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Doctoral Thesis
DOI
10.11606/T.43.2016.tde-30112016-095354
Document
Author
Full name
Juan Alejandro García Alvarez
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2016
Supervisor
Committee
Maidana, Nora Lia (President)
Dias, Johnny Ferraz
Rizzutto, Marcia de Almeida
Roma, Josep Sempau
Tabacniks, Manfredo Harri
Title in Portuguese
Seções de choque de bremsstrahlung de elétrons, estudo experimental no Acelerador Microtron de São Paulo
Keywords in Portuguese
Acelerador de partículas
Elétrons
Espectroscopia
Física experimental
Seção de Choque
Abstract in Portuguese
Foram determinadas de maneira absoluta seções de choque duplamente diferenciais de produção de bremsstrahlung, para elétrons com energia cinética de 20, 50, 75 e 100~keV, nos elementos C, Al, Ag, Te, Ta e Au, e nos ângulos de emissão dos fótons $35^{\mathrm}$, $90^{\mathrm}$ e $131^{\mathrm}$. As medidas foram realizadas na linha de feixe de baixa energia do Acelerador Microtron, do Instituto de Física da Universidade de São Paulo, em um arranjo que contou com três detetores de Ge hiperpuro, dois planares e um coaxial. Os alvos finos foram confeccionados pela técnica de deposição física de vapores, enquanto suas espessuras foram caracterizadas a partir da espectrometria de retroespalhamento de Rutherford. Foi desenvolvido um modelo analítico para descrever a função reposta de detetores de Ge, que permitiu a deconvolução dos espectros de bremsstrahlung entre os 12~keV e o ponto de máxima transferência de energia, com uma resolução de 1~keV. As seções de choque obtidas apresentam uma incerteza relativa entre 3\% e 5\%, e foram comparadas com os cálculos teóricos que constituem o estado da arte na temática, e com os poucos dados experimentais encontrados na literatura.
Title in English
Electron bremsstrahlung cross sections, experimental study in the Sãao Paulo Microtron Accelerator
Keywords in English
Cross Section
Electrons
Experimental Physics
Particle accelerator
Spectrometry
Abstract in English
Bremsstrahlung doubly dierential cross sections were absolutely determined for electrons with kinetic energies of 20, 50, 75 and 100 keV, in the elements C, Al, Ag, Te, Ta e Au, and the photon emission angles of 35o, 90o and 131o. The measurements were performed at the low energy beam line of the S~ao Paulo Microtron Accelerator, using three high purity Ge detectors: two planar and one coaxial. Thin targets were obtained by the Physical Vapor Deposition technique, and their thicknesses were characterized through Rutherford Backscattering Spectroscopy. An analytical model was developed to describe the response function of Ge detectors, which allowed to unfold the bremsstrahlung spectra between 12 keV and the maximum energy transfer point, with an energetic resolution of 1 keV. The obtained cross sections present relative uncertainties between 3% and 5%. These results were compared with the higher accurate theoretical calculations and also with the experimental reports found in literature.
 
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Publishing Date
2016-11-30
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • C. Correa-Alfonso, et al. Measurement of inelastic scattering differential cross-section of 59 keV photons in 6< A<79 materials. In XXXV Reunião de Trabalho sobre Física Nuclear no Brasil, Maresias, 2012. XXXV Reunião de Trabalho sobre Física Nuclear no Brasil - Programa e Resumos., 2012. Resumo.
  • LO'PEZ-PINO, N., et al. Monte Carlo semi-empirical model for Si(Li) x-ray detector: Differences between nominal and fitted parameters [doi:10.1063/1.4804104]. In XXXV BRAZILIAN WORKSHOP ON NUCLEAR PHYSICS, Sao Sebastiao. , 2013.
  • N. Lopez-Pino, et al. Monte Carlo Model for Si(Li) detector: nominal and diferences between fitted parameters. In XXXV Reunião de Trabalho sobre Física Nuclear no Brasil, Maresias, 2012. XXXV Reunião de Trabalho sobre Física Nuclear no Brasil - Programa e Resumos., 2012. Resumo.
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