Increasing the Bandwidth of Resonant Gravitational Antennas: The Case of Explorer

Astone, P.; Babusci, D.; Bassan, M.; Carelli, P.; Cavallari, G.; Coccia, E.; Cosmelli, C.; D’Antonio, S.; Fafone, V.; Fauth, A. C.; Federici, Graziana; Giordano, G.; Marini, A.; Minenkov, Y.; Modena, I.; Modestino, G.; Moleti, Arturo; Pallottino, G. V.; Pizzella, G.; Quintieri, L.; Rocchi, A.; Ronga, F.; Terenzi, R.; Torrioli, G.; Visco, M.

doi:10.1103/physrevlett.91.111101

Cited by 45 publications

(22 citation statements)

References 19 publications

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“…the detection principle was based on the GW-induced resonant excitation of vibrational modes of metal cylinders. cryogenically cooled devices reached strain sensitivities of about h = 10 − 18 around a kilohertz, over a band width of a few Hz, in the 1990s and have been further improved since then [89][90][91][92] . today, the most sensitive instruments are laser interferometers with kilometre size arm lengths.…”

Section: Box 1 Past and Present Gw Detectorsmentioning

confidence: 99%

Quantum metrology for gravitational wave astronomy

et al. 2010

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einstein's general theory of relativity predicts that accelerating mass distributions produce gravitational radiation, analogous to electromagnetic radiation from accelerating charges. these gravitational waves (GWs) have not been directly detected to date, but are expected to open a new window to the universe once the detectors, kilometre-scale laser interferometers measuring the distance between quasi-free-falling mirrors, have achieved adequate sensitivity. recent advances in quantum metrology may now contribute to provide the required sensitivity boost. the so-called squeezed light is able to quantum entangle the high-power laser fields in the interferometer arms, and could have a key role in the realization of GW astronomy. When Galileo Galilei pointed his telescope towards the sky 400 years ago, he discovered events that had never been seen before. In subsequent centuries, a variety of telescopes were invented, covering a large part of the electromagnetic spectrum. These telescopes enabled observations that now form the basis of our understanding of the origin and the evolution of the Universe. Einstein's general theory of relativity, quite often simply 'general relativity' 1 , predicts the existence of a completely different kind of radiation, the so-called gravitational waves (GWs). As electromagnetic radiation is generated by acceleration of charges, so are GWs produced by accelerating mass distributions, such as supernova explosions or binary neutron stars that spiral into each other. GWs may also be emitted by objects that are electromagnetically dark, black holes, for example. Instruments that can directly observe GWs may well be able to 'light up' the dark side of our Universe. The analysis of the waves' spectrum and their time evolution will provide information about the nature of astrophysical and cosmological events that produced the waves. So far, GWs have not been directly observed.Suitable telescopes for GW astronomy are kilometre-scale laser interferometers that measure the distance between quasi-free-falling mirrors. This measurement can be used to infer changes of spacetime curvature. Current GW detectors are already able to measure extremely small changes of distance with strain sensitivity down to the order of 10 − 22. However, quantum physics imposes a fundamental limit on measurement sensitivity, in particular, in terms of photon-counting noise. In the past, the GW signal with respect to the photon-counting noise could only be increased by increasing the light power. Unfortunately, increasing light power will eventually produce measurable quantum radiation pressure noise. In addition it also increases the thermal load inside the detector and is problematic with respect to the concept of overall low noise. Squeezed light avoids these problems by increasing the measurement sensitivity without increasing the light power. The application of squeezed light is a quantum technology. Injected into an interferometer, it entangles the high-power laser fields in the interferometer arms. The photon...

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Section: Box 1 Past and Present Gw Detectorsmentioning

confidence: 99%

Quantum metrology for gravitational wave astronomy

et al. 2010

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“…Resonant transducers are used on resonant detectors, either bars or spheres [1,3,25], in order to improve their sensitivity and bandwidth. We consider here the same type of transducers as displacement sensors.…”

Section: B Sphere With N Resonant Transducersmentioning

confidence: 99%

Complete model of a spherical gravitational wave detector with capacitive transducers: Calibration and sensitivity optimization

Gottardi

2007

Phys. Rev. D

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We report the results of a detailed numerical analysis of a real resonant spherical gravitational wave antenna operating with six resonant two-mode capacitive transducers read out by superconducting quantum interference devices (SQUID) amplifiers. We derive a set of equations to describe the electro-mechanical dynamics of the detector. The model takes into account the effect of all the noise sources present in each transducer chain: the thermal noise associated with the mechanical resonators, the thermal noise from the superconducting impedance matching transformer, the back-action noise and the additive current noise of the SQUID amplifier. Asymmetries in the detector signal-to-noise ratio and bandwidth, coming from considering the transducers not as point-like objects but as sensor with physically defined geometry and dimension, are also investigated. We calculate the sensitivity for an ultracryogenic, 30 ton, 2 meter in diameter, spherical detector with optimal and non-optimal impedance matching of the electrical read-out scheme to the mechanical modes. The results of the analysis is useful not only to optimize existing smaller mass spherical detector like MiniGrail, in Leiden, but also as a technological guideline for future massive detectors. Furthermore we calculate the antenna patterns when the sphere operates with one, three and six transducers. The sky coverage for two detectors based in The Netherlands and Brasil and operating in coincidence is also estimated. Finally, we describe and numerically verify a calibration and filtering procedure useful for diagnostic and detection purposes in analogy with existing resonant bar detectors.

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“…below the superconducting (s) transition critical temperature T c 0.9 K. During this run, an unexpectedly large number of events with very large amplitude were detected. This result suggested an anomaly either in the thermo-acoustic model or in the cosmic ray interactions [31]. However the observation was not confirmed in the 2001 run with Nautilus at T = 1.5 K [29] and therefore we formulated the hypothesis that the unexpected behavior was due to the superconducting state of the material.…”

Section: The Thermo-acoustic Modelmentioning

confidence: 83%

Dark matter searches using gravitational wave bar detectors: Quark nuggets and newtorites

Bassan

Coccia

D’Antonio

et al. 2016

Astroparticle Physics

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Many experiments have searched for supersymmetric WIMP dark matter, with null results. This may suggest to look for more exotic possibilities, for example compact ultra-dense quark nuggets, widely discussed in literature with several different names. Nuclearites are an example of candidate compact objects with atomic size cross section. After a short discussion on nuclearites, the result of a nuclearite search with the gravitational wave bar detectors Nautilus and Explorer is reported. The geometrical acceptance of the bar detectors is 19.5 m(2) sr, that is smaller than that of other detectors used for similar searches. However, the detection mechanism is completely different and is more straightforward than in other detectors. The experimental limits we obtain are of interest because, for nuclearites of mass less than 10(-5) g, we find a flux smaller than that one predicted considering nuclearites as dark matter candidates. Particles with gravitational only interactions (newtorites) are another example. In this case the sensitivity is quite poor and a short discussion is reported on possible improvements. (C) 2016 Elsevier B.V. All rights reserved

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Increasing the Bandwidth of Resonant Gravitational Antennas: The Case of Explorer

Cited by 45 publications

References 19 publications

Quantum metrology for gravitational wave astronomy

Quantum metrology for gravitational wave astronomy

Complete model of a spherical gravitational wave detector with capacitive transducers: Calibration and sensitivity optimization

Dark matter searches using gravitational wave bar detectors: Quark nuggets and newtorites

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