author = "Paula, L. A. N. and Ferreira, Elvis Camilo and Carvalho, N. C. and 
                         Aguiar, Odylio Denys de",
          affiliation = "{Instituto Tecnol{\'o}gico de Aeron{\'a}utica (ITA)} and 
                         {Instituto Nacional de Pesquisas Espaciais (INPE)} and {University 
                         of Western Australia} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "High sensitivity niobium parametric transducer for the Mario 
                         Schenberg gravitational wave detector",
              journal = "Journal of Instrumentation",
                 year = "2015",
               volume = "10",
             keywords = "Instrument optimisation, resonant deterctors, modeling of 
                         microwave systems.",
             abstract = "Parametric transducers can work below the quantum limit of 
                         sensitivity for resonant mass gravitational wave detectors. This 
                         makes them a promising alternative for electromechanical 
                         transductance for such detectors. These transducers consist of a 
                         reentrant superconducting niobium cavity coupled to a mass-spring 
                         system with three mechanical modes. These cavities have a central 
                         post responsible for creating a narrow axial gap between its top 
                         and the cavity wall, which is a resonant membrane. Their 
                         displacement sensitivity (df/dx) increases as the gap spacing 
                         decreases. However, this is not a linear relationship and the 
                         dimensioning of the cavity becomes critical if the gap is of the 
                         order of a few microns. In this paper, we describe how to obtain a 
                         gap spacing of ~ 3 \μ m and also the development of 
                         parametric transducers that will be employed in the coming 
                         experimental runs of the Schenberg gravitational wave antenna. 
                         Mechanical thinning methods were performed followed by mechanical 
                         and electrical frequency measurements to tune the device to 
                         operate at the required frequencies. The main results present 
                         better frequency stability and an improvement of df/dx by one 
                         order of magnitude higher than the preceding models. These results 
                         will allow us to reach the quantum limit of detector sensitivity 
                         of ~ 10\−22 Hz\−1/2 in the near future, making it 
                         possible to search for gravitational waves around 3.2 kHz.",
                  doi = "10.1088/1748-0221/10/03/P03001",
                  url = "http://dx.doi.org/10.1088/1748-0221/10/03/P03001",
                 issn = "1748-0221",
             language = "en",
        urlaccessdate = "16 jan. 2021"