Desenvolvimento de transdutores paramétricos de alta sensibilidade para o detector de ondas gravitacionais mario schenberg




- The main purpose of this work was to build a set of parametric transducers of reentrant cavity type with high sensitivity and pumped at to be used in the gravitational wave detector Mario Schenberg. These transducers will monitor the mechanical vibrations of the -diameter spherical antenna in the frequency range. Niobium with high Tantalum impurities and were tested and used as the material for this set of transducers. The membranes, which close the cavities, were made from silicon blades. Many cavities similar to the parametric transducer cavities were constructed and tested cryogenically to determine their resonant frequencies and non-loaded electrical quality factor related to the electromagnetic coupling. After machined, the cavities received a Niobium film in order to present superconductor performance. However, the effect of superconductivity was not observed due to the small thickness of the deposited films and/or the non-anodization of their internal surfaces, in order to prevent progressive oxidation. For those cavities made of Niobium with high Tantalum impurities, was obtained using a cover made with the same material. When those cavities were closed with a Niobium cover with Tantalum impurities below , the non-loaded electrical quality factor was . It was proved then, the effect of this impurity in the achievement of superconductivity. Using Niobium of high purity and a suitable surface treatment it is expected to obtain at 4.2K. Also a new 10GHz oscillator with an ultra-low phase noise was built and tested using a sapphire crystal at 77K. The results indicate that the sensitivity of the new transducers will be of the order of at . The experimental tests were performed in the laboratories of INPE, USP, CETUC-PUC-RJ, CTA, LNLS and University of Western Australia (UWA).


oscilador de micro-ondas gravitational wave detector klystron parametric transducer cavidade ressoante supercondutora mario schenberg phase noise superconducting cavity resonator ruído de fase klystron detector de ondas gravitacionais transdutor paramétrico

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