radiation absorpsion of the new shielding materials were carried out. The produced products to be used safely reactors not only in nuclear medicine, in the treatment room, for the storage of nuclear waste, nuclear research laboratories, against cosmic radiation in space vehicles and has the qualities.

  7. Physics modeling support contract: Final report

    SciTech Connect

    Not Available

    1987-09-30

    This document is the final report for the Physics Modeling Support contract between TRW, Inc. and the Lawrence Livermore National Laboratory for fiscal year 1987. It consists of following projects: TIBER physics modeling and systems code development; advanced blanket modeling task; time dependent modeling; and free electron maser for TIBER II.

  8. Model Formulation for Physics Problem Solving. Draft.

    ERIC Educational Resources Information Center

    Novak, Gordon S., Jr.

    The major task in solving a physics problem is to construct an appropriate model of the problem in terms of physical principles. The functions performed by such a model, the information which needs to be represented, and the knowledge used in selecting and instantiating an appropriate model are discussed. An example of a model for a mechanics…

  9. Physical modeling of Tibetan bowls

    NASA Astrophysics Data System (ADS)

    Antunes, Jose; Inacio, Octavio

    2001-05-01

    Tibetan bowls produce rich penetrating sounds, used in musical contexts and to induce a state of relaxation for meditation or therapy purposes. To understand the dynamics of these instruments under impact and rubbing excitation, we developed a simulation method based on the modal approach, following our previous papers on physical modeling of plucked/bowed strings and impacted/bowed bars. This technique is based on a compact representation of the system dynamics, in terms of the unconstrained bowl modes. Nonlinear contact/friction interaction forces, between the exciter (puja) and the bowl, are computed at each time step and projected on the bowl modal basis, followed by step integration of the modal equations. We explore the behavior of two different-sized bowls, for extensive ranges of excitation conditions (contact/friction parameters, normal force, and tangential puja velocity). Numerical results and experiments show that various self-excited motions may arise depending on the playing conditions and, mainly, on the contact/friction interaction parameters. Indeed, triggering of a given bowl modal frequency mainly depends on the puja material. Computed animations and experiments demonstrate that self-excited modes spin, following the puja motion. Accordingly, the sensed pressure field pulsates, with frequency controlled by the puja spinning velocity and the spatial pattern of the singing mode.

  10. Physical modeling of Tibetan bowls

    NASA Astrophysics Data System (ADS)

    Antunes, Jose; Inacio, Octavio

    2004-05-01

    Tibetan bowls produce rich penetrating sounds, used in musical contexts and to induce a state of relaxation for meditation or therapy purposes. To understand the dynamics of these instruments under impact and rubbing excitation, we developed a simulation method based on the modal approach, following our previous papers on physical modeling of plucked/bowed strings and impacted/bowed bars. This technique is based on a compact representation of the system dynamics, in terms of the unconstrained bowl modes. Nonlinear contact/friction interaction forces, between the exciter (puja) and the bowl, are computed at each time step and projected on the bowl modal basis, followed by step integration of the modal equations. We explore the behavior of two different-sized bowls, for extensive ranges of excitation conditions (contact/friction parameters, normal force, and tangential puja velocity). Numerical results and experiments show that various self-excited motions may arise depending on the playing conditions and, mainly, on the contact/friction interaction parameters. Indeed, triggering of a given bowl modal frequency mainly depends on the puja material. Computed animations and experiments demonstrate that self-excited modes spin, following the puja motion. Accordingly, the sensed pressure field pulsates, with frequency controlled by the puja spinning velocity and the spatial pattern of the singing mode.

  11. NUMERICAL MODELING OF FINE SEDIMENT PHYSICAL PROCESSES.

    USGS Publications Warehouse

    Schoellhamer, David H.

    1985-01-01

    Fine sediment in channels, rivers, estuaries, and coastal waters undergo several physical processes including flocculation, floc disruption, deposition, bed consolidation, and resuspension. This paper presents a conceptual model and reviews mathematical models of these physical processes. Several general fine sediment models that simulate some of these processes are reviewed. These general models do not directly simulate flocculation and floc disruption, but the conceptual model and existing functions are shown to adequately model these two processes for one set of laboratory data.

  12. Beta-gamma coincidence counting efficiency and energy resolution optimization by Geant4 Monte Carlo simulations for a phoswich well detector.

    PubMed

    Zhang, Weihua; Mekarski, Pawel; Ungar, Kurt

    2010-12-01

    A single-channel phoswich well detector has been assessed and analysed in order to improve beta-gamma coincidence measurement sensitivity of (131m)Xe and (133m)Xe. This newly designed phoswich well detector consists of a plastic cell (BC-404) embedded in a CsI(Tl) crystal coupled to a photomultiplier tube (PMT). It can be used to distinguish 30.0-keV X-ray signals of (131m)Xe and (133m)Xe using their unique coincidence signatures between the conversion electrons (CEs) and the 30.0-keV X-rays. The optimum coincidence efficiency signal depends on the energy resolutions of the two CE peaks, which could be affected by relative positions of the plastic cell to the CsI(Tl) because the embedded plastic cell would interrupt scintillation light path from the CsI(Tl) crystal to the PMT. In this study, several relative positions between the embedded plastic cell and the CsI(Tl) crystal have been evaluated using Monte Carlo modeling for its effects on coincidence detection efficiency and X-ray and CE energy resolutions. The results indicate that the energy resolution and beta-gamma coincidence counting efficiency of X-ray and CE depend significantly on the plastic cell locations inside the CsI(Tl). The degraded X-ray and CE peak energy resolutions due to light collection efficiency deterioration by the embedded cell can be minimised. The optimum of CE and X-ray energy resolution, beta-gamma coincidence efficiency as well as the ease of manufacturing could be achieved by varying the embedded plastic cell positions inside the CsI(Tl) and consequently setting the most efficient geometry. Crown Copyright © 2010. Published by Elsevier Ltd. All rights reserved.

  13. Evaluating a Model of Youth Physical Activity

    ERIC Educational Resources Information Center

    Heitzler, Carrie D.; Lytle, Leslie A.; Erickson, Darin J.; Barr-Anderson, Daheia; Sirard, John R.; Story, Mary

    2010-01-01

    Objective: To explore the relationship between social influences, self-efficacy, enjoyment, and barriers and physical activity. Methods: Structural equation modeling examined relationships between parent and peer support, parent physical activity, individual perceptions, and objectively measured physical activity using accelerometers among a…

  14. SU-E-T-289: Scintillating Fiber Based In-Vivo Dose Monitoring System to the Rectum in Proton Therapy of Prostate Cancer: A Geant4 Monte Carlo Simulation

    SciTech Connect

    Tesfamicael, B; Gueye, P; Lyons, D; Mahesh, M; Avery, S

    2014-06-01

    Purpose: To construct a dose monitoring system based on an endorectal balloon coupled to thin scintillating fibers to study the dose delivered to the rectum during prostate cancer proton therapy Methods: The Geant4 Monte Carlo toolkit version 9.6p02 was used to simulate prostate cancer proton therapy treatments of an endorectal balloon (for immobilization of a 2.9 cm diameter prostate gland) and a set of 34 scintillating fibers symmetrically placed around the balloon and perpendicular to the proton beam direction (for dosimetry measurements) Results: A linear response of the fibers to the dose delivered was observed within <2%, a property that makes them good candidates for real time dosimetry. Results obtained show that the closest fiber recorded about 1/3 of the dose to the target with a 1/r{sup 2} decrease in the dose distribution as one goes toward the frontal and distal top fibers. Very low dose was recorded by the bottom fibers (about 45 times comparatively), which is a clear indication that the overall volume of the rectal wall that is exposed to a higher dose is relatively minimized. Further analysis indicated a simple scaling relationship between the dose to the prostate and the dose to the top fibers (a linear fit gave a slope of −0.07±0.07 MeV per treatment Gy) Conclusion: Thin (1 mm × 1 mm × 100 cm) long scintillating fibers were found to be ideal for real time in-vivo dose measurement to the rectum for prostate cancer proton therapy. The linear response of the fibers to the dose delivered makes them good candidates of dosimeters. With thorough calibration and the ability to define a good correlation between the dose to the target and the dose to the fibers, such dosimeters can be used for real time dose verification to the target.

  15. Comprehensive Physical Education Program Model

    ERIC Educational Resources Information Center

    Kamiya, Artie

    2005-01-01

    In 2004, the Wake County Public School System (North Carolina) received $1.3 million as one of 237 national winners of the $70 million federal Carol M. White Physical Education Program (PEP) Grant competition. The PEP Grant program is funded by the U.S. Department of Education and provides monies to school districts able to demonstrate the…

  16. Comprehensive Physical Education Program Model

    ERIC Educational Resources Information Center

    Kamiya, Artie

    2005-01-01

    In 2004, the Wake County Public School System (North Carolina) received $1.3 million as one of 237 national winners of the $70 million federal Carol M. White Physical Education Program (PEP) Grant competition. The PEP Grant program is funded by the U.S. Department of Education and provides monies to school districts able to demonstrate the…

  17. PIXE simulation: Models, methods and technologies

    SciTech Connect

    Batic, M.; Pia, M. G.; Saracco, P.; Weidenspointner, G.

    2013-04-19

    The simulation of PIXE (Particle Induced X-ray Emission) is discussed in the context of general-purpose Monte Carlo systems for particle transport. Dedicated PIXE codes are mainly concerned with the application of the technique to elemental analysis, but they lack the capability of dealing with complex experimental configurations. General-purpose Monte Carlo codes provide powerful tools to model the experimental environment in great detail, but so far they have provided limited functionality for PIXE simulation. This paper reviews recent developments that have endowed the Geant4 simulation toolkit with advanced capabilities for PIXE simulation, and related efforts for quantitative validation of cross sections and other physical parameters relevant to PIXE simulation.

  18. Are Physical Education Majors Models for Fitness?

    ERIC Educational Resources Information Center

    Kamla, James; Snyder, Ben; Tanner, Lori; Wash, Pamela

    2012-01-01

    The National Association of Sport and Physical Education (NASPE) (2002) has taken a firm stance on the importance of adequate fitness levels of physical education teachers stating that they have the responsibility to model an active lifestyle and to promote fitness behaviors. Since the NASPE declaration, national initiatives like Let's Move…

  19. Bridging physics and biology teaching through modeling

    NASA Astrophysics Data System (ADS)

    Hoskinson, Anne-Marie; Couch, Brian A.; Zwickl, Benjamin M.; Hinko, Kathleen A.; Caballero, Marcos D.

    2014-05-01

    As the frontiers of biology become increasingly interdisciplinary, the physics education community has engaged in ongoing efforts to make physics classes more relevant to life science majors. These efforts are complicated by the many apparent differences between these fields, including the types of systems that each studies, the behavior of those systems, the kinds of measurements that each makes, and the role of mathematics in each field. Nonetheless, physics and biology are both sciences that rely on observations and measurements to construct models of the natural world. In this article, we propose that efforts to bridge the teaching of these two disciplines must emphasize shared scientific practices, particularly scientific modeling. We define modeling using language common to both disciplines and highlight how an understanding of the modeling process can help reconcile apparent differences between the teaching of physics and biology. We elaborate on how models can be used for explanatory, predictive, and functional purposes and present common models from each discipline demonstrating key modeling principles. By framing interdisciplinary teaching in the context of modeling, we aim to bridge physics and biology teaching and to equip students with modeling competencies applicable in any scientific discipline.

  20. Modeling Physics with Easy Java Simulations

    ERIC Educational Resources Information Center

    Christian, Wolfgang; Esquembre, Francisco

    2007-01-01

    Modeling has been shown to correct weaknesses of traditional instruction by engaging students in the design of physical models to describe, explain, and predict phenomena. Although the modeling method can be used without computers, the use of computers allows students to study problems that are difficult and time consuming, to visualize their…

  1. Modeling Physics with Easy Java Simulations

    ERIC Educational Resources Information Center

    Christian, Wolfgang; Esquembre, Francisco

    2007-01-01

    Modeling has been shown to correct weaknesses of traditional instruction by engaging students in the design of physical models to describe, explain, and predict phenomena. Although the modeling method can be used without computers, the use of computers allows students to study problems that are difficult and time consuming, to visualize their…

  2. The trinucleons: Physical observables and model properties

    SciTech Connect

    Gibson, B.F.

    1992-01-01

    Our progress in understanding the properties of {sup 3}H and {sup 3}He in terms of a nonrelativistic Hamiltonian picture employing realistic nuclear forces is reviewed. Trinucleon model properties are summarized for a number of contemporary force models, and predictions for physical observables are presented. Disagreement between theoretical model results and experimental results are highlighted.

  3. The trinucleons: Physical observables and model properties

    SciTech Connect

    Gibson, B.F.

    1992-05-01

    Our progress in understanding the properties of {sup 3}H and {sup 3}He in terms of a nonrelativistic Hamiltonian picture employing realistic nuclear forces is reviewed. Trinucleon model properties are summarized for a number of contemporary force models, and predictions for physical observables are presented. Disagreement between theoretical model results and experimental results are highlighted.

  4. The Standard Model of Nuclear Physics

    NASA Astrophysics Data System (ADS)

    Detmold, William

    2015-04-01

    At its core, nuclear physics, which describes the properties and interactions of hadrons, such as protons and neutrons, and atomic nuclei, arises from the Standard Model of particle physics. However, the complexities of nuclei result in severe computational difficulties that have historically prevented the calculation of central quantities in nuclear physics directly from this underlying theory. The availability of petascale (and prospect of exascale) high performance computing is changing this situation by enabling us to extend the numerical techniques of lattice Quantum Chromodynamics (LQCD), applied successfully in particle physics, to the more intricate dynamics of nuclear physics. In this talk, I will discuss this revolution and the emerging understanding of hadrons and nuclei within the Standard Model.

  5. Developing + Using Models in Physics

    ERIC Educational Resources Information Center

    Campbell, Todd; Neilson, Drew; Oh, Phil Seok

    2013-01-01

    Of the eight practices of science identified in "A Framework for K-12 Science Education" (NRC 2012), helping students develop and use models has been identified by many as an anchor (Schwarz and Passmore 2012; Windschitl 2012). In instruction, disciplinary core ideas, crosscutting concepts, and scientific practices can be meaningfully…

  6. Developing + Using Models in Physics

    ERIC Educational Resources Information Center

    Campbell, Todd; Neilson, Drew; Oh, Phil Seok

    2013-01-01

    Of the eight practices of science identified in "A Framework for K-12 Science Education" (NRC 2012), helping students develop and use models has been identified by many as an anchor (Schwarz and Passmore 2012; Windschitl 2012). In instruction, disciplinary core ideas, crosscutting concepts, and scientific practices can be meaningfully…

  7. Physics of the Quark Model

    ERIC Educational Resources Information Center

    Young, Robert D.

    1973-01-01

    Discusses the charge independence, wavefunctions, magnetic moments, and high-energy scattering of hadrons on the basis of group theory and nonrelativistic quark model with mass spectrum calculated by first-order perturbation theory. The presentation is explainable to advanced undergraduate students. (CC)

  8. Physics of the Quark Model

    ERIC Educational Resources Information Center

    Young, Robert D.

    1973-01-01

    Discusses the charge independence, wavefunctions, magnetic moments, and high-energy scattering of hadrons on the basis of group theory and nonrelativistic quark model with mass spectrum calculated by first-order perturbation theory. The presentation is explainable to advanced undergraduate students. (CC)

  9. Modeling low energy x-ray interactions with biological material at the CUEBIT

    NASA Astrophysics Data System (ADS)

    Klingenberger, J.; Schott, M.; Kimmel, T.; Medlin, D.; Gall, A.; Rusin, M.; Dean, D.; Takacs, E.

    2015-01-01

    Recent developments at Clemson University have established the need to model the production of x-rays using a highly charged ion beam generated by the Clemson University Electron Beam Ion Trap (CUEBIT). A Geant4 modeling environment has been developed on Clemson University's Palmetto2 supercomputing cluster to simulate the interaction of these x- rays with biological material. Preliminary results of the model have been obtained after performing initial simulations on the computing cluster. Future experiments using the CUEBIT as well as refinements to the Geant4 model are discussed.

  10. PHYSICAL MODELING OF CONTRACTED FLOW.

    USGS Publications Warehouse

    Lee, Jonathan K.

    1987-01-01

    Experiments on steady flow over uniform grass roughness through centered single-opening contractions were conducted in the Flood Plain Simulation Facility at the U. S. Geological Survey's Gulf Coast Hydroscience Center near Bay St. Louis, Miss. The experimental series was designed to provide data for calibrating and verifying two-dimensional, vertically averaged surface-water flow models used to simulate flow through openings in highway embankments across inundated flood plains. Water-surface elevations, point velocities, and vertical velocity profiles were obtained at selected locations for design discharges ranging from 50 to 210 cfs. Examples of observed water-surface elevations and velocity magnitudes at basin cross-sections are presented.

  11. Modelling Mathematical Reasoning in Physics Education

    NASA Astrophysics Data System (ADS)

    Uhden, Olaf; Karam, Ricardo; Pietrocola, Maurício; Pospiech, Gesche

    2012-04-01

    Many findings from research as well as reports from teachers describe students' problem solving strategies as manipulation of formulas by rote. The resulting dissatisfaction with quantitative physical textbook problems seems to influence the attitude towards the role of mathematics in physics education in general. Mathematics is often seen as a tool for calculation which hinders a conceptual understanding of physical principles. However, the role of mathematics cannot be reduced to this technical aspect. Hence, instead of putting mathematics away we delve into the nature of physical science to reveal the strong conceptual relationship between mathematics and physics. Moreover, we suggest that, for both prospective teaching and further research, a focus on deeply exploring such interdependency can significantly improve the understanding of physics. To provide a suitable basis, we develop a new model which can be used for analysing different levels of mathematical reasoning within physics. It is also a guideline for shifting the attention from technical to structural mathematical skills while teaching physics. We demonstrate its applicability for analysing physical-mathematical reasoning processes with an example.

  12. Particle radiation transport and effects models from research to space weather operations

    NASA Astrophysics Data System (ADS)

    Santin, Giovanni; Nieminen, Petteri; Rivera, Angela; Ibarmia, Sergio; Truscott, Pete; Lei, Fan; Desorgher, Laurent; Ivanchenko, Vladimir; Kruglanski, Michel; Messios, Neophytos

    Assessment of risk from potential radiation-induced effects to space systems requires knowledge of both the conditions of the radiation environment and of the impact of radiation on sensi-tive spacecraft elements. During sensitivity analyses, test data are complemented by models to predict how external radiation fields are transported and modified in spacecraft materials. Radiation transport is still itself a subject of research and models are continuously improved to describe the physical interactions that take place when particles pass through shielding materi-als or hit electronic systems or astronauts, sometimes down to nanometre-scale interactions of single particles with deep sub-micron technologies or DNA structures. In recent years, though, such radiation transport models are transitioning from being a research subject by itself, to being widely used in the space engineering domain and finally being directly applied in the context of operation of space weather services. A significant "research to operations" (R2O) case is offered by Geant4, an open source toolkit initially developed and used in the context of fundamental research in high energy physics. Geant4 is also being used in the space domain, e.g. for modelling detector responses in science payloads, but also for studying the radiation environment itself, with subjects ranging from cosmic rays, to solar energetic particles in the heliosphere, to geomagnetic shielding. Geant4-based tools are now becoming more and more integrated in spacecraft design procedures, also through user friendly interfaces such as SPEN-VIS. Some examples are given by MULASSIS, offering multi-layered shielding analysis capa-bilities in realistic spacecraft materials, or GEMAT, focused on micro-dosimetry in electronics, or PLANETOCOSMICS, describing the interaction of the space environment with planetary magneto-and atmospheres, or GRAS, providing a modular and easy to use interface to various analysis types in simple or

  13. Modeling theory applied: Modeling Instruction in introductory physics

    NASA Astrophysics Data System (ADS)

    Brewe, Eric

    2008-12-01

    Modeling Instruction is a pedagogical approach which has been widely and successfully employed in high school physics instruction but is not commonly used at the university level. The goal of this paper is to describe the nature of Modeling Instruction at the university level and to clarify the role of models in physics instruction. A university physics class is described as it progresses through a typical modeling cycle, Introduction and Representation, Coordination of Representations, Abstraction and Generalization, and Application and Refinement. The benefits of modeling instruction are discussed.

  14. Monte Carlo investigation of the increased radiation deposition due to gold nanoparticles using kilovoltage and megavoltage photons in a 3D randomized cell model.

    PubMed

    Douglass, Michael; Bezak, Eva; Penfold, Scott

    2013-07-01

    Investigation of increased radiation dose deposition due to gold nanoparticles (GNPs) using a 3D computational cell model during x-ray radiotherapy. Two GNP simulation scenarios were set up in Geant4; a single 400 nm diameter gold cluster randomly positioned in the cytoplasm and a 300 nm gold layer around the nucleus of the cell. Using an 80 kVp photon beam, the effect of GNP on the dose deposition in five modeled regions of the cell including cytoplasm, membrane, and nucleus was simulated. Two Geant4 physics lists were tested: the default Livermore and custom built Livermore/DNA hybrid physics list. 10(6) particles were simulated at 840 cells in the simulation. Each cell was randomly placed with random orientation and a diameter varying between 9 and 13 μm. A mathematical algorithm was used to ensure that none of the 840 cells overlapped. The energy dependence of the GNP physical dose enhancement effect was calculated by simulating the dose deposition in the cells with two energy spectra of 80 kVp and 6 MV. The contribution from Auger electrons was investigated by comparing the two GNP simulation scenarios while activating and deactivating atomic de-excitation processes in Geant4. The physical dose enhancement ratio (DER) of GNP was calculated using the Monte Carlo model. The model has demonstrated that the DER depends on the amount of gold and the position of the gold cluster within the cell. Individual cell regions experienced statistically significant (p < 0.05) change in absorbed dose (DER between 1 and 10) depending on the type of gold geometry used. The DER resulting from gold clusters attached to the cell nucleus had the more significant effect of the two cases (DER ≈ 55). The DER value calculated at 6 MV was shown to be at least an order of magnitude smaller than the DER values calculated for the 80 kVp spectrum. Based on simulations, when 80 kVp photons are used, Auger electrons have a statistically insignificant (p < 0.05) effect on the overall dose

  15. Monte Carlo investigation of the increased radiation deposition due to gold nanoparticles using kilovoltage and megavoltage photons in a 3D randomized cell model

    SciTech Connect

    Douglass, Michael; Bezak, Eva; Penfold, Scott

    2013-07-15

    Purpose: Investigation of increased radiation dose deposition due to gold nanoparticles (GNPs) using a 3D computational cell model during x-ray radiotherapy.Methods: Two GNP simulation scenarios were set up in Geant4; a single 400 nm diameter gold cluster randomly positioned in the cytoplasm and a 300 nm gold layer around the nucleus of the cell. Using an 80 kVp photon beam, the effect of GNP on the dose deposition in five modeled regions of the cell including cytoplasm, membrane, and nucleus was simulated. Two Geant4 physics lists were tested: the default Livermore and custom built Livermore/DNA hybrid physics list. 10{sup 6} particles were simulated at 840 cells in the simulation. Each cell was randomly placed with random orientation and a diameter varying between 9 and 13 {mu}m. A mathematical algorithm was used to ensure that none of the 840 cells overlapped. The energy dependence of the GNP physical dose enhancement effect was calculated by simulating the dose deposition in the cells with two energy spectra of 80 kVp and 6 MV. The contribution from Auger electrons was investigated by comparing the two GNP simulation scenarios while activating and deactivating atomic de-excitation processes in Geant4.Results: The physical dose enhancement ratio (DER) of GNP was calculated using the Monte Carlo model. The model has demonstrated that the DER depends on the amount of gold and the position of the gold cluster within the cell. Individual cell regions experienced statistically significant (p < 0.05) change in absorbed dose (DER between 1 and 10) depending on the type of gold geometry used. The DER resulting from gold clusters attached to the cell nucleus had the more significant effect of the two cases (DER {approx} 55). The DER value calculated at 6 MV was shown to be at least an order of magnitude smaller than the DER values calculated for the 80 kVp spectrum. Based on simulations, when 80 kVp photons are used, Auger electrons have a statistically insignificant (p

  16. Physical Modelling of Sedimentary Basin

    SciTech Connect

    Yuen, David A.

    2003-04-24

    The main goals of the first three years have been achieved, i.e., the development of particle-based and continuum-based algorithms for cross-scaleup-scale analysis of complex fluid flows. The U. Minnesota team has focused on particle-based methods, wavelets (Rustad et al., 2001) and visualization and has had great success with the dissipative and fluid particle dynamics algorithms, as applied to colloidal, polymeric and biological systems, wavelet filtering and visualization endeavors. We have organized two sessions in nonlinear geophysics at the A.G.U. Fall Meeting (2000,2002), which have indeed synergetically stimulated the community and promoted cross-disciplinary efforts in the geosciences. The LANL team has succeeded with continuum-based algorithms, in particular, fractal interpolating functions (fif). These have been applied to 1-D flow and transport equations (Travis, 2000; 2002) as a proof of principle, providing solutions that capture dynamics at all scales. In addition, the fif representations can be integrated to provide sub-grid-scale homogenization, which can be used in more traditional finite difference or finite element solutions of porous flow and transport. Another useful tool for fluid flow problems is the ability to solve inverse problems, that is, given present-time observations of a fluid flow, what was the initial state of that fluid system? We have demonstrated this capability for a large-scale problem of 3-D flow in the Earth's crust (Bunge, Hagelberg & Travis, 2002). Use of the adjoint method for sensitivity analysis (Marchuk, 1995) to compute derivatives of models makes the large-scale inversion feasible in 4-D, , space and time. Further, a framework for simulating complex fluid flow in the Earth's crust has been implemented (Dutrow et al, 2001). The remaining task of the first three-year campaign is to extend the implementation of the fif formalism to our 2-D and 3-D computer codes, which is straightforward, but involved.

  17. Monte Carlo modeling provides accurate calibration factors for radionuclide activity meters.

    PubMed

    Zagni, F; Cicoria, G; Lucconi, G; Infantino, A; Lodi, F; Marengo, M

    2014-12-01

    Accurate determination of calibration factors for radionuclide activity meters is crucial for quantitative studies and in the optimization step of radiation protection, as these detectors are widespread in radiopharmacy and nuclear medicine facilities. In this work we developed the Monte Carlo model of a widely used activity meter, using the Geant4 simulation toolkit. More precisely the "PENELOPE" EM physics models were employed. The model was validated by means of several certified sources, traceable to primary activity standards, and other sources locally standardized with spectrometry measurements, plus other experimental tests. Great care was taken in order to accurately reproduce the geometrical details of the gas chamber and the activity sources, each of which is different in shape and enclosed in a unique container. Both relative calibration factors and ionization current obtained with simulations were compared against experimental measurements; further tests were carried out, such as the comparison of the relative response of the chamber for a source placed at different positions. The results showed a satisfactory level of accuracy in the energy range of interest, with the discrepancies lower than 4% for all the tested parameters. This shows that an accurate Monte Carlo modeling of this type of detector is feasible using the low-energy physics models embedded in Geant4. The obtained Monte Carlo model establishes a powerful tool for first instance determination of new calibration factors for non-standard radionuclides, for custom containers, when a reference source is not available. Moreover, the model provides an experimental setup for further research and optimization with regards to materials and geometrical details of the measuring setup, such as the ionization chamber itself or the containers configuration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Composing Models of Geographic Physical Processes

    NASA Astrophysics Data System (ADS)

    Hofer, Barbara; Frank, Andrew U.

    Processes are central for geographic information science; yet geographic information systems (GIS) lack capabilities to represent process related information. A prerequisite to including processes in GIS software is a general method to describe geographic processes independently of application disciplines. This paper presents such a method, namely a process description language. The vocabulary of the process description language is derived formally from mathematical models. Physical processes in geography can be described in two equivalent languages: partial differential equations or partial difference equations, where the latter can be shown graphically and used as a method for application specialists to enter their process models. The vocabulary of the process description language comprises components for describing the general behavior of prototypical geographic physical processes. These process components can be composed by basic models of geographic physical processes, which is shown by means of an example.

  19. Simplified Models for LHC New Physics Searches

    SciTech Connect

    Alves, Daniele; Arkani-Hamed, Nima; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua; Buckley, Matthew; Butler, Bart; Chang, Spencer; Cheng, Hsin-Chia; Cheung, Clifford; Chivukula, R.Sekhar; Cho, Won Sang; Cotta, Randy; D'Alfonso, Mariarosaria; El Hedri, Sonia; Essig, Rouven,; Evans, Jared A.; Fitzpatrick, Liam; Fox, Patrick; Franceschini, Roberto; /more authors..

    2012-06-01

    This document proposes a collection of simplified models relevant to the design of new-physics searches at the LHC and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the 'Topologies for Early LHC Searches' workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first {approx} 50-500 pb{sup -1} of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.

  20. Simplified models for LHC new physics searches

    NASA Astrophysics Data System (ADS)

    Alves, Daniele; Arkani-Hamed, Nima; Arora, Sanjay; Bai, Yang; Baumgart, Matthew; Berger, Joshua; Buckley, Matthew; Butler, Bart; Chang, Spencer; Cheng, Hsin-Chia; Cheung, Clifford; Sekhar Chivukula, R.; Cho, Won Sang; Cotta, Randy; D'Alfonso, Mariarosaria; El Hedri, Sonia; Essig (Editor, Rouven; Evans, Jared A.; Fitzpatrick, Liam; Fox, Patrick; Franceschini, Roberto; Freitas, Ayres; Gainer, James S.; Gershtein, Yuri; Gray, Richard; Gregoire, Thomas; Gripaios, Ben; Gunion, Jack; Han, Tao; Haas, Andy; Hansson, Per; Hewett, JoAnne; Hits, Dmitry; Hubisz, Jay; Izaguirre, Eder; Kaplan, Jared; Katz, Emanuel; Kilic, Can; Kim, Hyung-Do; Kitano, Ryuichiro; Koay, Sue Ann; Ko, Pyungwon; Krohn, David; Kuflik, Eric; Lewis, Ian; Lisanti (Editor, Mariangela; Liu, Tao; Liu, Zhen; Lu, Ran; Luty, Markus; Meade, Patrick; Morrissey, David; Mrenna, Stephen; Nojiri, Mihoko; Okui, Takemichi; Padhi, Sanjay; Papucci, Michele; Park, Michael; Park, Myeonghun; Perelstein, Maxim; Peskin, Michael; Phalen, Daniel; Rehermann, Keith; Rentala, Vikram; Roy, Tuhin; Ruderman, Joshua T.; Sanz, Veronica; Schmaltz, Martin; Schnetzer, Stephen; Schuster (Editor, Philip; Schwaller, Pedro; Schwartz, Matthew D.; Schwartzman, Ariel; Shao, Jing; Shelton, Jessie; Shih, David; Shu, Jing; Silverstein, Daniel; Simmons, Elizabeth; Somalwar, Sunil; Spannowsky, Michael; Spethmann, Christian; Strassler, Matthew; Su, Shufang; Tait (Editor, Tim; Thomas, Brooks; Thomas, Scott; Toro (Editor, Natalia; Volansky, Tomer; Wacker (Editor, Jay; Waltenberger, Wolfgang; Yavin, Itay; Yu, Felix; Zhao, Yue; Zurek, Kathryn; LHC New Physics Working Group

    2012-10-01

    This document proposes a collection of simplified models relevant to the design of new-physics searches at the Large Hadron Collider (LHC) and the characterization of their results. Both ATLAS and CMS have already presented some results in terms of simplified models, and we encourage them to continue and expand this effort, which supplements both signature-based results and benchmark model interpretations. A simplified model is defined by an effective Lagrangian describing the interactions of a small number of new particles. Simplified models can equally well be described by a small number of masses and cross-sections. These parameters are directly related to collider physics observables, making simplified models a particularly effective framework for evaluating searches and a useful starting point for characterizing positive signals of new physics. This document serves as an official summary of the results from the ‘Topologies for Early LHC Searches’ workshop, held at SLAC in September of 2010, the purpose of which was to develop a set of representative models that can be used to cover all relevant phase space in experimental searches. Particular emphasis is placed on searches relevant for the first ˜50-500 pb-1 of data and those motivated by supersymmetric models. This note largely summarizes material posted at http://lhcnewphysics.org/, which includes simplified model definitions, Monte Carlo material, and supporting contacts within the theory community. We also comment on future developments that may be useful as more data is gathered and analyzed by the experiments.

  1. Model reduction in the physical coordinate system

    NASA Technical Reports Server (NTRS)

    Yae, K. Harold; Joeng, K. Y.

    1989-01-01

    In the dynamics modeling of a flexible structure, finite element analysis employs reduction techniques, such as Guyan's reduction, to remove some of the insignificant physical coordinates, thus producing a dynamics model that has smaller mass and stiffness matrices. But this reduction is limited in the sense that it removes certain degrees of freedom at a node points themselves in the model. From the standpoint of linear control design, the resultant model is still too large despite the reduction. Thus, some form of the model reduction is frequently used in control design by approximating a large dynamical system with a fewer number of state variables. However, a problem arises from the placement of sensors and actuators in the reduced model, because a model usually undergoes, before being reduced, some form of coordinate transformations that do not preserve the physical meanings of the states. To correct such a problem, a method is developed that expresses a reduced model in terms of a subset of the original states. The proposed method starts with a dynamic model that is originated and reduced in finite element analysis. Then the model is converted to the state space form, and reduced again by the internal balancing method. At this point, being in the balanced coordinate system, the states in the reduced model have no apparent resemblance to those of the original model. Through another coordinate transformation that is developed, however, this reduced model is expressed by a subset of the original states.

  2. Physical and stochastic models of earthquake clustering

    NASA Astrophysics Data System (ADS)

    Console, Rodolfo; Murru, Maura; Catalli, Flaminia

    2006-04-01

    The phenomenon of earthquake clustering, i.e., the increase of occurrence probability for seismic events close in space and time to other previous earthquakes, has been modeled both by statistical and physical processes. From a statistical viewpoint the so-called epidemic model (ETAS) introduced by Ogata in 1988 and its variations have become fairly well known in the seismological community. Tests on real seismicity and comparison with a plain time-independent Poissonian model through likelihood-based methods have reliably proved their validity. On the other hand, in the last decade many papers have been published on the so-called Coulomb stress change principle, based on the theory of elasticity, showing qualitatively that an increase of the Coulomb stress in a given area is usually associated with an increase of seismic activity. More specifically, the rate-and-state theory developed by Dieterich in the '90s has been able to give a physical justification to the phenomenon known as Omori law. According to this law, a mainshock is followed by a series of aftershocks whose frequency decreases in time as an inverse power law. In this study we give an outline of the above-mentioned stochastic and physical models, and build up an approach by which these models can be merged in a single algorithm and statistically tested. The application to the seismicity of Japan from 1970 to 2003 shows that the new model incorporating the physical concept of the rate-and-state theory performs not worse than the purely stochastic model with two free parameters only. The numerical results obtained in these applications are related to physical characters of the model as the stress change produced by an earthquake close to its edges and to the A and σ parameters of the rate-and-state constitutive law.

  3. Topos models for physics and topos theory

    NASA Astrophysics Data System (ADS)

    Wolters, Sander

    2014-08-01

    What is the role of topos theory in the topos models for quantum theory as used by Isham, Butterfield, Döring, Heunen, Landsman, Spitters, and others? In other words, what is the interplay between physical motivation for the models and the mathematical framework used in these models? Concretely, we show that the presheaf topos model of Butterfield, Isham, and Döring resembles classical physics when viewed from the internal language of the presheaf topos, similar to the copresheaf topos model of Heunen, Landsman, and Spitters. Both the presheaf and copresheaf models provide a "quantum logic" in the form of a complete Heyting algebra. Although these algebras are natural from a topos theoretic stance, we seek a physical interpretation for the logical operations. Finally, we investigate dynamics. In particular, we describe how an automorphism on the operator algebra induces a homeomorphism (or isomorphism of locales) on the associated state spaces of the topos models, and how elementary propositions and truth values transform under the action of this homeomorphism. Also with dynamics the focus is on the internal perspective of the topos.

  4. Topos models for physics and topos theory

    SciTech Connect

    Wolters, Sander

    2014-08-15

    What is the role of topos theory in the topos models for quantum theory as used by Isham, Butterfield, Döring, Heunen, Landsman, Spitters, and others? In other words, what is the interplay between physical motivation for the models and the mathematical framework used in these models? Concretely, we show that the presheaf topos model of Butterfield, Isham, and Döring resembles classical physics when viewed from the internal language of the presheaf topos, similar to the copresheaf topos model of Heunen, Landsman, and Spitters. Both the presheaf and copresheaf models provide a “quantum logic” in the form of a complete Heyting algebra. Although these algebras are natural from a topos theoretic stance, we seek a physical interpretation for the logical operations. Finally, we investigate dynamics. In particular, we describe how an automorphism on the operator algebra induces a homeomorphism (or isomorphism of locales) on the associated state spaces of the topos models, and how elementary propositions and truth values transform under the action of this homeomorphism. Also with dynamics the focus is on the internal perspective of the topos.

  5. Access Nets: Modeling Access to Physical Spaces

    NASA Astrophysics Data System (ADS)

    Frohardt, Robert; Chang, Bor-Yuh Evan; Sankaranarayanan, Sriram

    Electronic, software-managed mechanisms using, for example, radio-frequency identification (RFID) cards, enable great flexibility in specifying access control policies to physical spaces. For example, access rights may vary based on time of day or could differ in normal versus emergency situations. With such fine-grained control, understanding and reasoning about what a policy permits becomes surprisingly difficult requiring knowledge of permission levels, spatial layout, and time. In this paper, we present a formal modeling framework, called AccessNets, suitable for describing a combination of access permissions, physical spaces, and temporal constraints. Furthermore, we provide evidence that model checking techniques are effective in reasoning about physical access control policies. We describe our results from a tool that uses reachability analysis to validate security policies.

  6. Ladder physics in the spin fermion model

    DOE PAGES

    Tsvelik, A. M.

    2017-05-01

    A link is established between the spin fermion (SF) model of the cuprates and the approach based on the analogy between the physics of doped Mott insulators in two dimensions and the physics of fermionic ladders. This enables one to use nonperturbative results derived for fermionic ladders to move beyond the large-N approximation in the SF model. Here, it is shown that the paramagnon exchange postulated in the SF model has exactly the right form to facilitate the emergence of the fully gapped d-Mott state in the region of the Brillouin zone at the hot spots of the Fermi surface.more » Hence, the SF model provides an adequate description of the pseudogap.« less

  7. Physical models of tissue in shear fields.

    PubMed

    Carstensen, Edwin L; Parker, Kevin J

    2014-04-01

    This review considers three general classes of physical as opposed to phenomenological models of the shear elasticity of tissues. The first is simple viscoelasticity. This model has a special role in elastography because it is the language in which experimental and clinical data are communicated. The second class of models involves acoustic relaxation, in which the medium contains inner time-dependent systems that are driven through the external bulk medium. Hysteresis, the phenomenon characterizing the third class of models, involves losses that are related to strain rather than time rate of change of strain. In contrast to the vast efforts given to tissue characterization through their bulk moduli over the last half-century, similar research using low-frequency shear data is in its infancy. Rather than a neat summary of existing facts, this essay is a framework for hypothesis generation-guessing what physical mechanisms give tissues their shear properties.

  8. Dilution physics modeling: Dissolution/precipitation chemistry

    SciTech Connect

    Onishi, Y.; Reid, H.C.; Trent, D.S.

    1995-09-01

    This report documents progress made to date on integrating dilution/precipitation chemistry and new physical models into the TEMPEST thermal-hydraulics computer code. Implementation of dissolution/precipitation chemistry models is necessary for predicting nonhomogeneous, time-dependent, physical/chemical behavior of tank wastes with and without a variety of possible engineered remediation and mitigation activities. Such behavior includes chemical reactions, gas retention, solids resuspension, solids dissolution and generation, solids settling/rising, and convective motion of physical and chemical species. Thus this model development is important from the standpoint of predicting the consequences of various engineered activities, such as mitigation by dilution, retrieval, or pretreatment, that can affect safe operations. The integration of a dissolution/precipitation chemistry module allows the various phase species concentrations to enter into the physical calculations that affect the TEMPEST hydrodynamic flow calculations. The yield strength model of non-Newtonian sludge correlates yield to a power function of solids concentration. Likewise, shear stress is concentration-dependent, and the dissolution/precipitation chemistry calculations develop the species concentration evolution that produces fluid flow resistance changes. Dilution of waste with pure water, molar concentrations of sodium hydroxide, and other chemical streams can be analyzed for the reactive species changes and hydrodynamic flow characteristics.

  9. Mental Models in Expert Physics Reasoning.

    ERIC Educational Resources Information Center

    Roschelle, Jeremy; Greeno, James G.

    Proposed is a relational framework for characterizing experienced physicists' representations of physics problem situations and the process of constructing these representations. A representation includes a coherent set of relations among: (1) a mental model of the objects in the situation, along with their relevant properties and relations; (2) a…

  10. Physical models for classroom teaching in hydrology

    NASA Astrophysics Data System (ADS)

    Rodhe, A.

    2012-09-01

    Hydrology teaching benefits from the fact that many important processes can be illustrated and explained with simple physical models. A set of mobile physical models has been developed and used during many years of lecturing at basic university level teaching in hydrology. One model, with which many phenomena can be demonstrated, consists of a 1.0-m-long plexiglass container containing an about 0.25-m-deep open sand aquifer through which water is circulated. The model can be used for showing the groundwater table and its influence on the water content in the unsaturated zone and for quantitative determination of hydraulic properties such as the storage coefficient and the saturated hydraulic conductivity. It is also well suited for discussions on the runoff process and the significance of recharge and discharge areas for groundwater. The flow paths of water and contaminant dispersion can be illustrated in tracer experiments using fluorescent or colour dye. This and a few other physical models, with suggested demonstrations and experiments, are described in this article. The finding from using models in classroom teaching is that it creates curiosity among the students, promotes discussions and most likely deepens the understanding of the basic processes.

  11. A thermodynamic model of physical gels

    NASA Astrophysics Data System (ADS)

    An, Yonghao; Solis, Francisco J.; Jiang, Hanqing

    2010-12-01

    Physical gels are characterized by dynamic cross-links that are constantly created and broken, changing its state between solid and liquid under influence of environmental factors. This restructuring ability of physical gels makes them an important class of materials with many applications, such as in drug delivery. In this article, we present a thermodynamic model for physical gels that considers both the elastic properties of the network and the transient nature of the cross-links. The cross-links' reformation is captured through a connectivity tensor M at the microscopic level. The macroscopic quantities, such as the volume fraction of the monomer ϕ, number of monomers per cross-link s, and the number of cross-links per volume q, are defined by statistic averaging. A mean-field energy functional for the gel is constructed based on these variables. The equilibrium equations and the stress are obtained at the current state. We study the static thermodynamic properties of physical gels predicted by the model. We discuss the problems of un-constrained swelling and stress driven phase transitions of physical gels and describe the conditions under which these phenomena arise as functions of the bond activation energy Ea, polymer/solvent interaction parameter χ, and external stress p.

  12. Service Learning In Physics: The Consultant Model

    NASA Astrophysics Data System (ADS)

    Guerra, David

    2005-04-01

    Each year thousands of students across the country and across the academic disciplines participate in service learning. Unfortunately, with no clear model for integrating community service into the physics curriculum, there are very few physics students engaged in service learning. To overcome this shortfall, a consultant based service-learning program has been developed and successfully implemented at Saint Anselm College (SAC). As consultants, students in upper level physics courses apply their problem solving skills in the service of others. Most recently, SAC students provided technical and managerial support to a group from Girl's Inc., a national empowerment program for girls in high-risk, underserved areas, who were participating in the national FIRST Lego League Robotics competition. In their role as consultants the SAC students provided technical information through brainstorming sessions and helped the girls stay on task with project management techniques, like milestone charting. This consultant model of service-learning, provides technical support to groups that may not have a great deal of resources and gives physics students a way to improve their interpersonal skills, test their technical expertise, and better define the marketable skill set they are developing through the physics curriculum.

  13. Multiscale physics-based modeling of friction

    NASA Astrophysics Data System (ADS)

    Eriten, Melih

    Frictional contacts between solids exist in nature and in a wide range of engineering applications. Friction causes energy loss, and it is the main source of wear and surface degradation which limits the lifetime of mechanical systems. Yet, friction is needed to walk, run, accelerate, slow down or stop moving systems. Whether desirable or not, friction is a very complex physical phenomenon. The behavior of systems with friction is nonlinear, and the physical mechanisms governing friction behavior span a wide range of spatial and temporal scales. A thorough study of friction should employ experimentalists and theoreticians in chemistry, materials science, tribology, mechanics, dynamics, and structural engineering. High spatial and temporal resolutions are required to capture and model essential physics of a frictional contact. However, such a detailed model is impractical in large-scale structural dynamics simulations; especially since frictional contacts can be numerous in a given application. Reduced-order models (ROMs) achieve broader applicability by compromising several aspects and accounting for the important physics. Hence, rather simple Coulomb friction is still the most ubiquitous model in the modeling and simulation literature. As an alternative, a reduced-order friction model built-up from micromechanics of surfaces is proposed in this work. Continuum-scale formulation of pre-sliding friction behavior is combined with material-strength-based friction coefficients to develop a physics-based friction model at asperity-scale. Then, the statistical summation technique is utilized to build a multiscale modeling framework. A novel joint fretting setup is designed for friction experiments in a practical setting, and the developed models are tested. Both asperity and rough surface friction models show good agreement with experimental data. The influences of materials, surface roughness and contact contamination on the friction are also studied. Finally, the

  14. Transforming teacher knowledge: Modeling instruction in physics

    NASA Astrophysics Data System (ADS)

    Cabot, Lloyd H.

    I show that the Modeling physics curriculum is readily accommodated by most teachers in favor of traditional didactic pedagogies. This is so, at least in part, because Modeling focuses on a small set of connected models embedded in a self-consistent theoretical framework and thus is closely congruent with human cognition in this context which is to generate mental models of physical phenomena as both predictive and explanatory devices. Whether a teacher fully implements the Modeling pedagogy depends on the depth of the teacher's commitment to inquiry-based instruction, specifically Modeling instruction, as a means of promoting student understanding of Newtonian mechanics. Moreover, this commitment trumps all other characteristics: teacher educational background, content coverage issues, student achievement data, district or state learning standards, and district or state student assessments. Indeed, distinctive differences exist in how Modeling teachers deliver their curricula and some teachers are measurably more effective than others in their delivery, but they all share an unshakable belief in the efficacy of inquiry-based, constructivist-oriented instruction. The Modeling Workshops' pedagogy, duration, and social interactions impacts teachers' self-identification as members of a professional community. Finally, I discuss the consequences my research may have for the Modeling Instruction program designers and for designers of professional development programs generally.

  15. Investigations of physical model of biological tissue

    NASA Astrophysics Data System (ADS)

    Linkov, Kirill G.; Kisselev, Gennady L.; Loschenov, Victor B.

    1996-12-01

    Physical model of a biological tissue for comparison with earlier created mathematical model of a biological tissue and researches of distribution photosensitizer in a depth was created and investigated. Mathematical model is based on granulated representation of optical medium. The model of a biological tissue was created on the basis of enough thin layers of a special material. For fluorescence excitation laser sources with a various wavelength were used. For investigation of scattering and fluorescent signal laser- fiber spectrum-analyzer LESA-5 was applied. Water solution of aluminum phthalocyanine and oil solution of zinc phthalocyanine were used for receiving of fluorescent signal. Created samples have certain absorbing and fluorescent properties. Scattering properties of samples are close to scattering properties of real human skin. By virtue of layered structure the model permits to simulate as a biological tissue without photosensitizer accumulation in it, as tissue with photosensitizer accumulation with certain distribution in a depth. Dependence of fields distribution on a surface was investigated at change of parameters of a model. Essential changes of distribution on a surface depending on the characteristics of model was revealed. The space and angular characteristics was investigated also. The investigations with physical model correspond to predicted results of theoretical model.

  16. Modelling Students' Construction of Energy Models in Physics.

    ERIC Educational Resources Information Center

    Devi, Roshni; And Others

    1996-01-01

    Examines students' construction of experimentation models for physics theories in energy storage, transformation, and transfers involving electricity and mechanics. Student problem solving dialogs and artificial intelligence modeling of these processes is analyzed. Construction of models established relations between elements with linear causal…

  17. Modelling Students' Construction of Energy Models in Physics.

    ERIC Educational Resources Information Center

    Devi, Roshni; And Others

    1996-01-01

    Examines students' construction of experimentation models for physics theories in energy storage, transformation, and transfers involving electricity and mechanics. Student problem solving dialogs and artificial intelligence modeling of these processes is analyzed. Construction of models established relations between elements with linear causal…

  18. Physics Beyond the Standard Model at Colliders

    NASA Astrophysics Data System (ADS)

    Matchev, Konstantin

    These lectures introduce the modern machinery used in searches and studies of new physics Beyond the Standard Model (BSM) at colliders. The first lecture provides an overview of the main simulation tools used in high energy physics, including automated parton-level calculators, general purpose event generators, detector simulators, etc. The second lecture is a brief introduction to low energy supersymmetry (SUSY) as a representative BSM paradigm. The third lecture discusses the main collider signatures of SUSY and methods for measuring the masses of new particles in events with missing energy.

  19. Modeling quantum physics with machine learning

    NASA Astrophysics Data System (ADS)

    Lopez-Bezanilla, Alejandro; Arsenault, Louis-Francois; Millis, Andrew; Littlewood, Peter; von Lilienfeld, Anatole

    2014-03-01

    Machine Learning (ML) is a systematic way of inferring new results from sparse information. It directly allows for the resolution of computationally expensive sets of equations by making sense of accumulated knowledge and it is therefore an attractive method for providing computationally inexpensive 'solvers' for some of the important systems of condensed matter physics. In this talk a non-linear regression statistical model is introduced to demonstrate the utility of ML methods in solving quantum physics related problem, and is applied to the calculation of electronic transport in 1D channels. DOE contract number DE-AC02-06CH11357.

  20. Physics Beyond the Standard Model: Supersymmetry

    SciTech Connect

    Nojiri, M.M.; Plehn, T.; Polesello, G.; Alexander, John M.; Allanach, B.C.; Barr, Alan J.; Benakli, K.; Boudjema, F.; Freitas, A.; Gwenlan, C.; Jager, S.; /CERN /LPSC, Grenoble

    2008-02-01

    This collection of studies on new physics at the LHC constitutes the report of the supersymmetry working group at the Workshop 'Physics at TeV Colliders', Les Houches, France, 2007. They cover the wide spectrum of phenomenology in the LHC era, from alternative models and signatures to the extraction of relevant observables, the study of the MSSM parameter space and finally to the interplay of LHC observations with additional data expected on a similar time scale. The special feature of this collection is that while not each of the studies is explicitly performed together by theoretical and experimental LHC physicists, all of them were inspired by and discussed in this particular environment.

  1. Modelling the Physical System of Belawan Estuary

    NASA Astrophysics Data System (ADS)

    Tarigan, A. P. M.; Swandana, D.; Isma, F.

    2017-03-01

    Belawan estuary represents one of the most complex and fascinating mixed environments of sea and land, where not only habitat of rich biodiversity but also international seaport infrastructure are at stake. It is therefore a matter of considerable importance to understand the physical system which characterizes the dynamics of the estuarine water. The purpose of this study is to model the changing water depths, tidal currents, salt, temperature and sediment concentration over a long stretch of Belawan estuary on an hourly basis. The first essential step is to define the bathymetry based on which other physical parameters are simulated. The study is accomplished by building working computer modules which simplify and model the systems complexities. It should be noted that model validation and improvement is the subject of the next study.

  2. Evaluation of Monte Carlo tools for high energy atmospheric physics

    NASA Astrophysics Data System (ADS)

    Rutjes, Casper; Sarria, David; Broberg Skeltved, Alexander; Luque, Alejandro; Diniz, Gabriel; Østgaard, Nikolai; Ebert, Ute

    2016-11-01

    The emerging field of high energy atmospheric physics (HEAP) includes terrestrial gamma-ray flashes, electron-positron beams and gamma-ray glows from thunderstorms. Similar emissions of high energy particles occur in pulsed high voltage discharges. Understanding these phenomena requires appropriate models for the interaction of electrons, positrons and photons of up to 40 MeV energy with atmospheric air. In this paper, we benchmark the performance of the Monte Carlo codes Geant4, EGS5 and FLUKA developed in other fields of physics and of the custom-made codes GRRR and MC-PEPTITA against each other within the parameter regime relevant for high energy atmospheric physics. We focus on basic tests, namely on the evolution of monoenergetic and directed beams of electrons, positrons and photons with kinetic energies between 100 keV and 40 MeV through homogeneous air in the absence of electric and magnetic fields, using a low energy cutoff of 50 keV. We discuss important differences between the results of the different codes and provide plausible explanations. We also test the computational performance of the codes. The Supplement contains all results, providing a first benchmark for present and future custom-made codes that are more flexible in including electrodynamic interactions.

  3. Prototyping of cerebral vasculature physical models.

    PubMed

    Khan, Imad S; Kelly, Patrick D; Singer, Robert J

    2014-01-01

    Prototyping of cerebral vasculature models through stereolithographic methods have the ability to accurately depict the 3D structures of complicated aneurysms with high accuracy. We describe the method to manufacture such a model and review some of its uses in the context of treatment planning, research, and surgical training. We prospectively used the data from the rotational angiography of a 40-year-old female who presented with an unruptured right paraclinoid aneurysm. The 3D virtual model was then converted to a physical life-sized model. The model constructed was shown to be a very accurate depiction of the aneurysm and its associated vasculature. It was found to be useful, among other things, for surgical training and as a patient education tool. With improving and more widespread printing options, these models have the potential to become an important part of research and training modalities.

  4. Testing Physical Models of Passive Membrane Permeation

    PubMed Central

    Leung, Siegfried S. F.; Mijalkovic, Jona; Borrelli, Kenneth; Jacobson, Matthew P.

    2012-01-01

    The biophysical basis of passive membrane permeability is well understood, but most methods for predicting membrane permeability in the context of drug design are based on statistical relationships that indirectly capture the key physical aspects. Here, we investigate molecular mechanics-based models of passive membrane permeability and evaluate their performance against different types of experimental data, including parallel artificial membrane permeability assays (PAMPA), cell-based assays, in vivo measurements, and other in silico predictions. The experimental data sets we use in these tests are diverse, including peptidomimetics, congeneric series, and diverse FDA approved drugs. The physical models are not specifically trained for any of these data sets; rather, input parameters are based on standard molecular mechanics force fields, such as partial charges, and an implicit solvent model. A systematic approach is taken to analyze the contribution from each component in the physics-based permeability model. A primary factor in determining rates of passive membrane permeation is the conformation-dependent free energy of desolvating the molecule, and this measure alone provides good agreement with experimental permeability measurements in many cases. Other factors that improve agreement with experimental data include deionization and estimates of entropy losses of the ligand and the membrane, which lead to size-dependence of the permeation rate. PMID:22621168

  5. Physical modeling of the composting ecosystem.

    PubMed

    Hogan, J A; Miller, F C; Finstein, M S

    1989-05-01

    A composting physical model with an experimental chamber with a working volume of 14 x 10 cm (0.5 ft) was designed to avoid exaggerated conductive heat loss resulting from, relative to field-scale piles, a disproportionately large outer surface-area-to-volume ratio. In the physical model, conductive flux (rate of heat flow through chamber surfaces) was made constant and slight through a combination of insulation and temperature control of the surrounding air. This control was based on the instantaneous conductive flux, as calculated from temperature differentials via a conductive heat flow model. An experiment was performed over a 10-day period in which control of the composting process was based on ventilative heat removal in reference to a microbially favorable temperature ceiling (temperature feedback). By using the conduction control system (surrounding air temperature controlled), 2.4% of the total heat evolved from the chamber was through conduction, whereas the remainder was through the ventilative mechanisms of the latent heat of vaporization and the sensible temperature increase of air. By comparison, with insulation alone (the conduction control system was not used) conduction accounted for 33.5% of the total heat evolved. This difference in conduction resulted in substantial behavioral differences with respect to the temperature of the composting matrix and the amount of water removed. By emphasizing the slight conduction system (2.4% of total heat flow) as being a better representative of field conditions, a comparison was made between composting system behavior in the laboratory physical model and field-scale piles described in earlier reports. Numerous behavioral patterns were qualitatively similar in the laboratory and field (e.g., temperature gradient, O(2) content, and water removal). It was concluded that field-scale composting system behavior can be simulated reasonably faithfully in the physical model.

  6. Electromagnetic Physics Models for Parallel Computing Architectures

    NASA Astrophysics Data System (ADS)

    Amadio, G.; Ananya, A.; Apostolakis, J.; Aurora, A.; Bandieramonte, M.; Bhattacharyya, A.; Bianchini, C.; Brun, R.; Canal, P.; Carminati, F.; Duhem, L.; Elvira, D.; Gheata, A.; Gheata, M.; Goulas, I.; Iope, R.; Jun, S. Y.; Lima, G.; Mohanty, A.; Nikitina, T.; Novak, M.; Pokorski, W.; Ribon, A.; Seghal, R.; Shadura, O.; Vallecorsa, S.; Wenzel, S.; Zhang, Y.

    2016-10-01

    The recent emergence of hardware architectures characterized by many-core or accelerated processors has opened new opportunities for concurrent programming models taking advantage of both SIMD and SIMT architectures. GeantV, a next generation detector simulation, has been designed to exploit both the vector capability of mainstream CPUs and multi-threading capabilities of coprocessors including NVidia GPUs and Intel Xeon Phi. The characteristics of these architectures are very different in terms of the vectorization depth and type of parallelization needed to achieve optimal performance. In this paper we describe implementation of electromagnetic physics models developed for parallel computing architectures as a part of the GeantV project. Results of preliminary performance evaluation and physics validation are presented as well.

  7. Electromagnetic physics models for parallel computing architectures

    DOE PAGES

    Amadio, G.; Ananya, A.; Apostolakis, J.; ...

    2016-11-21

    The recent emergence of hardware architectures characterized by many-core or accelerated processors has opened new opportunities for concurrent programming models taking advantage of both SIMD and SIMT architectures. GeantV, a next generation detector simulation, has been designed to exploit both the vector capability of mainstream CPUs and multi-threading capabilities of coprocessors including NVidia GPUs and Intel Xeon Phi. The characteristics of these architectures are very different in terms of the vectorization depth and type of parallelization needed to achieve optimal performance. In this paper we describe implementation of electromagnetic physics models developed for parallel computing architectures as a part ofmore » the GeantV project. Finally, the results of preliminary performance evaluation and physics validation are presented as well.« less

  8. Electromagnetic physics models for parallel computing architectures

    SciTech Connect

    Amadio, G.; Ananya, A.; Apostolakis, J.; Aurora, A.; Bandieramonte, M.; Bhattacharyya, A.; Bianchini, C.; Brun, R.; Canal, P.; Carminati, F.; Duhem, L.; Elvira, D.; Gheata, A.; Gheata, M.; Goulas, I.; Iope, R.; Jun, S. Y.; Lima, G.; Mohanty, A.; Nikitina, T.; Novak, M.; Pokorski, W.; Ribon, A.; Seghal, R.; Shadura, O.; Vallecorsa, S.; Wenzel, S.; Zhang, Y.

    2016-11-21

    The recent emergence of hardware architectures characterized by many-core or accelerated processors has opened new opportunities for concurrent programming models taking advantage of both SIMD and SIMT architectures. GeantV, a next generation detector simulation, has been designed to exploit both the vector capability of mainstream CPUs and multi-threading capabilities of coprocessors including NVidia GPUs and Intel Xeon Phi. The characteristics of these architectures are very different in terms of the vectorization depth and type of parallelization needed to achieve optimal performance. In this paper we describe implementation of electromagnetic physics models developed for parallel computing architectures as a part of the GeantV project. Finally, the results of preliminary performance evaluation and physics validation are presented as well.

  9. Statistical Physics of Pairwise Probability Models

    PubMed Central

    Roudi, Yasser; Aurell, Erik; Hertz, John A.

    2009-01-01

    Statistical models for describing the probability distribution over the states of biological systems are commonly used for dimensional reduction. Among these models, pairwise models are very attractive in part because they can be fit using a reasonable amount of data: knowledge of the mean values and correlations between pairs of elements in the system is sufficient. Not surprisingly, then, using pairwise models for studying neural data has been the focus of many studies in recent years. In this paper, we describe how tools from statistical physics can be employed for studying and using pairwise models. We build on our previous work on the subject and study the relation between different methods for fitting these models and evaluating their quality. In particular, using data from simulated cortical networks we study how the quality of various approximate methods for inferring the parameters in a pairwise model depends on the time bin chosen for binning the data. We also study the effect of the size of the time bin on the model quality itself, again using simulated data. We show that using finer time bins increases the quality of the pairwise model. We offer new ways of deriving the expressions reported in our previous work for assessing the quality of pairwise models. PMID:19949460

  10. Video Analysis and Modeling in Physics Education

    NASA Astrophysics Data System (ADS)

    Brown, Doug

    2008-03-01

    The Tracker video analysis program allows users to overlay simple dynamical models on a video clip. Video modeling offers advantages over both traditional video analysis and animation-only modeling. In traditional video analysis, for example, students measure ``g'' by tracking a dropped or tossed ball, constructing a position or velocity vs. time graph, and interpreting the graphs to obtain initial conditions and acceleration. In video modeling, by contrast, the students interactively construct theoretical force expressions and define initial conditions for a dynamical particle model that synchs with and draws itself on the video. The behavior of the model is thus compared directly with that of the real-world motion. Tracker uses the Open Source Physics code library so sophisticated models are possible. I will demonstrate and compare video modeling with video analysis and I will discuss the advantages of video modeling over animation-only modeling. The Tracker video analysis program is available at: http://www.cabrillo.edu/˜dbrown/tracker/.

  11. Generomak: Fusion physics, engineering and costing model

    SciTech Connect

    Delene, J.G.; Krakowski, R.A.; Sheffield, J.; Dory, R.A.

    1988-06-01

    A generic fusion physics, engineering and economics model (Generomak) was developed as a means of performing consistent analysis of the economic viability of alternative magnetic fusion reactors. The original Generomak model developed at Oak Ridge by Sheffield was expanded for the analyses of the Senior Committee on Environmental Safety and Economics of Magnetic Fusion Energy (ESECOM). This report describes the Generomak code as used by ESECOM. The input data used for each of the ten ESECOM fusion plants and the Generomak code output for each case is given. 14 refs., 3 figs., 17 tabs.

  12. Physical models of polarization mode dispersion

    SciTech Connect

    Menyuk, C.R.; Wai, P.K.A.

    1995-12-31

    The effect of randomly varying birefringence on light propagation in optical fibers is studied theoretically in the parameter regime that will be used for long-distance communications. In this regime, the birefringence is large and varies very rapidly in comparison to the nonlinear and dispersive scale lengths. We determine the polarization mode dispersion, and we show that physically realistic models yield the same result for polarization mode dispersion as earlier heuristic models that were introduced by Poole. We also prove an ergodic theorem.

  13. Statistical physical models of cellular motility

    NASA Astrophysics Data System (ADS)

    Banigan, Edward J.

    Cellular motility is required for a wide range of biological behaviors and functions, and the topic poses a number of interesting physical questions. In this work, we construct and analyze models of various aspects of cellular motility using tools and ideas from statistical physics. We begin with a Brownian dynamics model for actin-polymerization-driven motility, which is responsible for cell crawling and "rocketing" motility of pathogens. Within this model, we explore the robustness of self-diffusiophoresis, which is a general mechanism of motility. Using this mechanism, an object such as a cell catalyzes a reaction that generates a steady-state concentration gradient that propels the object in a particular direction. We then apply these ideas to a model for depolymerization-driven motility during bacterial chromosome segregation. We find that depolymerization and protein-protein binding interactions alone are sufficient to robustly pull a chromosome, even against large loads. Next, we investigate how forces and kinetics interact during eukaryotic mitosis with a many-microtubule model. Microtubules exert forces on chromosomes, but since individual microtubules grow and shrink in a force-dependent way, these forces lead to bistable collective microtubule dynamics, which provides a mechanism for chromosome oscillations and microtubule-based tension sensing. Finally, we explore kinematic aspects of cell motility in the context of the immune system. We develop quantitative methods for analyzing cell migration statistics collected during imaging experiments. We find that during chronic infection in the brain, T cells run and pause stochastically, following the statistics of a generalized Levy walk. These statistics may contribute to immune function by mimicking an evolutionarily conserved efficient search strategy. Additionally, we find that naive T cells migrating in lymph nodes also obey non-Gaussian statistics. Altogether, our work demonstrates how physical

  14. Physical Modelling of the Zodiacal Dust Cloud

    NASA Astrophysics Data System (ADS)

    Ozernoy, L. M.

    2001-01-01

    This review is based on an extensive work aimed at the physical modeling of the interplanetary dust (IPD) cloud, i.e. establishing a link between the observable characteristics of the zodiacal cloud and the dynamical and physical properties of the parent minor bodies of the Solar System, which has been done in collaboration with N. Gorkavyi, J. Mather, and T. Taidakova. We use a new computational approach proposed by the authors, which makes it possible to elaborate high-quality 3D models of the IPD cloud with the number of particle positions in each model as high as 1010-11. This approach enables us to simulate the distribution of the major sources of dust in the Solar System. In particular, they include 20-30 million cold comets gravitationally scattered by the four giant planets in cometary journey from the Kuiper belt inward in the Solar System. These comets are found to be distributed in the form of four `cometary belts' associated with the orbits of the giant planets. Our 3D physical model of the IPD cloud, which includes three dust components -- asteroidal, cometary, and kuiperoidal, explains three different kinds of data: (i) the distribution of sources of dust, both known and predicted to exist from computer simulations; (ii) zodiacal light distribution in the Solar System, which fits the COBE data with an average accuracy of 0.85%; and (iii) the experimental data of Pioneers and Voyagers dust detectors. Further improvements of our modeling and their importance for astronomy and cosmology are outlined.

  15. Improving the physics models in the Space Weather Modeling Framework

    NASA Astrophysics Data System (ADS)

    Toth, G.; Fang, F.; Frazin, R. A.; Gombosi, T. I.; Ilie, R.; Liemohn, M. W.; Manchester, W. B.; Meng, X.; Pawlowski, D. J.; Ridley, A. J.; Sokolov, I.; van der Holst, B.; Vichare, G.; Yigit, E.; Yu, Y.; Buzulukova, N.; Fok, M. H.; Glocer, A.; Jordanova, V. K.; Welling, D. T.; Zaharia, S. G.

    2010-12-01

    The success of physics based space weather forecasting depends on several factors: we need sufficient amount and quality of timely observational data, we have to understand the physics of the Sun-Earth system well enough, we need sophisticated computational models, and the models have to run faster than real time on the available computational resources. This presentation will focus on a single ingredient, the recent improvements of the mathematical and numerical models in the Space Weather Modeling Framework. We have developed a new physics based CME initiation code using flux emergence from the convection zone solving the equations of radiative magnetohydrodynamics (MHD). Our new lower corona and solar corona models use electron heat conduction, Alfven wave heating, and boundary conditions based on solar tomography. We can obtain a physically consistent solar wind model from the surface of the Sun all the way to the L1 point without artificially changing the polytropic index. The global magnetosphere model can now solve the multi-ion MHD equations and take into account the oxygen outflow from the polar wind model. We have also added the options of solving for Hall MHD and anisotropic pressure. Several new inner magnetosphere models have been added to the framework: CRCM, HEIDI and RAM-SCB. These new models resolve the pitch angle distribution of the trapped particles. The upper atmosphere model GITM has been improved by including a self-consistent equatorial electrodynamics and the effects of solar flares. This presentation will very briefly describe the developments and highlight some results obtained with the improved and new models.

  16. Models in Physics, Models for Physics Learning, and Why the Distinction May Matter in the Case of Electric Circuits

    ERIC Educational Resources Information Center

    Hart, Christina

    2008-01-01

    Models are important both in the development of physics itself and in teaching physics. Historically, the consensus models of physics have come to embody particular ontological assumptions and epistemological commitments. Educators have generally assumed that the consensus models of physics, which have stood the test of time, will also work well…

  17. Models in Physics, Models for Physics Learning, and Why the Distinction May Matter in the Case of Electric Circuits

    ERIC Educational Resources Information Center

    Hart, Christina

    2008-01-01

    Models are important both in the development of physics itself and in teaching physics. Historically, the consensus models of physics have come to embody particular ontological assumptions and epistemological commitments. Educators have generally assumed that the consensus models of physics, which have stood the test of time, will also work well…

  18. Shape Models and Physical Properties of Asteroids

    NASA Astrophysics Data System (ADS)

    Santana-Ros, T.; Dudziński, G.; Bartczak, P.

    Despite the large amount of high quality data generated in recent space encounters with asteroids, the majority of our knowledge about these objects comes from ground based observations. Asteroids travelling in orbits that are potentially hazardous for the Earth form an especially interesting group to be studied. In order to predict their orbital evolution, it is necessary to investigate their physical properties. This paper briefly describes the data requirements and different techniques used to solve the lightcurve inversion problem. Although photometry is the most abundant type of observational data, models of asteroids can be obtained using various data types and techniques. We describe the potential of radar imaging and stellar occultation timings to be combined with disk-integrated photometry in order to reveal information about physical properties of asteroids.

  19. Beyond the standard model of particle physics.

    PubMed

    Virdee, T S

    2016-08-28

    The Large Hadron Collider (LHC) at CERN and its experiments were conceived to tackle open questions in particle physics. The mechanism of the generation of mass of fundamental particles has been elucidated with the discovery of the Higgs boson. It is clear that the standard model is not the final theory. The open questions still awaiting clues or answers, from the LHC and other experiments, include: What is the composition of dark matter and of dark energy? Why is there more matter than anti-matter? Are there more space dimensions than the familiar three? What is the path to the unification of all the fundamental forces? This talk will discuss the status of, and prospects for, the search for new particles, symmetries and forces in order to address the open questions.This article is part of the themed issue 'Unifying physics and technology in light of Maxwell's equations'.

  20. Dissecting new physics models through kinematic edges

    NASA Astrophysics Data System (ADS)

    Iyer, Abhishek M.; Maitra, Ushoshi

    2017-02-01

    Kinematic edges in the invariant mass distributions of different final state particles are typically a signal of new physics. In this work we propose a scenario wherein these edges could be utilized in discriminating between different classes of models. To this effect, we consider the resonant production of a heavy Higgs like resonance (H1) as a case study. Such states are a characteristic feature of many new physics scenarios beyond the standard model (SM). In the event of a discovery, it is essential to identify the true nature of the underlying theory. In this work we propose a channel, H1→t2t , where t2 is a vectorlike gauge singlet top-partner that decays into W b , Z t , h t . Invariant mass distributions constructed out of these final states are characterized by the presence of kinematic edges, which are unique to the topology under consideration. Further, since all the final state particles are SM states, the position in the edges of these invariant mass distributions can be used to exclusively determine the masses of the resonances. Observation of these features are meant to serve as a trigger, thereby mandating a more detailed analysis in a particular direction of parameter space. The absence of these edge like features, in the specific invariant mass distributions considered here, in minimal versions of supersymmetric models (MSSM) also serves as a harbinger of such non-MSSM-like scenarios.

  1. Physical model for membrane protrusions during spreading

    PubMed Central

    Chamaraux, François; Ali, Olivier; Keller, Sébastien; Bruckert, Franz; Fourcade, Bertrand

    2008-01-01

    During cell spreading onto a substrate, the kinetics of the contact area is an observable quantity. This paper is concerned with a physical approach to model this process in the case of ameboid motility where the membrane detaches itself from the underlying cytoskeleton at the leading edge. The physical model we propose is based on previous reports which point out that membrane tension regulates cell spreading. Using a phenomenological feedback loop to mimic stress dependent biochemistry, we show that the actin polymerisation rate can be coupled to the stress which builds up at the margin of the contact area between the cell and the substrate. In the limit of small variation of membrane tension, we show that the actin polymerisation rate can be written in closed form. Our analysis defines characteristic lengths which depend on elastic properties of the membrane-cytoskeleton complex, such as the membrane-cytoskeleton interaction, and on molecular parameters, such as the rate of actin polymerisation. We discuss our model in the case of axi-symmetric and non axi-symmetric spreading and we compute the characteristic time scales as a function of fundamental elastic constants such as the strength of membrane-cytoskeleton adherence. PMID:18824791

  2. Multiscale Atmospheric Physics Modeled by Cumulant Expansions

    NASA Astrophysics Data System (ADS)

    Marston, Brad; Chini, Greg

    2014-03-01

    We investigate a systematic and physically based approach to modeling subgrid physics statistically with the use of an expansion in equal-time cumulants. To accomplish this we replace the zonal average employed in previous work with a low-pass filter that separates small and large scales in the zonal direction. The statistics are non-local, inhomogeneous, and anisotropic; the sole approximation is the neglect of 3-point and higher correlation functions. The closure respects the conservation of energy, enstrophy, and angular momentum. An advantage of the formulation is that correlations between large and small scale processes are treated explicitly without the introduction of phenomenological parameterizations. The approach is tested against full numerical simulation of idealized 1- and 2-layer models of the atmospheric general circulation and shown to yield accurate low-order statistics. (The computer model used to perform these tests runs on OS X and is publicly available.) We identify important multiscale interactions and discuss the computational cost of the new scheme. Supported in part by NSF DMR-1306806 and CCF-1048701.

  3. Pre-Service Physics Teachers' Argumentation in a Model Rocketry Physics Experience

    ERIC Educational Resources Information Center

    Gürel, Cem; Süzük, Erol

    2017-01-01

    This study investigates the quality of argumentation developed by a group of pre-service physics teachers' (PSPT) as an indicator of subject matter knowledge on model rocketry physics. The structure of arguments and scientific credibility model was used as a design framework in the study. The inquiry of model rocketry physics was employed in…

  4. Approximate input physics for stellar modelling

    NASA Astrophysics Data System (ADS)

    Pols, Onno R.; Tout, Christopher A.; Eggleton, Peter P.; Han, Zhanwen

    1995-06-01

    We present a simple and efficient, yet reasonably accurate, equation of state, which at the moderately low temperatures and high densities found in the interiors of stars less massive than the Sun is substantially more accurate than its predecessor by Eggleton, Faulkner & Flannery. Along with the most recently available values in tabular form of opacities, neutrino loss rates, and nuclear reaction rates for a selection of the most important reactions, this provides a convenient package of input physics for stellar modelling. We briefly discuss a few results obtained with the updated stellar evolution code.

  5. Physical model studies of water column separation

    NASA Astrophysics Data System (ADS)

    Autrique, R.; Rodal, E.; Sánchez, A.; Carmona, L.

    2012-11-01

    Results of physical model studies of water column separation following an upstream valve closure in a horizontal pipe are presented, using three dimensionless parameters: the magnitude of the transient, M, or the ratio between the Joukowsky pressure and the initial absolute head; ΔHr, or the ratio between the maximum overpressure and the Joukowsky pressure, and tcr, the duration of the vapor cavity relative to the pipeline period. Conclusions are derived, aiming to a better understanding of water column separation extreme pressures and to the establishment of useful preliminary design guidelines.

  6. Physical modeling synthesis of recorder sound

    NASA Astrophysics Data System (ADS)

    Shiraiwa, Hiroko; Kishi, Kenshi; Nakamura, Isao

    2003-04-01

    A time-domain simulation of the soprano baroque recorder based on the digital waveguide model (DWM) and an air reed model is introduced. The air reed model is developed upon the negative acoustic displacement model (NADM), which was proposed for the organ flue-pipe simulation [Adachi, Proc. of ISMA 1997, pp. 251-260], based on the semiempirical model by Fletcher [Fletcher and Rossing, The Physics of Musical Instruments, 2nd ed. (Springer, Berlin, 2000)]. Two models are proposed to couple DWM and NADM. The jet amplification coefficient is remodeled for the application of NADM for the recorder, regarding the recent experimental reports [Yoshikawa and Arimoto, Proc. of ISMA 2001, pp. 309-312]. The simulation results are presented in terms of the mode transient characteristics and the spectral characteristics of the synthesized sounds. They indicate that the NADM is not sufficient to describe the realistic mode transient of the recorder, while the synthesized sounds maintained almost resemble timbre to the recorder sounds.

  7. Modelling biological complexity: a physical scientist's perspective.

    PubMed

    Coveney, Peter V; Fowler, Philip W

    2005-09-22

    We discuss the modern approaches of complexity and self-organization to understanding dynamical systems and how these concepts can inform current interest in systems biology. From the perspective of a physical scientist, it is especially interesting to examine how the differing weights given to philosophies of science in the physical and biological sciences impact the application of the study of complexity. We briefly describe how the dynamics of the heart and circadian rhythms, canonical examples of systems biology, are modelled by sets of nonlinear coupled differential equations, which have to be solved numerically. A major difficulty with this approach is that all the parameters within these equations are not usually known. Coupled models that include biomolecular detail could help solve this problem. Coupling models across large ranges of length- and time-scales is central to describing complex systems and therefore to biology. Such coupling may be performed in at least two different ways, which we refer to as hierarchical and hybrid multiscale modelling. While limited progress has been made in the former case, the latter is only beginning to be addressed systematically. These modelling methods are expected to bring numerous benefits to biology, for example, the properties of a system could be studied over a wider range of length- and time-scales, a key aim of systems biology. Multiscale models couple behaviour at the molecular biological level to that at the cellular level, thereby providing a route for calculating many unknown parameters as well as investigating the effects at, for example, the cellular level, of small changes at the biomolecular level, such as a genetic mutation or the presence of a drug. The modelling and simulation of biomolecular systems is itself very computationally intensive; we describe a recently developed hybrid continuum-molecular model, HybridMD, and its associated molecular insertion algorithm, which point the way towards the

  8. Modelling biological complexity: a physical scientist's perspective

    PubMed Central

    Coveney, Peter V; Fowler, Philip W

    2005-01-01

    We discuss the modern approaches of complexity and self-organization to understanding dynamical systems and how these concepts can inform current interest in systems biology. From the perspective of a physical scientist, it is especially interesting to examine how the differing weights given to philosophies of science in the physical and biological sciences impact the application of the study of complexity. We briefly describe how the dynamics of the heart and circadian rhythms, canonical examples of systems biology, are modelled by sets of nonlinear coupled differential equations, which have to be solved numerically. A major difficulty with this approach is that all the parameters within these equations are not usually known. Coupled models that include biomolecular detail could help solve this problem. Coupling models across large ranges of length- and time-scales is central to describing complex systems and therefore to biology. Such coupling may be performed in at least two different ways, which we refer to as hierarchical and hybrid multiscale modelling. While limited progress has been made in the former case, the latter is only beginning to be addressed systematically. These modelling methods are expected to bring numerous benefits to biology, for example, the properties of a system could be studied over a wider range of length- and time-scales, a key aim of systems biology. Multiscale models couple behaviour at the molecular biological level to that at the cellular level, thereby providing a route for calculating many unknown parameters as well as investigating the effects at, for example, the cellular level, of small changes at the biomolecular level, such as a genetic mutation or the presence of a drug. The modelling and simulation of biomolecular systems is itself very computationally intensive; we describe a recently developed hybrid continuum-molecular model, HybridMD, and its associated molecular insertion algorithm, which point the way towards the

  9. Detailed Physical Trough Model for NREL's Solar Advisor Model: Preprint

    SciTech Connect

    Wagner, M. J.; Blair, N.; Dobos, A.

    2010-10-01

    Solar Advisor Model (SAM) is a free software package made available by the National Renewable Energy Laboratory (NREL), Sandia National Laboratory, and the US Department of Energy. SAM contains hourly system performance and economic models for concentrating solar power (CSP) systems, photovoltaic, solar hot-water, and generic fuel-use technologies. Versions of SAM prior to 2010 included only the parabolic trough model based on Excelergy. This model uses top-level empirical performance curves to characterize plant behavior, and thus is limited in predictive capability for new technologies or component configurations. To address this and other functionality challenges, a new trough model; derived from physical first principles was commissioned to supplement the Excelergy-based empirical model. This new 'physical model' approaches the task of characterizing the performance of the whole parabolic trough plant by replacing empirical curve-fit relationships with more detailed calculations where practical. The resulting model matches the annual performance of the SAM empirical model (which has been previously verified with plant data) while maintaining run-times compatible with parametric analysis, adding additional flexibility in modeled system configurations, and providing more detailed performance calculations in the solar field, power block, piping, and storage subsystems.

  10. Physics model for wringing of wet cloth

    NASA Astrophysics Data System (ADS)

    Dany Rahmayanti, Handika; Utami, Fisca Dian; Abdullah, Mikrajuddin

    2016-11-01

    One activity that has been performed by human beings for a long time is washing clothes. Before the invention of the washing machine, clothes were washed by hand and then wrung before drying in the open air. When observed carefully, the wringing of cloth presents some interesting phenomena. However, there are no reports on the physical modelling of this very old activity. This paper reports a simple model to explain the discharge of water from clothes when squeezed. A simple tool was also designed to retrieve data to confirm the theory. We found that the theoretical predictions accurately explained the experimental results. The experiments were conducted on two types of cloth: towels and batik cloth. We also obtained a universal curve to which all the data converged.

  11. High precision modeling for fundamental physics experiments

    NASA Astrophysics Data System (ADS)

    Rievers, Benny; Nesemann, Leo; Costea, Adrian; Andres, Michael; Stephan, Ernst P.; Laemmerzahl, Claus

    With growing experimental accuracies and high precision requirements for fundamental physics space missions the needs for accurate numerical modeling techniques are increasing. Motivated by the challenge of length stability in cavities and optical resonators we propose the develop-ment of a high precision modeling tool for the simulation of thermomechanical effects up to a numerical precision of 10-20 . Exemplary calculations for simplified test cases demonstrate the general feasibility of high precision calculations and point out the high complexity of the task. A tool for high precision analysis of complex geometries will have to use new data types, advanced FE solver routines and implement new methods for the evaluation of numerical precision.

  12. Semi-Empirical Modeling of SLD Physics

    NASA Technical Reports Server (NTRS)

    Wright, William B.; Potapczuk, Mark G.

    2004-01-01

    The effects of supercooled large droplets (SLD) in icing have been an area of much interest in recent years. As part of this effort, the assumptions used for ice accretion software have been reviewed. A literature search was performed to determine advances from other areas of research that could be readily incorporated. Experimental data in the SLD regime was also analyzed. A semi-empirical computational model is presented which incorporates first order physical effects of large droplet phenomena into icing software. This model has been added to the LEWICE software. Comparisons are then made to SLD experimental data that has been collected to date. Results will be presented for the comparison of water collection efficiency, ice shape and ice mass.

  13. Tutorial: Physics and modeling of Hall thrusters

    NASA Astrophysics Data System (ADS)

    Boeuf, Jean-Pierre

    2017-01-01

    Hall thrusters are very efficient and competitive electric propulsion devices for satellites and are currently in use in a number of telecommunications and government spacecraft. Their power spans from 100 W to 20 kW, with thrust between a few mN and 1 N and specific impulse values between 1000 and 3000 s. The basic idea of Hall thrusters consists in generating a large local electric field in a plasma by using a transverse magnetic field to reduce the electron conductivity. This electric field can extract positive ions from the plasma and accelerate them to high velocity without extracting grids, providing the thrust. These principles are simple in appearance but the physics of Hall thrusters is very intricate and non-linear because of the complex electron transport across the magnetic field and its coupling with the electric field and the neutral atom density. This paper describes the basic physics of Hall thrusters and gives a (non-exhaustive) summary of the research efforts that have been devoted to the modelling and understanding of these devices in the last 20 years. Although the predictive capabilities of the models are still not sufficient for a full computer aided design of Hall thrusters, significant progress has been made in the qualitative and quantitative understanding of these devices.

  14. Physics-based models of the plasmasphere

    SciTech Connect

    Jordanova, Vania K; Pierrard, Vivane; Goldstein, Jerry; Andr'e, Nicolas; Lemaire, Joseph F; Liemohn, Mike W; Matsui, H

    2008-01-01

    We describe recent progress in physics-based models of the plasmasphere using the Auid and the kinetic approaches. Global modeling of the dynamics and inAuence of the plasmasphere is presented. Results from global plasmasphere simulations are used to understand and quantify (i) the electric potential pattern and evolution during geomagnetic storms, and (ii) the inAuence of the plasmasphere on the excitation of electromagnetic ion cyclotron (ElvIIC) waves a.nd precipitation of energetic ions in the inner magnetosphere. The interactions of the plasmasphere with the ionosphere a.nd the other regions of the magnetosphere are pointed out. We show the results of simulations for the formation of the plasmapause and discuss the inAuence of plasmaspheric wind and of ultra low frequency (ULF) waves for transport of plasmaspheric material. Theoretical formulations used to model the electric field and plasma distribution in the plasmasphere are given. Model predictions are compared to recent CLUSTER and MAGE observations, but also to results of earlier models and satellite observations.

  15. 3-D physical models of amitosis (cytokinesis).

    PubMed

    Cheng, Kang; Zou, Changhua

    2005-01-01

    Based on Newton's laws, extended Coulomb's law and published biological data, we develop our 3-D physical models of natural and normal amitosis (cytokinesis), for prokaryotes (bacterial cells) in M phase. We propose following hypotheses: Chromosome rings exclusion: No normally and naturally replicated chromosome rings (RCR) can occupy the same prokaryote, a bacterial cell. The RCR produce spontaneous and strong electromagnetic fields (EMF), that can be alternated environmentally, in protoplasm and cortex. The EMF is approximately a repulsive quasi-static electric (slowly variant and mostly electric) field (EF). The EF forces between the RCR are strong enough, and orderly accumulate contractile proteins that divide the procaryotes in the cell cortex of division plane or directly split the cell compartment envelope longitudinally. The radial component of the EF forces could also make furrows or cleavages of procaryotes. The EF distribution controls the protoplasm partition and completes the amitosis (cytokinesis). After the cytokinesis, the spontaneous and strong EF disappear because the net charge accumulation becomes weak, in the protoplasm. The exclusion is because the two sets of informative objects (RCR) have identical DNA codes information and they are electro magnetically identical, therefore they repulse from each other. We also compare divisions among eukaryotes, prokaryotes, mitochondria and chloroplasts and propose our hypothesis: The principles of our models are applied to divisions of mitochondria and chloroplasts of eucaryotes too because these division mechanisms are closer than others in a view of physics. Though we develop our model using 1 division plane (i.e., 1 cell is divided into 2 cells) as an example, the principle of our model is applied to the cases with multiple division planes (i.e., 1 cell is divided into multiple cells) too.

  16. Propulsion Physics Using the Chameleon Density Model

    NASA Technical Reports Server (NTRS)

    Robertson, Glen A.

    2011-01-01

    To grow as a space faring race, future spaceflight systems will require a new theory of propulsion. Specifically one that does not require mass ejection without limiting the high thrust necessary to accelerate within or beyond our solar system and return within a normal work period or lifetime. The Chameleon Density Model (CDM) is one such model that could provide new paths in propulsion toward this end. The CDM is based on Chameleon Cosmology a dark matter theory; introduced by Khrouy and Weltman in 2004. Chameleon as it is hidden within known physics, where the Chameleon field represents a scalar field within and about an object; even in the vacuum. The CDM relates to density changes in the Chameleon field, where the density changes are related to matter accelerations within and about an object. These density changes in turn change how an object couples to its environment. Whereby, thrust is achieved by causing a differential in the environmental coupling about an object. As a demonstration to show that the CDM fits within known propulsion physics, this paper uses the model to estimate the thrust from a solid rocket motor. Under the CDM, a solid rocket constitutes a two body system, i.e., the changing density of the rocket and the changing density in the nozzle arising from the accelerated mass. Whereby, the interactions between these systems cause a differential coupling to the local gravity environment of the earth. It is shown that the resulting differential in coupling produces a calculated value for the thrust near equivalent to the conventional thrust model used in Sutton and Ross, Rocket Propulsion Elements. Even though imbedded in the equations are the Universe energy scale factor, the reduced Planck mass and the Planck length, which relates the large Universe scale to the subatomic scale.

  17. Tactile Teaching: Exploring Protein Structure/Function Using Physical Models

    ERIC Educational Resources Information Center

    Herman, Tim; Morris, Jennifer; Colton, Shannon; Batiza, Ann; Patrick, Michael; Franzen, Margaret; Goodsell, David S.

    2006-01-01

    The technology now exists to construct physical models of proteins based on atomic coordinates of solved structures. We review here our recent experiences in using physical models to teach concepts of protein structure and function at both the high school and the undergraduate levels. At the high school level, physical models are used in a…

  18. Tactile Teaching: Exploring Protein Structure/Function Using Physical Models

    ERIC Educational Resources Information Center

    Herman, Tim; Morris, Jennifer; Colton, Shannon; Batiza, Ann; Patrick, Michael; Franzen, Margaret; Goodsell, David S.

    2006-01-01

    The technology now exists to construct physical models of proteins based on atomic coordinates of solved structures. We review here our recent experiences in using physical models to teach concepts of protein structure and function at both the high school and the undergraduate levels. At the high school level, physical models are used in a…

  19. Computer Integrated Manufacturing: Physical Modelling Systems Design. A Personal View.

    ERIC Educational Resources Information Center

    Baker, Richard

    A computer-integrated manufacturing (CIM) Physical Modeling Systems Design project was undertaken in a time of rapid change in the industrial, business, technological, training, and educational areas in Australia. A specification of a manufacturing physical modeling system was drawn up. Physical modeling provides a flexibility and configurability…

  20. A Physical Model for Gravitation and Inertia

    NASA Astrophysics Data System (ADS)

    Rasor, Ned

    2011-11-01

    A physical/analytical model of gravitation and inertia is described. The model is based on proportional expansion of the universe and its contents, along with special relativistic time delay within nucleons. An expression of the gravitational constant G is derived from the model in terms of fundamental constants and properties without adjustable parameters, [ G=he^2c^2 1pt 1ptτu(mpme)^3/2=6.67x10-8cm^3g.s^2 ] where h = Planck constant, e = electronic charge, c = speed of light, mp and me are the nucleonic and electronic masses, and τu= age of the universe. The value τu = 13.6 Gy that corresponds with the accepted value of G shown is within the uncertainty of the empirical value ofτu currently estimated from cosmic ray background and other astronomical data. A modified Newtonian dynamics and other relationships derived from the model are consistent quantitatively and functionally with a variety of observed astronomical data, some of which have been considered previously to be anomalous or based on dark matter.

  1. Fuzzy modelling of Atlantic salmon physical habitat

    NASA Astrophysics Data System (ADS)

    St-Hilaire, André; Mocq, Julien; Cunjak, Richard

    2015-04-01

    Fish habitat models typically attempt to quantify the amount of available river habitat for a given fish species for various flow and hydraulic conditions. To achieve this, information on the preferred range of values of key physical habitat variables (e.g. water level, velocity, substrate diameter) for the targeted fishs pecies need to be modelled. In this context, we developed several habitat suitability indices sets for three Atlantic salmon life stages (young-of-the-year (YOY), parr, spawning adults) with the help of fuzzy logic modeling. Using the knowledge of twenty-seven experts, from both sides of the Atlantic Ocean, we defined fuzzy sets of four variables (depth, substrate size, velocity and Habitat Suitability Index, or HSI) and associated fuzzy rules. When applied to the Romaine River (Canada), median curves of standardized Weighted Usable Area (WUA) were calculated and a confidence interval was obtained by bootstrap resampling. Despite the large range of WUA covered by the expert WUA curves, confidence intervals were relatively narrow: an average width of 0.095 (on a scale of 0 to 1) for spawning habitat, 0.155 for parr rearing habitat and 0.160 for YOY rearing habitat. When considering an environmental flow value corresponding to 90% of the maximum reached by WUA curve, results seem acceptable for the Romaine River. Generally, this proposed fuzzy logic method seems suitable to model habitat availability for the three life stages, while also providing an estimate of uncertainty in salmon preferences.

  2. Impact of detector simulation in particle physics collider experiments

    NASA Astrophysics Data System (ADS)

    Daniel Elvira, V.

    2017-06-01

    Through the last three decades, accurate simulation of the interactions of particles with matter and modeling of detector geometries has proven to be of critical importance to the success of the international high-energy physics (HEP) experimental programs. For example, the detailed detector modeling and accurate physics of the Geant4-based simulation software of the CMS and ATLAS particle physics experiments at the European Center of Nuclear Research (CERN) Large Hadron Collider (LHC) was a determinant factor for these collaborations to deliver physics results of outstanding quality faster than any hadron collider experiment ever before. This review article highlights the impact of detector simulation on particle physics collider experiments. It presents numerous examples of the use of simulation, from detector design and optimization, through software and computing development and testing, to cases where the use of simulation samples made a difference in the precision of the physics results and publication turnaround, from data-taking to submission. It also presents estimates of the cost and economic impact of simulation in the CMS experiment. Future experiments will collect orders of magnitude more data with increasingly complex detectors, taxing heavily the performance of simulation and reconstruction software. Consequently, exploring solutions to speed up simulation and reconstruction software to satisfy the growing demand of computing resources in a time of flat budgets is a matter that deserves immediate attention. The article ends with a short discussion on the potential solutions that are being considered, based on leveraging core count growth in multicore machines, using new generation coprocessors, and re-engineering HEP code for concurrency and parallel computing.

  3. Impact of detector simulation in particle physics collider experiments

    DOE PAGES

    Elvira, V. Daniel

    2017-06-01

    Through the last three decades, precise simulation of the interactions of particles with matter and modeling of detector geometries has proven to be of critical importance to the success of the international high-energy physics experimental programs. For example, the detailed detector modeling and accurate physics of the Geant4-based simulation software of the CMS and ATLAS particle physics experiments at the European Center of Nuclear Research (CERN) Large Hadron Collider (LHC) was a determinant factor for these collaborations to deliver physics results of outstanding quality faster than any hadron collider experiment ever before. This review article highlights the impact of detectormore » simulation on particle physics collider experiments. It presents numerous examples of the use of simulation, from detector design and optimization, through software and computing development and testing, to cases where the use of simulation samples made a difference in the accuracy of the physics results and publication turnaround, from data-taking to submission. It also presents the economic impact and cost of simulation in the CMS experiment. Future experiments will collect orders of magnitude more data, taxing heavily the performance of simulation and reconstruction software for increasingly complex detectors. Consequently, it becomes urgent to find solutions to speed up simulation software in order to cope with the increased demand in a time of flat budgets. The study ends with a short discussion on the potential solutions that are being explored, by leveraging core count growth in multicore machines, using new generation coprocessors, and re-engineering of HEP code for concurrency and parallel computing.« less

  4. Compass models: Theory and physical motivations

    NASA Astrophysics Data System (ADS)

    Nussinov, Zohar; van den Brink, Jeroen

    2015-01-01

    Compass models are theories of matter in which the couplings between the internal spin (or other relevant field) components are inherently spatially (typica