The maraging-steel blades of the Virgo super attenuator

Braccini, S.; Casciano, C.; Cordero, F.; Corvace, F; Sanctis, Massimo De; Franco, R.; Frasconi, F.; Majorana, E.; Paparo, G.; Passaquieti, R.; Rapagnani, P.; Ricci, F.; Righetti, D.; Solina, A.; Valentini, Renzo

doi:10.1088/0957-0233/11/5/304

Cited by 31 publications

(19 citation statements)

References 9 publications

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“…3 To be successful, the LIGO detectors must reach an extreme displacement sensitivity in the audio frequency band. At the low frequency end of this band (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20), the horizontal motion of the 40 kg fused silica mirrors, acting as test masses, must be only about 10 −19 m/ √ Hz. Since the detector is located on the ground, it employs complex seismic isolation systems to reduce the contamination of the sensitivity by local seismic activity.…”

Section: Introductionmentioning

confidence: 99%

“…The Advanced LIGO test mass suspension system, 5, 18 shown schematically in Fig. 1, consists of a quadruple pendulum for horizontal isolation and incorporates three stages of 50 cmlong cantilever spring pairs, made of maraging steel 10 for vertical isolation. The suspension wires are also made of maraging steel, with the exception of the lowest wires, which are made of fused silica bonded to the mirror, to reduce thermal noise.…”

Section: Introductionmentioning

confidence: 99%

“…In the Advanced LIGO suspension system, however, the cantilever and wires loads are solidly within the macroscopically elastic regime, specifically about 50% of the yield stress. 10 To the best of our knowledge, there has been no in-depth investigation for potential discrete, stochastic deviation from linear mechanical behavior in crystalline materials this far below the engineering yield stress. Nevertheless, we can borrow insights from the existing experiments and theories which have studied the problem in the plastic regime.…”

Section: Introductionmentioning

confidence: 99%

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An instrument to measure mechanical up-conversion phenomena in metals in the elastic regime

Vajente

Quintero

et al. 2016

Review of Scientific Instruments

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Physical aging of plastoferrites under tensile stress and its effect on microwave properties J. Appl. Phys. 104, 064108 (2008) Crystalline materials, such as metals, are known to exhibit deviation from a simple linear relation between strain and stress when the latter exceeds the yield stress. In addition, it has been shown that metals respond to varying external stress in a discontinuous way in this regime, exhibiting discrete releases of energy. This crackling noise has been extensively studied both experimentally and theoretically when the metals are operating in the plastic regime. In our study, we focus on the behavior of metals in the elastic regime, where the stresses are well below the yield stress. We describe an instrument that aims to characterize non-linear mechanical noise in metals when stressed in the elastic regime. In macroscopic systems, this phenomenon is expected to manifest as a non-stationary noise modulated by external disturbances applied to the material, a form of mechanical up-conversion of noise. The main motivation for this work is for the case of maraging steel components (cantilevers and wires) in the suspension systems of terrestrial gravitational wave detectors. Such instruments are planned to reach very ambitious displacement sensitivities, and therefore mechanical noise in the cantilevers could prove to be a limiting factor for the detectors' final sensitivities, mainly due to non-linear up-conversion of low frequency residual seismic motion to the frequencies of interest for the gravitational wave observations. We describe here the experimental setup, with a target sensitivity of 10 −15 m/ √Hz in the frequency range of 10-1000 Hz, a simple phenomenological model of the non-linear mechanical noise, and the analysis method that is inspired by this model. Published by AIP Publishing. [http://dx

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An instrument to measure mechanical up-conversion phenomena in metals in the elastic regime

Vajente

Quintero

et al. 2016

Review of Scientific Instruments

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“…"Maraging" steel has been used in place of standard steel for blade construction in order to minimize micro-creep effects [8] due to the high load applied. We used the same material to machine the suspension wires with nail-heads at both ends.…”

Section: The Seismic Filtersmentioning

confidence: 99%

The Seismic Superattenuators of the Virgo Gravitational Waves Interferometer

Accadia

Acernese

Antonucci

et al. 2011

Journal of Low Frequency Noise, Vibration and Active Control

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The Virgo experiment, located near Pisa, Italy, is a large laser Michelson interferometer aiming at the first direct detection of gravitational waves. The interferometer monitors the relative distance of its mirrors placed at the ends of two 3 km-long perpendicular arms. The goal is to measure spectral differential variations of the arm lengths of 10−18 m/Hz1/2 in the frequency range from 10 Hz to 10 kHz. Avoiding spurious motions of the optical components is therefore essential to detect gravitational waves. Since the ground motion is 9 orders of magnitude larger than the arm length variations induced by gravitational waves, the seismic noise is the dominant low frequency noise source for terrestrial gravitational wave interferometers. The seismic isolation is obtained suspending the mirrors by an 8-meter tall chain of cascaded mechanical filters, called “Superattenuator” (SA). The Superattenuator is a passive device acting as a low pass filter in all six degrees of freedom, capable of attenuating the ground motion by more than 10 orders of magnitude, starting from a few Hz. To further reduce the seismic disturbances, the filter chain is suspended from an actively stabilized platform that compensates for low frequency and large amplitude oscillations caused by the mechanical resonances of the chain. In this article we describe the Superattenuator together with its control system, and we report about its performance.

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“…If there are only few dislocations and blocking defects (as in the annealed state of a pure metal grain), dislocations can glide under stress across the entire crystal volume, and pile up at the edge of it, until the accumulated stress exceeds the material ultimate strength and grain cleavage ensues, with acoustic emission [19], crystal cleavage, and creep; this also happens if the applied stress is sufficient to allow dislocations to jump blocking defects [16,17].…”

Section: Introductionmentioning

confidence: 99%