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Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 119-124). Also available in electronic version.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 80-81). Also available in electronic version.

An Xipo = 低能电子能量损失谱中多重散射效应的修正 / 安西坡. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (leaves 55-56). / Text in English; abstracts in English and Chinese. / An Xipo = Di neng dian zi neng liang sun shi pu zhong duo zhong san she xiao ying de xiu zheng / An Xipo. / Abstract --- p.i / 摘要 --- p.ii / Acknowledgement --- p.iii / Table of contents --- p.iv / Chapter Chapter 1: --- Introduction --- p.1 / Chapter Chapter 2: --- Background / Chapter 2.1 --- Theory of electron scattering --- p.3 / Chapter 2.1.1 --- Elastic scattering --- p.3 / Chapter 2.1.2 --- Inelastic scattering --- p.4 / Chapter 2.1.2.1 --- The bethe theory --- p.5 / Chapter 2.1.2.2 --- The dielectric formulation --- p.6 / Chapter 2.1.3 --- Excitation of out-shell electrons --- p.6 / Chapter 2.1.3.1 --- Volume plasmon and its dispersion --- p.6 / Chapter 2.1.3.2 --- Single electron excitation --- p.8 / Chapter 2.2 --- Single and multiple scattering process --- p.8 / Chapter Chapter 3 --- Fourier transform based deconvolution method / Chapter 3.1 --- Theory --- p.10 / Chapter 3.1.1 --- Derivation of the single scattering distribution (SSD) --- p.10 / Chapter 3.1.2 --- K-K analyais --- p.12 / Chapter 3.2 --- Effectiveness of the F-log algorithm and data interpretation --- p.13 / Chapter 3.2.1 --- Removal of the plural scattering using F-log --- p.13 / Chapter 3.2.2 --- Deduction of the dielectric function --- p.14 / Chapter 3.3 --- Shortcomings and limitations --- p.15 / Chapter 3.3.1 --- Spectrum collection range --- p.15 / Chapter 3.3.2 --- Artificial peaks in the low energy range (0-5 eV) --- p.18 / Chapter 3.3.3 --- Thin specimens --- p.19 / Chapter 3.3.4 --- Spectra taken at q>0 --- p.22 / Chapter Chapter 4 --- Direct deconvolution method / Chapter 4.1 --- Theory --- p.26 / Chapter 4.2 --- Results and discussion --- p.31 / Chapter 4.2.1 --- Results of the original direct deconvolution algorithm --- p.31 / Chapter 4.2.2 --- Results of the revised direct deconvolution algorithm --- p.32 / Chapter 4.2.2.1 --- Removal of the plural scattering of the spectra taken at zero momentum transfer --- p.32 / Chapter 4.2.2.2 --- Removal of the plural scattering of the spectra taken at q>0 --- p.38 / Chapter 4.2.3 --- Evaluation of the revised direct deconvolution algorithm --- p.39 / Chapter Chapter 5 --- Elastic-inelastic interaction multiple scattering correction / Chapter 5.1 --- Theory --- p.44 / Chapter 5.2 --- Solution --- p.46 / Chapter 5.3 --- Results and discussion --- p.49 / Chapter Chapter 6 --- Conclusions --- p.52 / Reference --- p.54 / Appendix: / Chapter A1 --- The F-log deconvolution program code / Chapter A2 --- The Kramer-Kronig analysis program code / Chapter A3 --- The revised F-log program code to make allowance for the collection range problem / Chapter A4 --- Program code to reconstruct the ZLP / Chapter A5 --- The direct deconvolution program code

We revisited an empirical relationship between the integrated volume depolar- ization ratio, oacc, and the effective multiple scattering factor, -n, on the basis of Monte Carlo simulations of spaceborne lidar backscatter associated with homogeneous wa- ter clouds. The relationship is found to be sensitive to the extinction coefficient and to the particle size. The layer integrated attenuated backscatter is also obtained. Comparisons made between the simulations and statistics derived relationships of the layer integrated depolarization ratio, oacc, and the layer integrated attenuated backscatter, -n, based on the measurement by the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite show that a cloud with a large effective size or a large extinction coefficient has a relatively large integrated backscatter and a cloud with a small effective size or a large extinction coefficient has a large integrated volume depolarization ratio. The present results also show that optically thin water clouds may not obey the empirical relationship derived by Y. X. Hu. and co-authors.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [153]-167).

Made available in DSpace on 2014-10-09T12:33:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:36Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:33:49Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:36Z (GMT). No. of bitstreams: 0 / O interesse na pesquisa de Lasers randômicos, meios dispersivos com alto ganho, tem crescido nos últimos anos em virtude das novas possibilidades advindas ao se trabalhar com estes sistemas, como emissões em bandas com baixo ganho, bicromaticidade, localização da luz em meios difusos e sistemas ópticos mais compactos. Nesse trabalho serão discutidos temas como espalhamento da luz por partículas, intensidade de retroespalhamento, ganho em meios desordenados e as transições energéticas do neodímio, correlacionando as emissões características obtidas nos experimentos com a teoria. Quanto aos resultados será apresentado a primeira observação de laser randômico com nanopó de Nd:YVO4 através de análise do comportamento da emissão espectral e temporal oriunda da transição 4F3/24I11/2 (1064 nm). Os resultados apresentam outra forma de analisar a cinética temporal da emissão de laser randômico, permitindo uma separação da fração de emissão estimulada e espontânea e comparação desse resultado com o estreitamento sutil da largura de linha, típico de lasers randômicos. As conversões ascendentes e saturação de ETU (conversão ascendente por transferência de energia) serão analisadas na mesma amostra, sendo todos os ajustes provenientes da literatura e de fundamental interesse, principalmente por se tratarem de um mecanismo de perda em lasers operando na região do infravermelho. Por fim, a emissão característica será avaliada pela técnica CBS (retroespalhamento coerente) para determinação da coerência do laser emitido e localização da luz neste meio difuso, com os resultados comparados aos da simulação. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Low observable technology is used in order to prevent detection, or to delay detection. Radar cross section is an important parameter in aircraft survivability since it measures how detectable an object is with radar. To find the radar cross section Maxwell's equations are solved numerically in the time-domain using a finite difference scheme. This numerical method called Finite Difference Time Domain is very suitable for structures including complex materials. However, this numerical method needs to be verified for large scale simulations, due to numerical dispersion errors. Therefore it is desirable to verify the accuracy of the numerical simulations. In this project, the analytical solution to the multiple scattering by two spheres is implemented using the T-matrix formulation. The analytical solution to the scattering problem is first validated with the analytical Mie-series solution then compared to the Finite Difference Time Domain implementation. The results imply that the difference between the numerical and analytical solution is larger for higher frequencies and larger computational volumes. / Smygteknik används för att förhindra detektering, eller för att fördröja detektion av ett flygplan. Radarmålarea är en viktig parameter för skyddsprestanda hos flygplan eftersom den mäter hur detekterbar ett föremål är med radar. För att hitta radarmålarean löses Maxwells ekvationer numeriskt i tidsdomänen med hjälp av ett finit differensschema. Den numeriska metoden som kallas Finita differensmetoden i tidsdomän, är mycket lämplig för strukturer med komplexa material. Den numeriska metoden behöver valideras för storskaliga simuleringar eftersom det förekommer felaktigheter på grund av den numeriska dispersionen. Därför är det önskvärt att kontrollera riktigheten av de numeriska simuleringarna. I detta projekt, är den analytiska lösningen till multipelspridning av två sfärer implementerad med hjälp av T-matrismetoden. Den analytiska lösningen på spridningsproblemet valideras först mot den analytiska Mie-serielösningen och sedan jämförs den med resultatet av simuleringarna med Finita differensmetoden i tidsdomän. Resultaten antyder att skillnaden mellan den numeriska och analytiska lösningen är större för högre frekvenser och större beräkningsvolymer.

The Muon Ionization Cooling Experiment (MICE) is the first technical demonstration of muon ionization cooling, using a prototype section of a Neutrino Factory cooling channel. MICE is currently under construction at the Rutherford-Appleton Laboratory in the UK and will make the first cooling measurements in 2015, in Step IV of the experimental programme. Cooling predictions in Monte Carlo simulations of Step IV were found to disagree with the predictions of the 'cooling formula', a widely-used approximation, by up to 30% in liquid hydrogen (LH2). This disagreement was shown to originate, largely, from the multiple scattering expression used in the cooling formula. It was necessary to go back to the fundamental physics of scattering to derive a more accurate expression that includes scattering from atomic electrons. A modified form of the cooling formula was derived using this expression and gave better agreement with the Monte Carlo in LH2. Predictions are given for the equilibrium emittance, using the new expression, for seven low Z materials at muon momenta of 140, 200 and 240 MeV/c. Theories which predict the distribution of multiple scattering angles are briefly reviewed, focusing on Moliere theory and its variants, which are the most widely-used theories. The distributions predicted by these theories are used in most Monte Carlo codes but their implementation is not transparent, especially regarding the treatment of scatters with atomic electrons, which are important in low Z materials. A simple Monte Carlo model to predict multiple scattering distributions was developed that correctly treats scatters off electrons. The model gives very good agreement with measurements by the MuScat Experiment. Investigations were made into the possibility of measuring multiple scattering in MICE Step IV, both with and without the magnetic field. Preliminary results suggest that measurements are easier with no magnetic field, where tracks are straight. Corrections to account for the resolution of the scintillating-fibre trackers are required in both cases, but these are substantially smaller when straight tracks are used.