Re-engineering a nanodosimetry Monte Carlo code into Geant4: software design and first results

A set of physics models for nanodosimetry simulation is being re-engineered for use in Geant4-based simulations. This extension of Geant4 capabilities is part of a larger scale R&D project for multi-scale simulation involving adaptable, co-working condensed and discrete transport schemes. The project in progress reengineers the physics modeling capabilities associated with an existing FORTRAN track-structure code for nanodosimetry into a software design suitable to collaborate with an object oriented simulation kernel. The first experience and results of the ongoing re-engineering process are presented.Comment: 4 pages, 2 figures and images, to appear in proceedings of the Nuclear Science Symposium and Medical Imaging Conference 2009, Orland

Secondary ionisations in a wall-less ion-counting nanodosimeter: quantitative analysis and the effect on the comparison of measured and simulated track structure parameters in nanometric volumes

The object of investigation in nanodosimetry is the physical characteristics of the microscopic structure of ionising particle tracks, i.e. the sequence of the interaction types and interaction sites of a primary particle and all its secondaries, which reflects the stochastic nature of the radiation interaction. In view of the upcoming radiation therapy with protons and carbon ions, the ionisation structure of the ion track is of particular interest. Owing to limitations in current detector technology, the only way to determine the ionisation cluster size distribution in a DNA segment is to simulate the particle track structure in condensed matter. This is done using dedicated computer programs based on Monte Carlo procedures simulating the interaction of the primary ions with the target. Hence, there is a need to benchmark these computer codes using suitable experimental data. Ionisation cluster size distributions produced in the nanodosimeter\u27s sensitive volume by monoenergetic protons and alpha particles (with energies between 0.1 MeV and 20 MeV) were measured at the PTB ion accelerator facilities. C3H8 and N2 were alternately used as the working gas. The measured data were compared with the simulation results obtained with the PTB Monte-Carlo code PTra [B. Grosswendt, Radiat. Environ. Biophys. 41, 103 (2002); M.U. Bug, E. Gargioni, H. Nettelbeck, W.Y. Baek, G. Hilgers, A.B. Rosenfeld, H. Rabus, Phys. Rev. E 88, 043308 (2013)]. Measured and simulated characteristics of the particle track structure are generally in good agreement for protons over the entire energy range investigated. For alpha particles with energies higher than the Bragg peak energy, a good agreement can also be seen, whereas for energies lower than the Bragg peak energy differences of as much as 25% occur. Significant deviations are only observed for large ionisation cluster sizes. These deviations can be explained by a background consisting of secondary ions. These ions are produced in the region downstream of the extraction aperture by electrons with a kinetic energy of about 2.5 keV, which are themselves released by ions of the primary ionisation cluster hitting an electrode in the ion transport system. Including this background of secondary ions in the simulated cluster size distributions leads to a significantly better agreement between measured and simulated data, especially for large ionisation clusters. Graphical abstract: [Figure not available: see fulltext.

Secondary ionisations in a wall-less ion-counting nanodosimeter: quantitative analysis and the effect on the comparison of measured and simulated track structure parameters in nanometric volumes

The object of investigation in nanodosimetry is the physical characteristics of the microscopic structure of ionising particle tracks, i.e. the sequence of the interaction types and interaction sites of a primary particle and all its secondaries, which reflects the stochastic nature of the radiation interaction. In view of the upcoming radiation therapy with protons and carbon ions, the ionisation structure of the ion track is of particular interest. Owing to limitations in current detector technology, the only way to determine the ionisation cluster size distribution in a DNA segment is to simulate the particle track structure in condensed matter. This is done using dedicated computer programs based on Monte Carlo procedures simulating the interaction of the primary ions with the target. Hence, there is a need to benchmark these computer codes using suitable experimental data. Ionisation cluster size distributions produced in the nanodosimeter\u27s sensitive volume by monoenergetic protons and alpha particles (with energies between 0.1 MeV and 20 MeV) were measured at the PTB ion accelerator facilities. C3H8 and N2 were alternately used as the working gas. The measured data were compared with the simulation results obtained with the PTB Monte-Carlo code PTra [B. Grosswendt, Radiat. Environ. Biophys. 41, 103 (2002); M.U. Bug, E. Gargioni, H. Nettelbeck, W.Y. Baek, G. Hilgers, A.B. Rosenfeld, H. Rabus, Phys. Rev. E 88, 043308 (2013)]. Measured and simulated characteristics of the particle track structure are generally in good agreement for protons over the entire energy range investigated. For alpha particles with energies higher than the Bragg peak energy, a good agreement can also be seen, whereas for energies lower than the Bragg peak energy differences of as much as 25% occur. Significant deviations are only observed for large ionisation cluster sizes. These deviations can be explained by a background consisting of secondary ions. These ions are produced in the region downstream of the extraction aperture by electrons with a kinetic energy of about 2.5 keV, which are themselves released by ions of the primary ionisation cluster hitting an electrode in the ion transport system. Including this background of secondary ions in the simulated cluster size distributions leads to a significantly better agreement between measured and simulated data, especially for large ionisation clusters. Graphical abstract: [Figure not available: see fulltext.

Geant4-related R&D for new particle transport methods

A R&D project has been launched in 2009 to address fundamental methods in radiation transport simulation and revisit Geant4 kernel design to cope with new experimental requirements. The project focuses on simulation at different scales in the same experimental environment: this set of problems requires new methods across the current boundaries of condensed-random-walk and discrete transport schemes. An exploration is also foreseen about exploiting and extending already existing Geant4 features to apply Monte Carlo and deterministic transport methods in the same simulation environment. An overview of this new R&D associated with Geant4 is presented, together with the first developments in progress.Comment: 4 pages, to appear in proceedings of the Nuclear Science Symposium and Medical Imaging Conference 2009, Orland

R&D on co-working transport schemes in Geant4

A research and development (R&D) project related to the extension of the Geant4 toolkit has been recently launched to address fundamental methods in radiation transport simulation. The project focuses on simulation at different scales in the same experimental environment; this problem requires new methods across the current boundaries of condensed-random-walk and discrete transport schemes. The new developments have been motivated by experimental requirements in various domains, including nanodosimetry, astronomy and detector developments for high energy physics applications.Comment: To be published in the Proceedings of the CHEP (Computing in High Energy Physics) 2009 conferenc

Design and performance evaluations of generic programming techniques in a R&D prototype of Geant4 physics

A R&D project has been recently launched to investigate Geant4 architectural design in view of addressing new experimental issues in HEP and other related physics disciplines. In the context of this project the use of generic programming techniques besides the conventional object oriented is investigated. Software design features and preliminary results from a new prototype implementation of Geant4 electromagnetic physics are illustrated. Performance evaluations are presented. Issues related to quality assurance in Geant4 physics modelling are discussed.Comment: To be published in the Proceedings of the CHEP (Computing in High Energy Physics) 2009 conferenc

Aminoetoxivinilglicina no manejo de colheita de macieiras "galaxy" sob tela antigranizo.

A macieira (Malus domestica Borkh.) é uma fruteira de clima temperado de grande importância econômica mundial, sendo ?Gala? e ?Fuji? as cultivares mais produzidas no Brasil. Em macieiras ?Gala? o período de colheita se dá em um curto período de tempo, o que demanda grande quantidade de mão de obra e resulta em queda pré-colheita de frutos e colheita de frutos sobre maduros, inviabilizando o armazenamento a longo prazo. No cultivo da macieira, a instalação de telas antigranizo é uma ferramenta importante na prevenção de danos causados por tempestades de granizo, muito frequentes no Sul do Brasil (MARTINS et al., 2017). Entretanto, o uso de telas interfere no microclima do pomar, resultando em aumento no ciclo vegetativo das plantas e alterando também a produtividade e qualidade de frutos (MUPAMBI et al., 2018; INGLESIAS; ALEGRE, 2006). Neste cenário, a aplicação de aminoetoxivinilglicina (AVG) é uma alternativa para a promoção do atraso na maturação, controle de queda pré-colheita, aumento da firmeza de polpa e massa média de frutos, proporcionando maior potencial de conservação, uma vez que diminui a biossíntese de etileno (HAWERROTH et al., 2011). Tendo isso em vista, o objetivo do presente estudo foi avaliar o efeito da aplicação de AVG no manejo de colheita de macieiras ?Galaxy? sob tela antigranizo, nas condições de cultivo de Monte Alegre dos Campos-RS, no ciclo 2020/2021

Manejo da indução de brotação de macieiras "gala" na região de Vacaria, RS.

A utilização de indutores de brotação é uma prática indispensável no manejo da macieira nas condições climáticas das principais regiões produtoras do Brasil no intuito de minimizar os efeitos do insuficiente acúmulo de frio hibernal sob a capacidade produtiva dos pomares. A cianamida hidrogenada em combinação ao óleo mineral tem sido a principal estratégia para indução da brotação de gemas de macieiras dos grupos Gala e Fuji no Brasil. Além disso, tem sido obtidos resultados positivos no manejo da indução de brotação de gemas pelo uso de bioestimulantes, sobretudo em programas de aplicação sequencial de indutores de brotação. Para tanto, a realização do presente ensaio experimental teve por objetivo avaliar a eficiência de diferentes manejos para a indução de brotação de macieiras ?Gala? cv. Baigent, em Vacaria-RS, no ciclo de cultivo 2020/2021

Indução de brotação de gemas de macieiras "galaxy" manejadas sob tela antigranizo.

A indução de brotação é uma prática cultural obrigatória no manejo de macieiras ?Gala? sob condições de insuficiência em frio hibernal, características da maior parte das regiões produtoras de maçã no Brasil. A cultura da macieira quando cultivada em regiões como o Sul do Brasil tendem a ter carência de acúmulo de frio para atender suas exigências fisiológicas manifestando brotações deficientes e desuniformes (PETRI; LEITE, 2004); Segundo Petri et al. (2021), a deficiência de brotação de gemas acarreta redução de produtividade e qualidade de frutos, sendo os reflexos observados na safra atual e nos ciclos de produção posteriores. Em pomares de macieira sob tela antigranizo existe a tendência de maior crescimento vegetativo, podendo implicar em maior dificuldade para a indução de brotação de gemas. Dessa forma, a efetividade dessa prática cultural é fundamental para uniformização da brotação e florescimento de maneira a regularizar a frutificação de pomares sob tela antigranizo. Nesse sentido, o objetivo do trabalho foi avaliar a eficiência de diferentes manejos para a indução de brotação de macieiras ?Gala? sob tela antigranizo, no ciclo de cultivo produtivo 2021/2022

Formação de rebrotes em diferentes porta-enxertos em macieiras 'gala' manejadas em sistema de condução bidimensional.

O Brasil é o décimo segundo maior produtor mundial de maçãs (FAOSTAT, 2021), com a cadeia da macieira apresentando-se como uma das mais organizadas do setor agrícola do país, sendo exemplo de união entre setor público e privado, o que fomenta um grande pacote tecnológico (PETRI; LEITE, 2008). Dentre os recentes resultados de pesquisa implementados nos pomares, tem-se a introdução de novos sistemas de condução, como o bidimensional, o qual busca antecipar o retorno econômico, reduzir e facilitar a necessidade tratos culturais após a formação do pomar e elevar a qualidade dos frutos e a produtividade do pomar