O detector de ondas gravitacionais Mário Schenberg consiste de uma massa ressonante esférica de Cu(94%)Al(6%) com 65cm de diâmetro, pesando aproximadamente 1,15T, com um Q mecânico da ordem de 106 e todos os sistemas que possibilitam o seu funcionamento como detector de ondas gravitacionais. O projeto do detector prevê para este uma sensibilidade da ordem de 10-20 (em deformação). Para isso dependerá da eficiência dos sistemas vibracionais que utiliza. Neste trabalho os casadores mecânicos de impedância, foram simulados com um programa de elementos finitos e otimizados quanto à sua banda e acoplamento vibracional. Foi feita a análise do sistema de isolamento vibracional da nova suspensão, por meio da resposta em frequência do ruído sísmico na superfície da esfera, nos mesmos locais onde estão conectados os transdutores. Foi proposto um projeto novo para atenuar os ruídos provenientes do cabeamento que conduz os sinais de micro-ondas. Foi avaliado o efeito do ruído sísmico introduzido na suspensão e na esfera, também nos locais dos transdutores, utilizando este novo projeto. É apresentado um projeto para a conexão térmica do refrigerador por diluição, que a análise por simulação numérica demonstrou ser eficaz. A modelagem para análise vibracional é a melhor já feita para detectores esféricos, isto se comparada às que foram encontrados na literatura. Os resultados alcançados demonstraram que as atenuação em todos os sistemas analisados são adequadas às metas do projeto do detector Mário Schenberg, ou seja, os ruídos remanescentes estão abaixo do ruído térmico esperado na temperatura de 50mK. / The Gravitational Wave detector Mario Schenberg consist of a spherical resonant-mass made of CuAl(6%) with 65 cm diameter e weighting 1.15 Ton, with a Mechanical quality factor of about 106 and all the systems that allows it to word as a gravitational wave detector. The detector design was made for it to reach a sensitivity of 10-20 (strain sensitivity). To reach this goal it depends on the efficiency of the it vibrational systems. In this work the transducers mechanical impedance matchers were simulated with a finite element program and optimized in its band and vibrational coupling. A analysis of the vibrational isolation of the new suspension was made by the frequency response of the seismic noise on the sphere surface, on the same places where they will be connected to the transducers. A new design for attenuation of the noise due to microwave cabling was proposed. The seismic noise introduced on the suspension and on the sphere was simulated using this new design. A design for the dilution refrigerator thermal connection is presented, and its performance is measured in a analysis in a finite element moddeling, and showed itself efficienty. This vibration model for the detector is the best one ever made for spherical detectors, if compared to the literature. Results obtained showed that the atennuation in all the analysed systems are compatible to the Mário Schenberg detector design goals, it means that, the remaining noises are below the expected thermal noise at the temperature of 50 mK.

The efficiency of different spectroscopic techniques are examined through four different approaches: detailed analysis of IR spectra from the APOGEE database and examination of persistence, observing extremely metal-poor stars using the Plaskett telescope at the DAO, three analyses of various applications of machine learning in astronomy, and efficient transmission of light through optical fibres. Through the first study, the technical effects of persistence in the APOGEE's IR spectra are examined, and a new technique for removing the persistence is introduced. Most of the globular cluster Pal 1's spectra in the APOGEE database are affected by persistence. Therefore, the Pal 1 spectra are corrected for the persistence and their stellar abundances are determined independently from the APOGEE's pipeline, ASPCAP. Our results for the known members of Pal 1 were in a close agreement with the results from Sakari et al. (2011). Comparison between the results from the corrected and the original spectra suggest that the persistence could have a critical effect on the results. The second study of this thesis focused on observations of extremely metal-poor (EMP) stars from the Pristine survey. Through the DAO-Pristine project, we narrowed down the initial list of the Pristine survey by observing over 50 targets during 25 observing nights. The Ca II triplet absorption lines of the observed targets were examined and used for estimating the metallicity of the objects. Twelve candidate EMP stars with weak Ca II triplet lines are chosen from the observed targets. These candidate EMP stars will be observed with larger telescopes for more accurate determination of their metallicity. This thesis also presents the result of a threefold analysis for using machine learning techniques in astronomy. The supervised machine learning methods are used for determination of the stellar parameters of stars using their raw spectra, and unsupervised machine learning methods are used for classification of supernovae Type Ia from their calibrated spectra. The supervised analysis of the IR and optical spectra suggested that the StarNet neural network (Fabbro et al. 2017) can predict the stellar parameters of the APOGEE database and synthetic spectra, efficiently and accurately. The effect of persistence in the StarNet's results are examined, and we showed that the persistence does not have a critical effect on the overall performance of the StarNet. In addition, multiple unsupervised machine learning techniques such as K-mean and Self Organizing Maps (SOMs) are used for classification of the supernovae Type Ia spectra. The preliminary results suggest that a minimum of three subclasses of supernovae Type Ia can be found from our data, which are consistent with the previous studies. Finally, this thesis presents our final results for an optical system we designed for the MSE project. At UVic, we have used the standard collimated beam method, or "ring test," to measure the Focal Ratio Degradation (FRD) of MSE-like fibres. The FRD of the system is determined from the ratio of the Full Width Half Maximum (FWHM) to the radius of the ring. Early ring test results from a sample of MSE-like fibres show an FRD of 3.7%, which meets the MSE science requirement (i.e. FRD < 5% at f/2). Also, we have automated the ring test for fast, repeatable, and efficient measurements of an individual fibre in multi-fibre bundles. Our future tests will include automated non-static fibres in preparation for the MSE build phases. / Graduate

O detector de ondas gravitacionais Mário Schenberg consiste de uma massa ressonante esférica de Cu(94%)Al(6%) com 65cm de diâmetro, pesando aproximadamente 1,15T, com um Q mecânico da ordem de 106 e todos os sistemas que possibilitam o seu funcionamento como detector de ondas gravitacionais. O projeto do detector prevê para este uma sensibilidade da ordem de 10-20 (em deformação). Para isso dependerá da eficiência dos sistemas vibracionais que utiliza. Neste trabalho os casadores mecânicos de impedância, foram simulados com um programa de elementos finitos e otimizados quanto à sua banda e acoplamento vibracional. Foi feita a análise do sistema de isolamento vibracional da nova suspensão, por meio da resposta em frequência do ruído sísmico na superfície da esfera, nos mesmos locais onde estão conectados os transdutores. Foi proposto um projeto novo para atenuar os ruídos provenientes do cabeamento que conduz os sinais de micro-ondas. Foi avaliado o efeito do ruído sísmico introduzido na suspensão e na esfera, também nos locais dos transdutores, utilizando este novo projeto. É apresentado um projeto para a conexão térmica do refrigerador por diluição, que a análise por simulação numérica demonstrou ser eficaz. A modelagem para análise vibracional é a melhor já feita para detectores esféricos, isto se comparada às que foram encontrados na literatura. Os resultados alcançados demonstraram que as atenuação em todos os sistemas analisados são adequadas às metas do projeto do detector Mário Schenberg, ou seja, os ruídos remanescentes estão abaixo do ruído térmico esperado na temperatura de 50mK. / The Gravitational Wave detector Mario Schenberg consist of a spherical resonant-mass made of CuAl(6%) with 65 cm diameter e weighting 1.15 Ton, with a Mechanical quality factor of about 106 and all the systems that allows it to word as a gravitational wave detector. The detector design was made for it to reach a sensitivity of 10-20 (strain sensitivity). To reach this goal it depends on the efficiency of the it vibrational systems. In this work the transducers mechanical impedance matchers were simulated with a finite element program and optimized in its band and vibrational coupling. A analysis of the vibrational isolation of the new suspension was made by the frequency response of the seismic noise on the sphere surface, on the same places where they will be connected to the transducers. A new design for attenuation of the noise due to microwave cabling was proposed. The seismic noise introduced on the suspension and on the sphere was simulated using this new design. A design for the dilution refrigerator thermal connection is presented, and its performance is measured in a analysis in a finite element moddeling, and showed itself efficienty. This vibration model for the detector is the best one ever made for spherical detectors, if compared to the literature. Results obtained showed that the atennuation in all the analysed systems are compatible to the Mário Schenberg detector design goals, it means that, the remaining noises are below the expected thermal noise at the temperature of 50 mK.