University, Diss., 2005--Köln.

Techn. Universiẗat, Diss., 2005--Berlin.

University, Diss., 2004--Köln.

<p> A technique has been developed for constructing low temperature germanium bolometers for use as detectors in the far infrared. Their performance has been evaluated both by measuring their responsivity and noise and comparing these with the theoretical values and also by using the bolometer in conjunction with a far infrared spectrophotometer to obtain spectra showing the theoretical resolution of 0.11 cm^-1 at 55 cm^-1 expected for this instrument.</p> / Thesis / Master of Science (MSc)

This Master thesis aims at designing, assembling and operating a prototypal luminescentbolometer containing a candidate with high Q-value (116Cd and 100Mo)for the study of the neutrinoless double- decay. The crystal is scintillating (with 116CdWO4 and Li2MoO4 compounds). The prototype is designed according to a simple thermal model and cooled down to 18 mK. Data analysis of the 116CdWO4 crystal determines the energy resolution (intrinsicand in the ROI) and the alpha/beta discrimination power. It includes a full interpretation of the background energy spectrum in terms of environmental radioactivity and an evaluation of the crystal radiopurity by the detection of internal contamination of the detector. An evaluation of the potential of a future experiment based on the 116CdWO4developed prototype is performed, ascertaining the feasibility of large scale experiments to search for neutrinoless double beta decay. The use of the thermal model of the detector response to interpret its bolometric behaviour and the study of future optimizations of the detector performance concludes this project.

The Sunyaev Zel'dovich effect (SZE) is a secondary distortion of the cosmic microwave background (CMB) spectrum produced by galaxy clusters that allows for measurements of intra-cluster gas properties. Current experiments are using large arrays of multiplexed transition-edge sensor bolometers to achieve the sensitivities required for SZE cluster surveys and targeted cluster SZE observations. This thesis describes the APEX-SZ experiment, the first instrument to produce scientific results from observations with such an array. The scientific motivation for the APEX-SZ experiment is discussed, followed by a description of the APEX-SZ experiment and frequency domain multiplexing technologies. We have developed a custom data reduction pipeline for the experiment which uses a variety of filters, both in the temporal and spatial domain to produce 1' resolution maps of the SZE at 150GHz. The results of data analysis for the Bullet cluster (lE0657-56) and Abell 2204 (A2204) are presented. Both clusters are assumed to be isothermal and in hydrostatic equilibrium, allowing a fit to an isothermal beta-model and subsequent mass fraction estimates. The maximum likelihood parameters and constant likelihood 68% confidence intervals are estimated using a Markov-Chain Monte Carlo method to sample the beta-model parameter space. We measure cluster gas mass fractions with r 2500 to be 0.140 +/- 0.035 and 0.058 +/- 0.035 for the Bullet cluster and A2204 respectively. The Bullet gas mass fraction is consistent with previous results from X-ray analysis. The gas mass fraction for A2204 does not agree well with other A2204 observations, however the large scatter in the gas mass fractions determined from previous X-ray and SZE analyses indicates that a more complex density model may be appropriate for this cluster.

Thesis (M.S.)--University of Wisconsin--Madison, 1965. / eContent provider-neutral record in process. Description based on print version record. Bibliography: l. 48.

Goal of this thesis is to study infrared detection by means of thermal. Theoretical part of this work gives an introduction to thermal detectors.

Plusieurs catégories de MEMS nécessitent un environnement sous vide pour fonctionner de manière optimale, tel le micro-bolomètre. Le fonctionnement optimal de ce détecteur, à la base des imageurs infrarouge non refroidis, nécessite qu’il soit thermiquement isolé, et donc qu’il évolue dans une atmosphère raréfiée (< 10-2 mbar). Le maintien sous vide d’une matrice bolométrique durant la durée de vie d'une dizaine d’années du composant est réalisé par une encapsulation dans un boîtier de très faible volume (de 0,5 à 30 µL).Cette encapsulation sous vide fait appel à deux techniques complémentaires : le scellement hermétique sous vide et l’intégration d’un dispositif d’absorption du gaz dans la cavité, appelé getter. La technique de scellement donnant un joint de scellement suffisamment hermétique (<10-14 atm.cm3.s-1) est la soudure métallique. Le getter est un film mince métallique à base de métaux de transition. Il acquiert une activité de sorption lorsqu’il est chauffé.Les procédés d’encapsulation sous vide de l’état de l’art permettent l’encapsulation de micro-bolomètres à des températures de 300°C. Mais il est fort probable que les futurs matériaux micro-bolométriques en cours de développement ne supporteront pas des températures de recuit supérieures à 280°C. Leur encapsulation demande donc la mise à disposition d’un nouveau procédé de scellement sous vide à plus basse température et d’un nouveau film getter s’activant aussi à basse température.Ces deux techniques ont par conséquent été développées, au moyen de caractérisations en laboratoire et de tests sur composants industriels. / Some kinds of MEMS like micro-bolometers require vacuum to operate optimally. This IR sensor is the cornerstone for uncooled infrared detection. Its best sensing capacity is achieved by thermal insulation, which is realized by placing it under vacuum (< 10-2 mbar). The vacuum is maintained throughout the camera lifetime thanks to a microvolume packaging (0.5 to 30 µL).The MEMS vacuum packaging implies the combination of two complementary technical solutions: first hermetic sealing, then getter device integration absorbing internal gas. The sealing technique retained (which enables leak rate <10-14 atm.cm3.s-1) is the metallic bonding. The getter is a thin transition metal film. When activated by an annealing, its surface traps gaseous molecules. The sorption process of the getter is ideally activated during the sealing process of the bonding.The typical temperature packaging process for micro-bolometers is 300°C. It is expected that sensibility of new types of micro-bolometers materials will be degraded if they are exposed to temperatures higher than 280°C. Consequently, their encapsulation require the elaboration of a new low temperature packaging technology.Such a technology has been developed based on experimental studies in laboratory and tests under industrial conditions.

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