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This thesis describes the development of a laser-cooling experiment aimed at efficient transfer of cold atoms over a short distance, for loading into a conservative atom trap. We detail the construction of a 3D magneto-optical trap (MOT) and perform characterisation measurements to optimise the number and temperature of the cold atoms. The atoms are launched vertically in a fountain from the MOT using a 'moving molasses' technique and a red-detuned far-off-resonant laser beam is used to guide them into an UHV chamber. Loading into the guiding beam is optimised with respect to the beam and MOT parameters. We demonstrate a maximum loading of 20% and guiding over a distance of more than 10 cm without loss of atoms. The atoms are delivered to the UHV chamber in a cloud with a transverse dimension of order 200 µm. We discuss the extension to continuous operation of the guided atomic fountain. The 3D MOT is replaced by a funnel with 2D trapping and 3D cooling which continuously extracts the cold atoms using moving molasses. A comparison between the flux of guided atoms obtained in a pulsed fashion from the 3D MOT and continuously from the funnel indicate that the pulsed case is a factor of ten more efficient. The difference is due to inferior loading from the funnel. The optically guided fountain is used to load an optical dipole trap in the UHV chamber, using an 'optical trap door'. No additional cooling is required. The dynamics of the atoms in the optical dipole trap are studied. We discuss multiple loading of a conservative trap with the view of accumulating more atoms than can be obtained in a MOT.

Submitted by Jean Medeiros (jeanletras@uepb.edu.br) on 2016-04-27T12:51:25Z No. of bitstreams: 1 PDF - Juliana Cardoso Herculano.pdf: 2901982 bytes, checksum: 1eb37789ca96855b4c63bd56d9a06682 (MD5) / Made available in DSpace on 2016-04-27T12:51:25Z (GMT). No. of bitstreams: 1 PDF - Juliana Cardoso Herculano.pdf: 2901982 bytes, checksum: 1eb37789ca96855b4c63bd56d9a06682 (MD5) Previous issue date: 2015-05-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Temperature values around 90 km height were used to investigate a possible relationship between the variations of temperature and solar flux during the solar cycle 23. The temperature data were obtained from the meteoric signal decay time in Cachoeira Paulista (22.7 ° S, 45.0 ° W). To find a possible long-term trend and variations induced by solar activity in annual average temperatures, the data sets were analyzed by multiple linear regression. It was observed that over time the temperature obtained by the two methods show variations. The variation appears to be most pronounced for the temperatures obtained by the gradient method, in which the amplitudes are larger, as well as the respective standard deviations. To analyze the behavior of temperature during solar cycle 23, the seasonally adjusted annual averages, after eliminating the influence of solar activity, they were used and the linear trend was estimated. The average temperature calculated by the model pressure tends to increase about 0.035 K / year when the entire period of observation is considered. However, for the period between maximum and solar minimum the average annual temperature has a tendency of increase of 0.166 K / year. The results show that the annual average temperature of seasonally adjusted after removal of the effects due to solar flux obtained by the gradient method would be higher than the original period for the solar decline. It is noted that the annual temperature seasonally adjusted virtually no change when t he time trend is removed, which may indicate that the annual temperature deseasonalized obtained by the gradient method are strongly affected by the solar flux. / Valores da temperatura em torno de 90 km de altura foram usados para investigar uma possível relação entre as variações da temperatura e o fluxo solar durante o ciclo solar 23. Os dados de temperatura foram obtidos a partir do tempo de decaimento do sinal meteórico em Cachoeira Paulista (22,7°S, 45,0°O). Para encontrar uma possível tendência de longo prazo e variações induzidas pela atividade solar nas médias anuais das temperaturas, as séries de dados foram submetidas à análise de regressão linear múltipla. Observou-se que ao longo do tempo as temperaturas obtidas através dos 2 métodos apresentam variações. A variação mostra-se mais notória para as temperaturas obtidas pelo método do gradiente, em que as amplitudes são maiores, assim como os respectivos desvios padrão. Para analisar o comportamento da temperatura durante o ciclo solar 23, as médias anuais dessazonalizadas, após a eliminação da influência da atividade solar, foram utilizadas e a tendência linear foi estimada. A temperatura média calculada pelo modelo de pressão tende a aumentar cerca de 0,035 K/ano quando todo o período de observação é considerado. Contudo, para o período compreendido entre máximo e o mínimo solar a temperatura média anual apresenta uma tendência de aumento de 0,166 K/ano. Os resultados mostram que as médias anuais das temperaturas dessazonalizadas após a remoção dos efeitos devido ao fluxo solar, obtidas pelo método do gradiente, seriam mais elevadas do que as originais para o período de declínio solar. Verifica-se que as temperaturas anuais dessazonalizadas praticamente não mudam quando a tendência temporal é removida, o que pode indicar que as temperaturas anuais dessazonalizadas obtidas pelo método do gradiente são fortemente afetadas pelo fluxo solar.

The heat capacity of 3He adsorbed on Grafoil (exfoilated graphite) preplated with four layers of 4He was measured between 1 and 50mK. The heat capacity was found to be linear up to 4OmK. At 3He surface densities below 4nm-2 two dimensional Fermi liquid behaviour was found and values of the hydrodynamic effective mass and Landau parameter Ff inferred. Subsequent steps in the heat capacity as a function of coverage were taken as evidence of independent 2D Fermi fluids. A low field DC SQUID pulsed NMR spectrometer was developed for future studies of magnetic order in 2D solid 3He films at ultralow temperatures