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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

High sensitivity niobium parametric transducer for the Mario Schenberg gravitational wave detector

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de Paula, L. A. N. [1, 2] ; Ferreira, E. C. [3] ; Carvalho, N. C. [4] ; Aguiar, O. D. [3]
Total Authors: 4
[1] ITA, Dept Phys, Sao Jose Dos Campos - Brazil
[2] Univ Sao Paulo, Dept Mech & Mat Phys, Sao Paulo - Brazil
[3] Natl Inst Space Res INPE, Div Astrophys, Sao Jose Dos Campos - Brazil
[4] Univ Western Australia, Sch Phys, Crawley, WA 6009 - Australia
Total Affiliations: 4
Document type: Journal article
Source: Journal of Instrumentation; v. 10, MAR 2015.
Web of Science Citations: 6

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 similar to 3 mu 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 similar to 10(-22) Hz(-1/2) in the near future, making it possible to search for gravitational waves around 3.2 kHz. (AU)