2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD), 2016
We report preliminary results of an extensive investigation of theoretical and semi-empirical cal... more We report preliminary results of an extensive investigation of theoretical and semi-empirical calculations of electron impact ionization cross sections, detailed by individual shells: they encompass the well known tabulations of the EEDL data library (also distributed within ENDF/B-VII) used by Geant4, MCNP and other codes, recent calculations used in Penelope, as well as other models not yet used in general-purpose Monte Carlo transport codes. All models have been subject to a rigorous validation test against a wide collection of experimental measurements. Special attention has been devoted to possible sources of systematics affecting the validation process, both of physical and mathematical origin. As most of the data reported in the literature as experimental measurements of ionization cross sections actually derive from X-ray production measurements, the systematic effect of different compilations of fluorescence yields has been quantitatively assessed. The compatibility of calculated and experimental cross sections has been further examined with categorical analysis methods to determine whether the observed differences across the various models are statistically significant. The results of this validation process identify objectively and quantitatively the state of the art in modeling electron impact ionization; they are relevant for the improvement of ionization modeling in Monte Carlo codes.
In geology field, the experimental or computational simulation of the sediment deposition process... more In geology field, the experimental or computational simulation of the sediment deposition process is widely used to characterize regions and possible findings. Noninvasive methods are the best way to evaluate sediments; in order of not to destroy the information of the sediment deposition structure. The use of computed tomography (CT) techniques to get images of sediments will be evaluated. A CT will be analyzed has a two stage process, the scan of body test to produce a set of X-ray images and the reconstruction step where the set of X-ray images is processed by computational algorithm to generate cross-sectional images of the scanned object. To test the method the X-ray images are generated using the Monte Carlo method with a XRMC tool, and the simulated images are 3D reconstructed using the Feldkamp, David e Kress algorithm. The reconstruction planes and the volume generated in the simulation showed very similar after a visual comparison for all of tested volumes. However a stati...
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2017
New cross section calculations are usually advertised as improvements over previous ones. Neverth... more New cross section calculations are usually advertised as improvements over previous ones. Nevertheless these claims are not always supported by rigorous statistical tests. A set of electron impact ionization cross sections for inner shells, suitable for Monte Carlo particle transport, has been evaluated in a large scale validation test with respect to an extensive collection of experimental data retrieved from the literature. It includes the cross sections tabulated in EEDL (Evaluated Electron Data Library), recent calculations by Bote and Salvat, the BinaryEncounter-Bethe (BEB) model and the Deutsch-Mrk (DM) model. The cross sections were compared to experimental data by means of goodness-of-fit tests. The picture that emerges from the validation test does not fully support the expectations of improvement. The complete and final results of the validation process are reported in detail and critically discussed.
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2017
In this paper are presenting a comparison by using experimental data about chemical damage for al... more In this paper are presenting a comparison by using experimental data about chemical damage for all possible physics list for Geant4-DNA (Geant4 version 10.02.p01) for protons incident beam interacting with homogeneous nano-layers of water. Associated to the chemical damage it were evaluated: radial profile of energy deposition, profile of energy deposition on depth, number of interactions, proportion among possible processes and stopping power of the incident particle. The application considers water ultra-thin layers of thicknesses from 2 nm to 200 nm with monodirectional and monochromatic (2 MeV to 20 MeV) protons impinging normally on its entrance surface. It was evoked the standard physics list (“G4EmDNAPhysics” class) and other 5 physics list available (names Opt 1 up to 5). Concerning the experimental data, the films were bombarded by 2 MeV H+ textbf in vacuum at a HVEE 3 MV Tandetron and Xray photoelectron spectroscopy was performed on the irradiated samples at Université de ...
RESUMO Para garantir a proteção dos indivíduos, diversos materiais são utilizados para blindagem ... more RESUMO Para garantir a proteção dos indivíduos, diversos materiais são utilizados para blindagem de radiação ionizante, dentre eles o sulfato de bário (barita), que se destaca por apresentar boa atenuação de feixes de fótons em diferentes energias, incluindo aqueles utilizados em radioterapia. Nesse contexto, este trabalho propõe três traços de concretos baritados: T.REF (referência), T.10%SA (com substituição de 10% de cimento Portland por sílica ativa) e T.10%CV (com substituição de 10% de cimento Portland por cinza volante) para investigar os efeitos da blindagem da radiação ionizante gerada por um equipamento de radioterapia. As amostras de concreto foram caracterizadas em relação as suas densidades aparentes e resistência à compressão axial. Para avaliar eficácia da blindagem, foram realizadas medidas de atenuação da radiação do feixe primário gerado por um acelerador linear, para tensões máximas de aceleração de 6 MV e 10 MV, em função da espessura dos corpos de prova. Quanto ...
2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC), 2018
Evaluated data libraries for electron-photon transport are most important components in Monte Car... more Evaluated data libraries for electron-photon transport are most important components in Monte Carlo simulation and have been used in general-purpose Monte Carlo codes for decades. A new version of evaluated atomic data libraries, called EPICS2017, was released in early 2018. This paper reports an extensive assessment of EPICS2017, focused on what has changed, and evaluates the impact of using the new libraries in a Monte Carlo simulation environment. The results provide guidelines for developers and users of Monte Carlo codes wishing to use the new libraries. In addition, they also highlight opportunities for improving the data libraries in future releases.
This is the introductory manuscript for the Special Issue on Fighting Against COVID-19. In this, ... more This is the introductory manuscript for the Special Issue on Fighting Against COVID-19. In this, the guest editors commenters all the accepted manuscripts for publication, presenting them grouped on four main subtopics: (I) COVID-19 dissemination modeling; (II) follow up of social isolation; (III) artificial intelligence and deep learning applied to COVID-19 diagnosis; and (IV) different technological developments on fighting COVID-19.
2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD), 2016
We report preliminary results of an extensive investigation of theoretical and semi-empirical cal... more We report preliminary results of an extensive investigation of theoretical and semi-empirical calculations of electron impact ionization cross sections, detailed by individual shells: they encompass the well known tabulations of the EEDL data library (also distributed within ENDF/B-VII) used by Geant4, MCNP and other codes, recent calculations used in Penelope, as well as other models not yet used in general-purpose Monte Carlo transport codes. All models have been subject to a rigorous validation test against a wide collection of experimental measurements. Special attention has been devoted to possible sources of systematics affecting the validation process, both of physical and mathematical origin. As most of the data reported in the literature as experimental measurements of ionization cross sections actually derive from X-ray production measurements, the systematic effect of different compilations of fluorescence yields has been quantitatively assessed. The compatibility of calculated and experimental cross sections has been further examined with categorical analysis methods to determine whether the observed differences across the various models are statistically significant. The results of this validation process identify objectively and quantitatively the state of the art in modeling electron impact ionization; they are relevant for the improvement of ionization modeling in Monte Carlo codes.
In geology field, the experimental or computational simulation of the sediment deposition process... more In geology field, the experimental or computational simulation of the sediment deposition process is widely used to characterize regions and possible findings. Noninvasive methods are the best way to evaluate sediments; in order of not to destroy the information of the sediment deposition structure. The use of computed tomography (CT) techniques to get images of sediments will be evaluated. A CT will be analyzed has a two stage process, the scan of body test to produce a set of X-ray images and the reconstruction step where the set of X-ray images is processed by computational algorithm to generate cross-sectional images of the scanned object. To test the method the X-ray images are generated using the Monte Carlo method with a XRMC tool, and the simulated images are 3D reconstructed using the Feldkamp, David e Kress algorithm. The reconstruction planes and the volume generated in the simulation showed very similar after a visual comparison for all of tested volumes. However a stati...
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2017
New cross section calculations are usually advertised as improvements over previous ones. Neverth... more New cross section calculations are usually advertised as improvements over previous ones. Nevertheless these claims are not always supported by rigorous statistical tests. A set of electron impact ionization cross sections for inner shells, suitable for Monte Carlo particle transport, has been evaluated in a large scale validation test with respect to an extensive collection of experimental data retrieved from the literature. It includes the cross sections tabulated in EEDL (Evaluated Electron Data Library), recent calculations by Bote and Salvat, the BinaryEncounter-Bethe (BEB) model and the Deutsch-Mrk (DM) model. The cross sections were compared to experimental data by means of goodness-of-fit tests. The picture that emerges from the validation test does not fully support the expectations of improvement. The complete and final results of the validation process are reported in detail and critically discussed.
2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 2017
In this paper are presenting a comparison by using experimental data about chemical damage for al... more In this paper are presenting a comparison by using experimental data about chemical damage for all possible physics list for Geant4-DNA (Geant4 version 10.02.p01) for protons incident beam interacting with homogeneous nano-layers of water. Associated to the chemical damage it were evaluated: radial profile of energy deposition, profile of energy deposition on depth, number of interactions, proportion among possible processes and stopping power of the incident particle. The application considers water ultra-thin layers of thicknesses from 2 nm to 200 nm with monodirectional and monochromatic (2 MeV to 20 MeV) protons impinging normally on its entrance surface. It was evoked the standard physics list (“G4EmDNAPhysics” class) and other 5 physics list available (names Opt 1 up to 5). Concerning the experimental data, the films were bombarded by 2 MeV H+ textbf in vacuum at a HVEE 3 MV Tandetron and Xray photoelectron spectroscopy was performed on the irradiated samples at Université de ...
RESUMO Para garantir a proteção dos indivíduos, diversos materiais são utilizados para blindagem ... more RESUMO Para garantir a proteção dos indivíduos, diversos materiais são utilizados para blindagem de radiação ionizante, dentre eles o sulfato de bário (barita), que se destaca por apresentar boa atenuação de feixes de fótons em diferentes energias, incluindo aqueles utilizados em radioterapia. Nesse contexto, este trabalho propõe três traços de concretos baritados: T.REF (referência), T.10%SA (com substituição de 10% de cimento Portland por sílica ativa) e T.10%CV (com substituição de 10% de cimento Portland por cinza volante) para investigar os efeitos da blindagem da radiação ionizante gerada por um equipamento de radioterapia. As amostras de concreto foram caracterizadas em relação as suas densidades aparentes e resistência à compressão axial. Para avaliar eficácia da blindagem, foram realizadas medidas de atenuação da radiação do feixe primário gerado por um acelerador linear, para tensões máximas de aceleração de 6 MV e 10 MV, em função da espessura dos corpos de prova. Quanto ...
2018 IEEE Nuclear Science Symposium and Medical Imaging Conference Proceedings (NSS/MIC), 2018
Evaluated data libraries for electron-photon transport are most important components in Monte Car... more Evaluated data libraries for electron-photon transport are most important components in Monte Carlo simulation and have been used in general-purpose Monte Carlo codes for decades. A new version of evaluated atomic data libraries, called EPICS2017, was released in early 2018. This paper reports an extensive assessment of EPICS2017, focused on what has changed, and evaluates the impact of using the new libraries in a Monte Carlo simulation environment. The results provide guidelines for developers and users of Monte Carlo codes wishing to use the new libraries. In addition, they also highlight opportunities for improving the data libraries in future releases.
This is the introductory manuscript for the Special Issue on Fighting Against COVID-19. In this, ... more This is the introductory manuscript for the Special Issue on Fighting Against COVID-19. In this, the guest editors commenters all the accepted manuscripts for publication, presenting them grouped on four main subtopics: (I) COVID-19 dissemination modeling; (II) follow up of social isolation; (III) artificial intelligence and deep learning applied to COVID-19 diagnosis; and (IV) different technological developments on fighting COVID-19.
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Papers by Gabriela Hoff