Thesis (M.S.)--East Carolina University, 2009. / Presented to the faculty of the Department of Physics. Advisor: Michael Dingfelder. Title from PDF t.p. (viewed Apr. 23, 2010). Includes bibliographical references.

Thesis--Ph. D., University of Hong Kong, 1983.

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

Thesis--University of California, Berkeley, 1960. / "Physics and Mathematics" -t.p. "TID-4500 (15th Ed.)" -t.p. Includes bibliographical references (p. 50-51).

Thesis--University of California, Berkeley, 1963. / "UC-34 Physics" -t.p. "TID-4500 (19th Ed.)" -t.p. Includes bibliographical references (p. 68-69).

Thesis--University of California, Berkeley, 1959. / "Physics and Mathematics" -t.p. Includes bibliographical references (p. 50-51).

Thesis (Ph.D.)--University of California, Berkeley, 1959. / "Physics and Mathematics"-t.p. Includes bibliographical references (p. 59-60).

Thesis (M.S. in Physics)--United States Naval Postgraduate School, 1959. / "Physics and Mathematics" -t.p. Includes bibliographical references (p. 22).

Orientadores: Marco Aurelio Pinheiro Lima, Marcio Henrique Franco Bettega / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-09T02:36:32Z (GMT). No. of bitstreams: 1 Lopes_AdrianadoRocio_D.pdf: 1199450 bytes, checksum: 35d2c55fd54d591ec1c7417e228b3cf2 (MD5) Previous issue date: 2007 / Resumo: O objetivo principal desse trabalho foi a inclusão dos efeitos de polarização nos cálculos de seção de choque de espalhamento utilizando potenciais modelo. A implementação foi feita no método multicanal de Schwinger com pseudopotencial, utilizando uma descrição do potencial de polarização através de uma combinação de funções gaussianas. Com esse potencial, visamos diminuir o custo computacional existente na inclusão do efeito de polarização em um cálculo ab-initio. Utilizamos três potenciais conhecidos na literatura, sendo o primeiro o potencial que relaciona um efeito de curto alcance (correlação), derivado de um modelo de gás de elétrons livres, com o longo alcance (polarização). O segundo potencial possui a forma mais simples, constante para raios perto da origem, e decai como um potencial de polarização. O terceiro potencial possui um fator exponencial que faz o seu valor ser próximo de zero na origem e decai como um potencial de polarização. Apresentamos um modelo de polarização descrito pelo deslocamento da densidade de carga com um parâmetro calculado de forma ab-initio. Utilizando o terceiro potencial modelo calculamos a seção de choque integral, de transferência de momento e diferencial para as moléculas de CH4, SiH4, GeH4, PbH4, SnH4, CF4 e SiF4. Os resultados obtidos foram comparados com os dados existentes na literatura e obtivemos uma boa concordância entre eles / Abstract: The aim of this work is the inclusion of polarization effects in the calculations of scattering cross section by using model potentials. The implementation was made in the Schwinger multichannel method with pseudopotentials, using a description of polarization potential with gaussians functions. With this potential we entend to reduce the computational cost present in the inclusion of polarization effects through ab-initio calculation. We use three potentials that can be found in the literature. The first potential relates the short range effect (correlation) derivated from a free electron gas model, with the long range effect (polarization). The second potential has the simplest form, for radius close to zero the potential tends to a constant, and for large r it decays like a polarization potential. The third potential has a exponential factor that is zero in the origin and it decays like a polarization potential for large r. We present a polarization model described by a displacement of a eletric charge density with a ab-initio calculated parameter. Using the third model potential we calculated the integral, momentum transfer and diferential cross section for CH4, SiH4, GeH4, PbH4, SnH4, CF4and Si F4molecules. Our results had been compared with experimental data and we have good agreement / Doutorado / Física Atômica e Molecular / Doutor em Ciências

L-shell x-ray production cross sections are presented for Fe, Ni, Cu, Zn, Ga, and Ge by 0.5- to 5.0-MeV protons and by 0.5- to 8.0-MeV helium ions and Ca, Fe, Ni, Cu, and Ge by 0.75- to 4.5-MeV lithium ions. These measurements are compared to the first Born theory and the perturbed-stationary- state theory with energy-loss, Coulomb deflection, and relativistic corrections (ECPSSR). The results are also compared to previous experimental investigations. The high precision x-ray measurements were performed with a windowless Si(Li) detector. The efficiency of the detector was determined by the use of thin target atomic-field bremsstrahlung produced by 66.5 keV electrons. The measured bremsstrahlung spectra were compared to theoretical bremsstrahlung distributions in order to obtain an efficiency versus energy curve. The targets for the measurement were manufactured by the vacuum evaporation of the target element onto thin foils of carbon. Impurities in the carbon caused interferences inthe L-shell x-ray peaks. Special cleansing procedures were developed that reduced the impurity concentrations in the carbon foil, making the use of less than 5 μg/cm^2 targets possible. The first Born theory is seen to greatly overpredict the data at low ion energies. The ECPSSR theory matches the data very well at the high energy region. At low energies, while fitting the data much more closely than the first Born theory, the ECPSSR theory does not accurately predict the trend of the data. This is probably due to the onset of molecular-orbital effects, a mechanism not accounted for in the ECPSSR theory.