Examinando por Autor "Munévar Espitia, Edwin [0000-0002-0578-7717]"
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Ítem Diseño preliminar de un prototipo de un acelerador de iones ligeros para BNCT.Diaz Gómez, Víctor Alfonso; Munévar Espitia, Edwin; Leyva Rojas, José Alfonso; Munévar Espitia, Edwin; Munévar Espitia, Edwin [0000-0002-0578-7717]Currently, the use of medium- and low-energy particle accelerators has been extended to basic research laboratories in materials science, biomedical sciences, among others, and in terms of applications the main ones are in the generation of particle beams for imaging and therapy in different areas of medicine; in the industry they are in the characterization and optimization of materials. In this work, the physical foundations of linear accelerators have been studied, in particular different geometries and configurations of the electrodes for the acceleration system. A specific design was chosen in terms of configuration and geometry of electrodes, for its optimization through computational modeling of the acceleration system. Finally, a preliminary design for a compact linear acceleration column is obtained. Through a combination of experimental data taking and computational modeling, with the help of MATLAB-type calculation platforms, we study the equipotential lines, electric field vectors, and field lines to establish the different trajectories to be followed by deuterium ions, for the particular acceleration lines, given the different configurations and geometries of the electrodes that make up the accelerator column. To model the flow and acceleration of deuterium ions in an accelerating column. The purpose of this work is to determine whether the plasma meniscus and the beam interface can be properly modeled with MATLAB R2020a and thus, successfully predict the deuteron trajectory and beam shape over a wide range. Using MATLAB R2020a and based on experimental measurements of the electrostatic potential for a specific configuration and geometry of the accelerator column electrodes, a matrix of 6000 data characterized in electrostatic potential in 2d, i.e., V = V (x, y) was measured, which was taken as a basis to solve for the electric field: E = −∇V, using a central difference algorithm that allows one to find point by point each component of the electric field (Ex, Ey). Based on the above, we characterized the accelerating column in terms of the equipotential lines and the E field vector in the three acceleration zones, the trajectory of the particles (deuterons) accelerated in the extraction zone, the deuteron motion in the saturation zone, the kinetic energy of the ionized deuterium beam, and a 3D design based on the different columns studied. From the results obtained in this investigation, it is verified that the selected column and its electrode configuration fulfills the conditions to be used in medical application of BNCT. The column is characterized and the blueprint and three-dimensional designs are finally obtained, describing each of its parts and materials for its future construction.Ítem Evaluación computacional de la contribución de la captura neutrónica por 14N a la dosis absorbida en una muestra de tejido enriquecido con 10BHuertas Avendaño, Hollman Alexander; Munévar Espitia, Edwin; Munévar Espitia, Edwin [0000-0002-0578-7717]Tissue is primarily made up of elements such as hydrogen, carbon, oxygen, and nitrogen. Among them, nitrogen has the largest neutron capture cross section. In a nitrogen neutron capture reaction (NNCR), an energetic proton is emitted that rapidly loses its energy along its path, and a high probability is expected that this released energy will be deposited within the tissue in question. Therefore, even if the percentage of nitrogen (by mass) is on the order of 3% in a typical tissue, its effect is significant and cannot be ignored. In this work, the 14N neutron capture reaction is simulated using the GEANT4 toolkit in order to characterize the reaction in terms of kinematic quantities, deposited energies, and secondary particle dose contribution. Finally, it was found that the absorbed dose associated with the secondary protons of the neutron capture reaction by nitrogen is between the values of 3.1×−14 Gy and 4.7×−14 Gy for energy values of the incident neutron beam between 0.025 and 1.000. eV, respectively. These values establish that the corresponding percentage value is about 17% of the total tissue-associated dose and the absorbed dose associated with secondary 14C atoms from the nitrogen neutron capture reaction is between 2.2×−15 and 3.4× −15 Gy for incident beam energies between 0.025 and 1.000 eV, respectively. These values establish that the corresponding percentage value is close to 1% of the total tissue-associated dose.Ítem Prospección de isla de calor urbana mediante firmas espectrales de calor en la ciudad de Bogotá D.C. en el periodo 1985-2022Ávila Sabogal, Edwin Alejandro; Martínez Pinilla Jhonathan Fabián; Munévar Espitia, Edwin; Munévar Espitia, Edwin [0000-0002-0578-7717]The urban heat island phenomenon has been studied in large cities of the world because it affects the climate, generating an increase in the effects of climate change, due to the increase of the urban area by anthropogenic processes in recent decades. This study was developed over the territory of Bogota, and its objective was to carry out a thermal prospection with spectral heat signatures between 1985 and 2022. For the analysis, Landsat satellite images provided by the U.S. Geological Survey were taken; they were processed by remote sensing techniques in two geographic information systems to compare the results obtained. It was possible to conclude that the spatiotemporal variation of urban heat islands in Bogota has increased steadily in different parts of the city during the time analyzed.