Differential cross sections for the elastic scattering of low energy (20 MeV) positive and negative pions from ¹²C and ⁴⁰Ca have been measured. This measurement was performed at TRIUMF using the QQD low energy pion spectrometer at 11 angles between 45° and 125°. The π⁺ ¹²C data are in good agreement with [OBG⁺83], as are the π⁻ ¹²C data with [WBB+87], indicating that the overall normalization of the cross sections is good. However, the π± ⁴⁰Ca data do not agree well with the previously published data of [WMR+88]. An optical potential model, whose parameters were determined from pionic atom data, was used to predict these differential cross sections. Two sets of parameters were used in the model. One set was determined from fits to "normal" pionic atom data, while another set was extracted from fits to "anomalous" data where level shifts and widths do not compare to theoretical values obtained when the normal set of parameters is used. In all the above cases, the experimental data best fits the optical model predictions of [FG80,Fri88b] when the normal set of parameters is used. The qualitative agreement of the data to the "normal" optical model predictions indicates that the pionic anomaly effects do not extend to positive pion energy values. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

by Pang Kam Moon. / Title also in Chinese characters. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 120-121). / LIST OF FIGURES --- p.iv / ACKNOWLEDGEMENTS --- p.x / ABSTRACT --- p.xi / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter CHAPTER 2 --- SPONTANEOUS BRILLOUIN SCATTERING IN MICRODROPLETS --- p.10 / Chapter 2.1 --- Outline of the theory of Spontaneous Brillouin Scattering / Chapter 2.2 --- Low-Q Spontaneous Brillouin Scattering / Chapter 2.3 --- High-Q Spontaneous Brillouin Scattering / Chapter CHAPTER 3 --- FORMULATION AND RESULTS OF STEADY STATE SBS --- p.16 / Chapter 3.1 --- SBS in Extended and Spherical Media / Chapter 3.2 --- Formulation / Chapter 3.3 --- Monochromatic Plane Wave with Definite Helicity / Chapter 3.4 --- Lorentzian Approximation to J(z) / Chapter 3.5 --- Edge Illumination / Chapter CHAPTER 4 --- TRANSIENT EFFECTS ON INTERNAL INTENSITY --- p.56 / Chapter 4.1 --- Enhancements for Internal Intensity / Chapter 4.2 --- Formulation for Transient Incident Pulse Gaussian Profile / Chapter 4.3 --- Absorption Effects / Chapter CHAPTER 5 --- TRANSIENT STIMULATED BRILLOUIN SCATTERING --- p.74 / Chapter 5.1 --- Slowly Varying Phase and Amplitude Approximation / Chapter 5.2 --- Long Temporal Gaussian Profile Incident Light / Chapter 5.3 --- Short Temporal Gaussian Profile Incident Light / Chapter CHAPTER 6 --- SBS IN MICRODROPLETS WITH ABSORPTION --- p.82 / Chapter 6.1 --- Steady State SBS with Absorption / Chapter 6.2 --- Long Temporal Gaussian Profile Incident Light / Chapter 6.3 --- Short Temporal Gaussian Profile Incident Light / Chapter 6.4 --- Singly Resonant SBS / Chapter CHAPTER 7 --- CONCLUSION --- p.98 / APPENDIX A --- p.100 / APPENDIX B --- p.102 / APPENDIX C --- p.106 / APPENDIX D --- p.108 / REFERENCES --- p.120

Graduation date: 1995

The Mueller scattering matrix elements (S(ij)) and the cross-sections for the scattering of an electromagnetic plane wave from two infinitely long, parallel, circular cylinders at oblique incidence are derived. Each cylinder can be of arbitrary materials (any refractive index). The incident wave can be in any polarization state. To find the scattering coefficients, which are essential for calculating S(ij) and the cross-sections, the multiple scatterings were taken into account for all orders such that the 'incident' field of one cylinder is the true incident field plus the scattered field from the other cylinder. The formal solutions of the scalar wave equation are obtained in the three regions; the region outside the two cylinders, the region inside each cylinder and the scattering coefficients are found by satisfying the boundary conditions. A computer program was written. The scattering coefficients are calculated from a matrix equation. This is the first comprehensive study of the two cylinder problem. Special cases are considered in comparison with other published works. Calculations are shown of S(ij) and of cross-sections for some selected cases of configurations of the two cylinders.

A modified version of the coupled-channel computer code CHUCK has been employed to calculate theoretical angular distributions for the inelastic scattering protons by 40 Ca, 90Zr, and 208Pb. Utilizing the vibrational collective model, with optical-model parameters generated by an optimized fit to the elastic data, angular distributions of differential cross-sections for excitations from the ground state to the first 3ˉ state of 40Ca, 90Zr and 208Pb have been calculated. These calculated angular distributions, for protons incident upon 40Ca at 135 and 160 MeV, 90Zr at 135 MeV, and 208Pb at 80, 121 and 160 MeV are compared to experimental data taken at the Indiana University Cyclotron Facility. Various treatments of the spin-orbit interaction have been investigated. Results of the study clearly demonstrate a breakdown of the collective model at higher energies of the incident projectile.

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O espalhamento elástico de um sistema nuclear leve, He- SOB. 3, é analisado dentro do formalismo do Método de Coordenadas Geradoras usando o procedimento formulado por Piza e Passos (PP 78). A mesma técnica numérica é adotada para descrever os estados ligados e propriedades de espalhamento. As defasagens das ondas parciais 1=0,1,2 e 3 e as energias dos estados ligados do Be SOB. 7 são calculados utilizando interações dependentes da densidade Skyrme III e IV. Os resultados são confrontados com os dados experimentais e é proposta uma prescrição para a escolha dos parâmetros do potencial de Skyrme que melhora a descrição desse sistema. / The elastic scattering of a light nuclear system, 3He -, is analised in the framework of the Generator Coordinate Method (GCM) using the approach of Piza and Passos (PP 78). The same numerical technique is adopted to describe the bound states and scattering properties. A density dependent interaction (Skyrme III and IV) is used to calculate the phase-shifts for partial waves 1=O,1 ,2 and 3, and the bound states energies of 7Be. A new set of parameter for the Skyrme force is proposed in order to improve the agreement with experimental data.

Li Yuen Yee Laura = 激光懸浮慢速揮發微液滴之彈性散射光之研究 / 李婉兒. / Thesis submitted in: August 2005. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 97-99). / Text in English; abstracts in English and Chinese. / Li Yuen Yee Laura = Ji guang xuan fu man su hui fa wei ye di zhi tan xing san she guang zhi yan jiu / Li Waner. / Acknowledgements --- p.3 / Abstract --- p.4 / Chapter Chapter 1 --- Introduction --- p.6 / Chapter Chapter 2 --- Theory --- p.10 / Chapter 2.1 --- "Cross sections for absorption, scattering and extinction" --- p.10 / Chapter 2.2 --- Morphology-dependent resonances and spherical cavity modes assignment --- p.11 / Chapter 2.3 --- Broadening of MDR and removal of degeneracy --- p.15 / Chapter 2.4 --- Radiation pressure and stable levitation position --- p.17 / Chapter 2.4.1 --- Radiation pressure --- p.17 / Chapter 2.4.2 --- Laser levitation --- p.19 / Chapter 2.4.3 --- Stable levitation positions --- p.23 / Chapter 2.5 --- T-matrix method --- p.25 / Chapter Chapter 3 --- Experiment --- p.30 / Chapter 3.1 --- Choice of liquid --- p.30 / Chapter 3.2 --- Simultaneous recording of the differential cross-section and the position of a laser-levitated dodecane microdroplet --- p.30 / Chapter 3.3 --- Dual-wavelength experiment --- p.35 / Chapter Chapter 4 --- Data Analysis --- p.37 / Chapter 4.1 --- Upper and lower limits on the size parameter --- p.38 / Chapter 4.2 --- Refractive index --- p.40 / Chapter 4.3 --- Evaporation rate --- p.42 / Chapter 4.4 --- Acceptance angle --- p.43 / Chapter 4.5 --- Vertical position --- p.44 / Chapter Chapter 5 --- Results and Disscussions --- p.53 / Chapter 5.1 --- High-order MDR's --- p.53 / Chapter 5.2 --- Signatures of low-order resonances --- p.64 / Chapter 5.3 --- Discussions --- p.69 / Chapter Chapter 6 --- Conclusion and Future Outlook --- p.90 / Appendix 1 --- p.92 / List of Figures --- p.94 / List of Tables --- p.96 / References --- p.97

Desenvolvemos o formalismo matemático do modelo do sub-aglomerado (\"subcluster\") molecular no método do espalhamento múltiplo e aplicamo-lo no estudo da estrutura eletrônica do íon FE(CN) IND. 6 POT. 4-. Os círculos mostram que um dos principais defeitos do espalhamento múltiplo (transferência excessiva de cargas para a região interatômica) foi corrigido sensivelmente, obtendo uma distribuição de carga mais realística. O modelo do sub-aglomerado molecular dá margens a interpretações do espectro de emissão de fotoelétrons por raio X e de transições óticas desse íon, em boa concordância com os resultados experimentais. Os resultados obtidos mostram que o modelo pode ser aplicado para o estudo da estrutura eletrônica de um grande número de sistemas. / The mathematical formulation of the molecular subcluster model, within the framework of the multiple scattering method, is presented. The model is applied to the study of the electronic structure of the FE(CN) IND. 6 POT. 4- ion. The calculations show that one of the main drawback of the multiple scattering method (the unphysical charge transfer to the interatomic region) is corrected. The model leads to molecular charge distributions with a good degree of physical realism. The interpretations of the X-ray photoelectron spectrum and the optical transitions for the ion, based on the proposed model, are in good agreement with the experimental results. The calculations carried out in this work show that the molecular subcluster model can be applied to a wide range of systems.

Desenvolvemos o formalismo matemático do modelo do sub-aglomerado (\"subcluster\") molecular no método do espalhamento múltiplo e aplicamo-lo no estudo da estrutura eletrônica do íon FE(CN) IND. 6 POT. 4-. Os círculos mostram que um dos principais defeitos do espalhamento múltiplo (transferência excessiva de cargas para a região interatômica) foi corrigido sensivelmente, obtendo uma distribuição de carga mais realística. O modelo do sub-aglomerado molecular dá margens a interpretações do espectro de emissão de fotoelétrons por raio X e de transições óticas desse íon, em boa concordância com os resultados experimentais. Os resultados obtidos mostram que o modelo pode ser aplicado para o estudo da estrutura eletrônica de um grande número de sistemas. / The mathematical formulation of the molecular subcluster model, within the framework of the multiple scattering method, is presented. The model is applied to the study of the electronic structure of the FE(CN) IND. 6 POT. 4- ion. The calculations show that one of the main drawback of the multiple scattering method (the unphysical charge transfer to the interatomic region) is corrected. The model leads to molecular charge distributions with a good degree of physical realism. The interpretations of the X-ray photoelectron spectrum and the optical transitions for the ion, based on the proposed model, are in good agreement with the experimental results. The calculations carried out in this work show that the molecular subcluster model can be applied to a wide range of systems.