A physical criterion for validating the method used to design mechanical impedance matchers for Mario Schenberg's transducers

Bortoli, F. S.; Frajuca, Carlos; Magalhães, Nadja S.; Duarte, Écio Naves

doi:10.1088/1742-6596/228/1/012011

Cited by 29 publications

(13 citation statements)

References 9 publications

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“…To this end, we used simulations made with a FEM (Finite Element Modeling) tool of the software SolidWorks Education (Edition 2010–2011/2010 SP2.1). A previous paper from the authors (Bortoli et al 2010) gave them some ideas on this approach.…”

Section: First Step In the Methodologymentioning

confidence: 99%

A method to design mechanical transducers for resonant‐mass gravitational wave detectors

2021

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In this work, a methodology to design two-mode mechanical transducers for the spherical resonant-mass gravitational wave detector SCHENBERG is presented. This detector uses microwave multiparametric sensors and has 17 mechanical modes together with 6 electromagnetic modes for the microwave cavities. These transducers, when placed on the spherical surface of the detector, must have an effective mass ratio between their modes constant to provide the better amplification and compose a resonant system that has characteristics necessary for the detection of gravitational waves. To meet this demand, the transducers must form a resonant system with exactly the same quadrupole frequencies of the sphere. This work describes how these transducers were designed using Finite Element Modeling (FEM).

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Section: First Step In the Methodologymentioning

confidence: 99%

A method to design mechanical transducers for resonant‐mass gravitational wave detectors

2021

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“…The approach in this work is to introduce masses in a cabling, with their number, sizes, and distribution analyzed in various combinations. The analysis included spectral displacement curves obtained for key points inserted in the models of these systems, which were simulated using finite element modelling (FEM) [21].…”

Section: The Dilution Refrigeratormentioning

confidence: 99%

“…Such motion excites the membrane of the resonant cavity where the microwaves are pumped into, generating side band signals that will carry information on the GW [19,20]. The microwaves reach the resonant cavities through cables that start outside the dewar and end at microstrip antennas [21,22]. Schematic view of the SCHENBERG detector; illustration by Xavier P. M. Gratens.…”

Section: Introductionmentioning

confidence: 99%

On the Dilution Refrigerator Thermal Connection for the SCHENBERG Gravitational Wave Detector

et al. 2020

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The resonant-mass gravitational wave detector SCHENBERG was designed by the Brazilian group Graviton to be sensitive to a central frequency nearing 3200 Hz and a bandwidth of 200 Hz. It has a spherical antenna weighing 1150 kg that is connected to the outer environment by a suspension system designed to attenuate local noise due to seism as well as other sources. Should a gravitational wave pass by the detector, the antenna is expected to vibrate. This motion will be monitored by six parametric transducers whose output signals will be digitally analyzed. In order to improve the sensitivity of the detector, it must be cooled down to the lowest possible temperature, and for this purpose a dilution refrigerator is planned to be implemented in the detector. It is known that such device produces vibration when operational, consequently introducing noise in the system. Using the finite elements method, this work investigates thermal connections between the dilution refrigerator and the sphere suspension that allow the detector to operate within its projected sensitivity. The finite elements method showed an attenuation of 240dB in the best-valued thermal connection.

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“…The first attempts to detect GWs started in the early 60s (Richard 1984) with resonant-mass detectors that were continuously improved during the following decades (Aguiar et al 2002;Andrade et al 2004;Bortoli et al 2010Bortoli et al , 2016Bortoli et al , 2019Frajuca et al 2000Frajuca et al , 2002Frajuca et al , 2004Frajuca et al , 2005Frajuca et al , 2006Frajuca et al , 2008Frajuca et al , 2012Magalhaes et al 1995Magalhaes et al , 1997aMagalhaes et al , 1997bMagalhaes et al , 2012Magalhaes et al , 2016Oliveira et al 2018;Ribeiro et al 2004). These investigations include works of the Graviton group.…”

Section: Introductionmentioning

confidence: 99%

The influence of rotation deceleration on the shape of a pulsar may reflect on the star's braking index

2021

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Pulsars are stars whose electromagnetic radiation is observed to pulsate in well-defined time intervals while they rotate as long as the electromagnetic signal is not emitted in the direction of the rotation axis. The frequencies of the pulses decay with time as quantified by the braking index (n). In the canonical model, n = 3 for all pulsars, but observational data yield n < 3. In this work, this model is modified to allow time change in the moment of inertia. According to that model, as the neutron star loses energy by the emission of electromagnetic radiation, its rotation decelerates under constant moment of inertia. Here, we propose that, as the rotation decelerates, the shape of the star changes due to an increasingly weaker centrifugal force that reduces its moment of inertia, a change that, under normal circumstances, would accelerate the star's rotation. In the case of pulsars, as the rotation decreases in view of electromagnetic energy loss, the rotation would decelerate less than in the canonical model, yielding a braking index less than three. This is a good result from our model, especially regarding stars with indices close to three. For lower indices, our model requires refinements as a complete explanation of braking index values probably demands that a series of phenomena be incorporated into the process.

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A physical criterion for validating the method used to design mechanical impedance matchers for Mario Schenberg's transducers

Cited by 29 publications

References 9 publications

A method to design mechanical transducers for resonant‐mass gravitational wave detectors

A method to design mechanical transducers for resonant‐mass gravitational wave detectors

On the Dilution Refrigerator Thermal Connection for the SCHENBERG Gravitational Wave Detector

The influence of rotation deceleration on the shape of a pulsar may reflect on the star's braking index

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