Showing papers by "Mirko Prato published in 2011"
University of Glasgow1, University of Salerno2, Max Planck Society3, University of Southampton4, University of Paris-Sud5, University of Nice Sophia Antipolis6, Washington State University7, Istituto Nazionale di Fisica Nucleare8, University of Warsaw9, University of Naples Federico II10, University of Birmingham11, Cardiff University12, University of Rome Tor Vergata13, Moscow State University14, California Institute of Technology15, VU University Amsterdam16, fondazione bruno kessler17, Leibniz University of Hanover18, University of Cambridge19, University of Tübingen20, University of Urbino21, University of Jena22, University of the Balearic Islands23, Northwestern University24, University of Minnesota25, University of Savoy26, Pennsylvania State University27, University of Pisa28, Roma Tre University29, Sapienza University of Rome30, University of Mississippi31
TL;DR: In this article, a special focus is set on evaluating the frequency band below 10 Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates, including the most relevant fundamental noise contributions.
Abstract: Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope (ET), a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this paper we describe sensitivity models for ET and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10 Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.
682 citations
TL;DR: In this article, the authors describe the current state and future evolution of the Virgo gravitational wave detector, realized by the European Gravitational Observatory in Cascina near Pisa in Italy.
Abstract: We describe the present state and future evolution of the Virgo gravitational wave detector, realized by the Virgo Collaboration at the European Gravitational Observatory, in Cascina near Pisa in Italy. We summarize basic principles of the operation and the design features of the Virgo detector. We present the sensitivity evolution due to a series of intermediate upgrades called Virgo+ which is being completed this year and includes new monolithic suspensions. We describe the present scientific potential of the detector. Finally we discuss the plans for the second generation of the detector, called Advanced Virgo, introducing its new features, the expected sensitivity evolution and the scientific potential. Status of Virgo 4 Figure 1. An aerial view of the Virgo gravitational wave detector. The detector Virgo is located in the countryside of Commune of Cascina, a few km south of the city of Pisa, Tuscany.
217 citations
20 May 2011
TL;DR: In this article, the conceptual design of a third generation gravitational wave observatory named the Einstein Telescope (ET) has been described with the support of the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n 211743.
Abstract: This document describes the Conceptual Design of a third generation gravitational wave observatory named Einstein Telescope (“ET”). The design of this new research infrastructure has been realised with the support of the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement n 211743. In this document are described the fundamental design options, the site requirements, the main technological solutions, a rough evaluation of the costs and a schematic time plan.
192 citations
TL;DR: In this paper, the authors present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first 9 months of the fifth science run of the LIGO.
Abstract: We present direct upper limits on gravitational wave emission from the Crab pulsar using data from the first 9 months of the fifth science run of the Laser Interferometer Gravitational-wave Observatory (LIGO). These limits are based on two searches. In the first we assume that the gravitational wave emission follows the observed radio timing, giving an upper limit on gravitational wave emission that beats indirect limits inferred from the spin-down and braking index of the pulsar and the energetics of the nebula. In the second we allow for a small mismatch between the gravitational and radio signal frequencies and interpret our results in the context of two possible gravitational wave emission mechanisms.
160 citations
01 Jun 2011
105 citations
TL;DR: In this paper, a low-latency analysis pipeline was used to identify and localize GW event candidates and to request images of targeted sky locations, where a catalog of nearby galaxies and Milky Way globular clusters were used to select the most promising sky positions to be imaged.
Abstract: Aims. A transient astrophysical event observed in both gravitational wave (GW) and electromagnetic (EM) channels would yield rich scientific rewards. A first program initiating EM follow-ups to possible transient GW events has been developed and exercised by the LIGO and Virgo community in association with several partners. In this paper, we describe and evaluate the methods used to promptly identify and localize GW event candidates and to request images of targeted sky locations.
Methods. During two observing periods (Dec 17 2009 to Jan 8 2010 and Sep 2 to Oct 20 2010), a low-latency analysis pipeline was used to identify GW event candidates and to reconstruct maps of possible sky locations. A catalog of nearby galaxies and Milky Way globular clusters was used to select the most promising sky positions to be imaged, and this directional information was delivered to EM observatories with time lags of about thirty minutes. A Monte Carlo simulation has been used to evaluate the low-latency GW pipeline's ability to reconstruct source positions correctly.
Results. For signals near the detection threshold, our low-latency algorithms often localized simulated GW burst signals to tens of square degrees, while neutron star/neutron star inspirals and neutron star/black hole inspirals were localized to a few hundred square degrees. Localization precision improves for moderately stronger signals. The correct sky location of signals well above threshold and originating from nearby galaxies may be observed with ~50% or better probability with a few pointings of wide-field telescopes.
104 citations
TL;DR: Two directional searches for persistent GWs using data from the LIGO S5 science run are performed: one optimized for pointlike sources and one for arbitrary extended sources, finding no evidence to support the detection of GWs.
Abstract: The gravitational-wave (GW) sky may include nearby pointlike sources as well as stochastic backgrounds. We perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. Finding no evidence to support the detection of GWs, we present 90% confidence level (C.L.) upper-limit maps of GW strain power with typical values between 2-20×10-50strain2Hz-1 and 5-35×10-49strain2Hz-1sr-1 for pointlike and extended sources, respectively. The latter result is the first of its kind. We also set 90% C.L. limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN 1987A and the Galactic center as low as ≈7×10-25 in the most sensitive frequency range near 160 Hz.
97 citations
TL;DR: The winners and runners-up in this competition will be announced at a later date, but it is likely that some of the winners will have already been announced in the competition.
Abstract: We present the first modeled search for gravitational waves using the complete binary black hole gravitational waveform from inspiral through the merger and ringdown for binaries with negligible component spin. We searched approximately 2 years of LIGO data taken between November 2005 and September 2007 for systems with component masses of 1-99 solar masses and total masses of 25-100 solar masses. We did not detect any plausible gravitational-wave signals but we do place upper limits on the merger rate of binary black holes as a function of the component masses in this range. We constrain the rate of mergers for binary black hole systems with component masses between 19 and 28 solar masses and negligible spin to be no more than 2.0 per Mpc^3 per Myr at 90% confidence.
83 citations
TL;DR: In this paper, the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars, were presented.
Abstract: Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are thought to be magnetars: neutron stars powered by extreme magnetic fields. These rare objects are characterized by repeated and sometimes spectacular gamma-ray bursts. The burst mechanism might involve crustal fractures and excitation of non-radial modes which would emit gravitational waves (GWs). We present the results of a search for GW bursts from six galactic magnetars that is sensitive to neutron star f-modes, thought to be the most efficient GW emitting oscillatory modes in compact stars. One of them, SGR 0501+4516, is likely ~1 kpc from Earth, an order of magnitude closer than magnetars targeted in previous GW searches. A second, AXP 1E 1547.0-5408, gave a burst with an estimated isotropic energy >1044 erg which is comparable to the giant flares. We find no evidence of GWs associated with a sample of 1279 electromagnetic triggers from six magnetars occurring between 2006 November and 2009 June, in GW data from the LIGO, Virgo, and GEO600 detectors. Our lowest model-dependent GW emission energy upper limits for band- and time-limited white noise bursts in the detector sensitive band, and for f-mode ringdowns (at 1090 Hz), are 3.0 × 1044 d 2 1 erg and 1.4 × 1047 d 2 1 erg, respectively, where $d_\mathrm{1} = \frac{d_{\mathrm{0501}}}{1\,\mathrm{kpc}}$ and d 0501 is the distance to SGR 0501+4516. These limits on GW emission from f-modes are an order of magnitude lower than any previous, and approach the range of electromagnetic energies seen in SGR giant flares for the first time.
80 citations
TL;DR: In this article, direct upper limits on continuous gravitational wave emission from the Vela pulsar using data from the Virgo detector's second science run were obtained using three independent methods.
Abstract: We present direct upper limits on continuous gravitational wave emission from the Vela pulsar using data from the Virgo detector's second science run. These upper limits have been obtained using three independent methods that assume the gravitational wave emission follows the radio timing. Two of the methods produce frequentist upper limits for an assumed known orientation of the star's spin axis and value of the wave polarization angle of, respectively, $1.9\ee{-24}$ and $2.2\ee{-24}$, with 95% confidence. The third method, under the same hypothesis, produces a Bayesian upper limit of $2.1\ee{-24}$, with 95% degree of belief. These limits are below the indirect {\it spin-down limit} of $3.3\ee{-24}$ for the Vela pulsar, defined by the energy loss rate inferred from observed decrease in Vela's spin frequency, and correspond to a limit on the star ellipticity of $\sim 10^{-3}$. Slightly less stringent results, but still well below the spin-down limit, are obtained assuming the star's spin axis inclination and the wave polarization angles are unknown.
78 citations
TL;DR: In this article, the methods used to determine the parameters for sensitivity estimation and gravitational wave reconstruction are described and the main quantities to be calibrated are the frequency response of the mirror actuation and the sensing of the output power.
Abstract: The Virgo detector is a kilometer-length interferometer for gravitational wave detection located near Pisa (Italy). During its second science run (VSR2) in 2009, 6 months of data were accumulated with a sensitivity close to its design. In this paper, the methods used to determine the parameters for sensitivity estimation and gravitational wave reconstruction are described. The main quantities to be calibrated are the frequency response of the mirror actuation and the sensing of the output power. Focus is also put on their absolute timing. The monitoring of the calibration data and the parameter estimation with independent techniques are discussed to provide an estimation of the calibration uncertainties. Finally, the estimation of the Virgo sensitivity in the frequency domain is described and typical sensitivities measured during VSR2 are shown.
TL;DR: In this paper, the authors present a survey of the state-of-the-art work in this area, including the following: A.A. Adhikari, P.B. Abadie, B.Babak, A.C. Anderson, W.M. Brandes, M.Barriga, E.C., A.B., C.C, C.Chaibi, O.Chakrabarty, O'Brien, O.'Brien, S.Capellaro, O 'Brien, T.
Abstract: J. Abadie, B. P. Abbott, R. Abbott, M. Abernathy, T. Accadia, F. Acernese, C. Adams, R. Adhikari, P. Ajith, B. Allen, G. S. Allen, E. Amador Ceron, R. S. Amin, S. B. Anderson, W.G. Anderson, F. Antonucci, M.A. Arain, M. C. Araya, M. Aronsson, Y. Aso, S.M. Aston, P. Astone, D. Atkinson, P. Aufmuth, C. Aulbert, S. Babak, P. Baker, G. Ballardin, T. Ballinger, S. Ballmer, D. Barker, S. Barnum, F. Barone, B. Barr, P. Barriga, L. Barsotti, M. Barsuglia, M.A. Barton, I. Bartos, R. Bassiri, M. Bastarrika, J. Bauchrowitz, Th. S. Bauer, B. Behnke, M.G. Beker, A. Belletoile, M. Benacquista, A. Bertolini, J. Betzwieser, N. Beveridge, P. T. Beyersdorf, I. A. Bilenko, G. Billingsley, J. Birch, S. Birindelli, R. Biswas, M. Bitossi, M.A. Bizouard, E. Black, J. K. Blackburn, L. Blackburn, D. Blair, B. Bland, M. Blom, C. Boccara, O. Bock, T. P. Bodiya, R. Bondarescu, F. Bondu, L. Bonelli, R. Bonnand, R. Bork, M. Born, V. Boschi, S. Bose, L. Bosi, B. Bouhou, M. Boyle, S. Braccini, C. Bradaschia, P. R. Brady, V. B. Braginsky, J. E. Brau, J. Breyer, D.O. Bridges, A. Brillet, M. Brinkmann, V. Brisson, M. Britzger, A. F. Brooks, D. A. Brown, R. Budzynski, T. Bulik, H. J. Bulten, A. Buonanno, J. Burguet–Castell, O. Burmeister, D. Buskulic, C. Buy, R. L. Byer, L. Cadonati, G. Cagnoli, J. Cain, E. Calloni, J. B. Camp, E. Campagna, P. Campsie, J. Cannizzo, K. Cannon, B. Canuel, J. Cao, C. Capano, F. Carbognani, S. Caride, S. Caudill, M. Cavaglia, F. Cavalier, R. Cavalieri, G. Cella, C. Cepeda, E. Cesarini, O. Chaibi, T. Chalermsongsak, E. Chalkley, P. Charlton, E. Chassande-Mottin, S. Chelkowski, Y. Chen, A. Chincarini, N. Christensen, S. S. Y. Chua, C. T.Y. Chung, D. Clark, J. Clark, J. H. Clayton, F. Cleva, E. Coccia, C. N. Colacino, J. Colas, A. Colla, M. Colombini, R. Conte, D. Cook, T. R. Corbitt, N. Cornish, A. Corsi, C. A. Costa, J.-P. Coulon, D.M. Coward, D. C. Coyne, J. D. E. Creighton, T.D. Creighton, A.M. Cruise, R.M. Culter, A. Cumming, L. Cunningham, E. Cuoco, K. Dahl, S. L. Danilishin, R. Dannenberg, S. D’Antonio, K. Danzmann, K. Das, V. Dattilo, B. Daudert, M. Davier, G. Davies, A. Davis, E. J. Daw, R. Day, T. Dayanga, R. De Rosa, D. DeBra, G. Debreczeni, J. Degallaix, M. del Prete, V. Dergachev, R. DeRosa, R. DeSalvo, P. Devanka, S. Dhurandhar, L. Di Fiore, A. Di Lieto, I. Di Palma, M. Di Paolo Emilio, A. Di Virgilio, M. Diaz, A. Dietz, F. Donovan, K. L. Dooley, E. E. Doomes, S. Dorsher, E. S. D. Douglas, M. Drago, R.W. P. Drever, J. C. Driggers, J. Dueck, J.-C. Dumas, S. Dwyer, T. Eberle, M. Edgar, M. Edwards, A. Effler, P. Ehrens, G. Ely, R. Engel, T. Etzel, M. Evans, T. Evans, V. Fafone, S. Fairhurst, Y. Fan, B. F. Farr, D. Fazi, H. Fehrmann, D. Feldbaum, I. Ferrante, F. Fidecaro, L. S. Finn, I. Fiori, R. Flaminio, M. Flanigan, K. Flasch, S. Foley, C. Forrest, E. Forsi, L. A. Forte, N. Fotopoulos, J.-D. Fournier, J. Franc, S. Frasca, F. Frasconi, M. Frede, M. Frei, Z. Frei, A. Freise, R. Frey, T. T. Fricke, D. Friedrich, P. Fritschel, V. V. Frolov, P. Fulda, M. Fyffe, M. Galimberti, L. Gammaitoni, J. A. Garofoli, F. Garufi, M. E. Gaspar, G. Gemme, E. Genin, A. Gennai, I. Gholami, S. Ghosh, J. A. Giaime, S. Giampanis, K. D. Giardina, A. Giazotto, C. Gill, E. Goetz, L.M. Goggin, G. Gonzalez, M. L. Gorodetsky, S. Gosler, R. Gouaty, C. Graef, M. Granata, A. Grant, S. Gras, C. Gray, R. J. S. Greenhalgh, A.M. Gretarsson, C. Greverie, R. Grosso, H. Grote, S. Grunewald, G.M. Guidi, E. K. Gustafson, R. Gustafson, B. Hage, P. Hall, J.M. Hallam, D. Hammer, G. Hammond, J. Hanks, C. Hanna, J. Hanson, J. Harms, G.M. Harry, I.W. Harry, E. D. Harstad, K. Haughian, K. Hayama, J.-F. Hayau, T. Hayler, J. Heefner, H. Heitmann, P. Hello, I. S. Heng, A.W. Heptonstall, M. Hewitson, S. Hild, E. Hirose, D. Hoak, K. A. Hodge, K. Holt, D. J. Hosken, J. Hough, E. J. Howell, D. Hoyland, D. Huet, B. Hughey, S. Husa, S. H. Huttner, T. Huynh–Dinh, D. R. Ingram, R. Inta, T. Isogai, A. Ivanov, P. Jaranowski, W.W. Johnson, D. I. Jones, G. Jones, R. Jones, L. Ju, P. Kalmus, V. Kalogera, S. Kandhasamy, J. B. Kanner, E. Katsavounidis, K. Kawabe, S. Kawamura, F. Kawazoe, W. Kells, D.G. Keppel, A. Khalaidovski, F. Y. Khalili, E. A. Khazanov, H. Kim, P. J. King, D. L. Kinzel, J. S. Kissel, S. Klimenko, V. Kondrashov, R. Kopparapu, S. Koranda, I. Kowalska, D. Kozak, T. Krause, V. Kringel, S. Krishnamurthy, B. Krishnan, A. Krolak, G. Kuehn, J. Kullman, R. Kumar, P. Kwee, M. Landry, M. Lang, B. Lantz, N. Lastzka, A. Lazzarini, P. Leaci, J. Leong, I. Leonor, N. Leroy, N. Letendre, J. Li, T. G. F. Li, N. Liguori, H. Lin, P. E. Lindquist, N. A. Lockerbie, D. Lodhia, M. Lorenzini, V. Loriette, M. Lormand, G. Losurdo, P. Lu, J. Luan, M. Lubinski, A. Lucianetti, H. Luck, A.D. Lundgren, B. Machenschalk, M. MacInnis, M. Mageswaran, K. Mailand, E. Majorana, C. Mak, I. Maksimovic, N. Man, I. Mandel, V. Mandic, M. Mantovani, F. Marchesoni, F. Marion, S. Marka, Z. Marka, E. Maros, J. Marque, F. Martelli, I.W. Martin, R.M. Martin, J. N. Marx, K. Mason, A. Masserot, F. Matichard, L. Matone, R. A. Matzner, N. Mavalvala, R. McCarthy, D. E. McClelland, S. C. McGuire, G. McIntyre, G. McIvor, D. J. A. McKechan, G. Meadors, M. Mehmet, T. Meier, A. Melatos, A. C. Melissinos, G. Mendell, D. F. Menendez, R. A. Mercer, L. Merill, S. Meshkov, C. Messenger, M. S. Meyer, H. Miao, C. Michel, L. Milano, J. Miller, Y. Minenkov, Y. Mino, S. Mitra, V. P. Mitrofanov, G. Mitselmakher, R. Mittleman, B. Moe, M. Mohan, S. D. Mohanty, S. R. P. Mohapatra, D. Moraru, PHYSICAL REVIEW D 85, 089904(E) (2012)
TL;DR: The Superattenuator as mentioned in this paper 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.
Abstract: 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/Hz(1/2) 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.
TL;DR: In this paper, a novel method for the preparation of surface modified polymer films is proposed, by the vaporization of polyhedral oligomeric silsesquioxanes (POSS) and reaction on the polymer surface.
Abstract: In this paper, a novel method for the preparation of surface modified polymer films is proposed, by the vaporization of polyhedral oligomeric silsesquioxanes (POSS) and reaction on the polymer surface. This method was successfully applied to the grafting of an amino-functionalized POSS (POSS-NH2) on poly(styrene-co-maleic anhydride) (PSMA), showing efficient grafting to produce a POSS-rich polymer layer on the vapor-treated surface. The thickness of this layer was found to be controlled by diffusion of POSS, allowing tailoring of the grafted layer thickness with the treatment time. The processing temperature window was found to be defined by the following conditions: (i) high enough to allow significant POSS volatilization, (ii) high enough to allow sufficient polymer chain mobility to react with POSS and (iii) low enough to avoid specimens deformation by polymer flow during the treatment.
TL;DR: Findings suggest that YCC preserves its native structure upon adsorption, dominated by the spectral features associated to the polypeptide chain that tend to overwhelm the heme absorption features.
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TL;DR: Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector as discussed by the authors.
Abstract: Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ET's potential to influence our understanding of fundamental physics, astrophysics and cosmology.
TL;DR: In this paper, a hybrid system based on maleic anhydride-grafted polypropylene (PPgMA) and home-made Ti-containing amino polyhedral oligomeric silsesquioxanes (Ti-POSS-NH 2 ) has been compared with those of systems based on a non-reactive POSS (POSS).
TL;DR: The second science run of the Virgo gravitational wave interferometer took place between July 2009 and January 2010 as discussed by the authors, where the performance of the Interferometer longitudinal control system in terms of duty cycle, stability and control noise was described.
TL;DR: In this paper, a novel nanomaterial which consists of graphene sheets decorated with silsesquioxane molecoles has been developed, which can be used for polymer nanocomposites.
Abstract: A novel nanomaterial which consists of graphene sheets decorated with silsesquioxane molecoles has been developed. Indeed, aminopropyl-silsesquioxane (POSS-NH2) has been employed to functionalize graphene oxide sheets (GOs). The surface grafting of GOs with POSS-NH2 has been established by infrared spectroscopy and X-ray photoelectron spectroscopy, while the morphology has been investigated by field emission electron microscopy as well as by atomic force microscopy. The combination of the amino functionalized POSS molecules with GO sheets produces a hybrid silicon/graphite-based nanomaterial, named GRAPOSS, for which the electrical conductivity of reduced GO was restored, thus allowing promising exploitations in several fields such as polymer nanocomposites.
TL;DR: In this paper, Spectroscopic Ellipsometry (SE) results were obtained on high quality Ta2O5 films deposited on SiO2 substrates by Double Ion Beam Sputtering at the Laboratoire des Materiaux Avances (Lyon, France).
TL;DR: In the presence of abundant open pores, C(18) molecules strongly diffuse within the film interior and bind to the pore walls, whereas in the presenceof porous films with less abundantopen pores, it is observed that the molecules tend to remain confined to the surface region, adopting a SAM-like configuration.
Abstract: This article presents a study of the interaction of octadecanethiol molecules (C18) with nanoporous cluster-assembled gold films under a liquid environment based on a combined spectroscopic ellipsometry and X-ray photoelectron spectroscopy investigation. By comparing the optical response, following the deposition of C18, of cluster-assembled films with varying degrees of porosity with that of flat surfaces and by resolving the corresponding features of the molecule–Au bond, we have been able to define the conditions that either favor molecular in-depth diffusion into the pores or promote the formation of a molecular self-assembled monolayer (SAM) restricted to the film surface. In the presence of abundant open pores, C18 molecules strongly diffuse within the film interior and bind to the pore walls, whereas in the presence of porous films with less abundant open pores we have observed that the molecules tend to remain confined to the surface region, adopting a SAM-like configuration.
TL;DR: A Kalman filter is developed, based on the obtained state space representation, that estimates from open loop time domain data, the state variables of the Virgo gravitational wave interferometer system.
Abstract: We report an application of Kalman filtering to the inverted pendulum (IP) of the Virgo gravitational wave interferometer. Using subspace method system identification techniques, we calculated a linear mechanical model of Virgo IP from experimental transfer functions. We then developed a Kalman filter, based on the obtained state space representation, that estimates from open loop time domain data, the state variables of the system. This allows the observation (and eventually control) of every resonance mode of the IP mechanical structure independently.
TL;DR: The Virgo interferometer for gravitational wave detection is described in this article, with the aim of increasing the sensitivity, mainly through the introduction of fused silica wires to suspend mirrors and by increasing the Finesse of the Fabry-Perot cavities.
Abstract: The Virgo interferometer for gravitational wave detection is described. During the commissioning phase that followed the first scientific data taking run an unprecedented sensitivity was obtained in the range 10-60 Hz. Since then an upgrade program has begun, with the aim of increasing the sensitivity, mainly through the introduction of fused silica wires to suspend mirrors and by increasing the Finesse of the Fabry-Perot cavities. Plans until the shutdown for the construction of the Advanced Virgo detector are given as well as the status of the upgrade.
University of Glasgow1, University of Salerno2, Spanish National Research Council3, Albert Einstein Institution4, University of Southampton5, Université Paris-Saclay6, PSL Research University7, Washington State University8, University of Warsaw9, University of Naples Federico II10, University of Birmingham11, Cardiff University12, University of Rome Tor Vergata13, Moscow State University14, Leibniz University of Hanover15, California Institute of Technology16, VU University Amsterdam17, fondazione bruno kessler18, University of Cambridge19, University of Tübingen20, University of Urbino21, University of Jena22, University of Florence23, Massachusetts Institute of Technology24, University of Minnesota25, University of Savoy26, Pennsylvania State University27, University of Pisa28, Roma Tre University29, Sapienza University of Rome30, University of Mississippi31, University of the Balearic Islands32
TL;DR: The advanced interferometer network will herald a new era in observational astronomy as mentioned in this paper, and there is a very strong science case to go beyond the advanced detector network and build detectors that operate in a frequency range from 1 Hz to 10 kHz, with sensitivity a factor 10 better in amplitude.
Abstract: The advanced interferometer network will herald a new era in observational astronomy. There is a very strong science case to go beyond the advanced detector network and build detectors that operate in a frequency range from
1 Hz to 10 kHz, with sensitivity a factor 10 better in amplitude. Such detectors will be able to probe a range of topics in nuclear physics, astronomy, cosmology
and fundamental physics, providing insights into many unsolved problems in these areas.
TL;DR: In this paper, a comparison between spectroscopic ellipsometry (SE) spectra obtained from yeast cytochrome c (YCC) adsorption on flat and cluster-assembled nanostructured gold films, obtained by supersonic cluster beam deposition is proposed.
Abstract: Spectroscopic ellipsometry (SE) has been used to investigate the adsorption of yeast cytochrome c (YCC) on gold films. YCC is a prototypical molecular system to evaluate the sensitivity and reliability of optical methods in probing conformational changes upon adsorption at surfaces. Measurements have been performed in situ in aqueous solutions at room temperature. We have applied to monolayer-thick YCC films the same scheme of analysis of SE spectra used in our recent works on thiolate self-assembled monolayers on gold, exploiting the so-called δΨ and δΔ difference spectra. A comparison between δΨ and δΔ spectra obtained from YCC adsorption on flat and cluster-assembled nanostructured gold films, obtained by supersonic cluster beam deposition is proposed. For both kinds of substrate δΨ and δΔ, difference spectra show well-defined features related to molecular optical absorptions typical of the so-called heme group, in particular the Soret band at about 410 nm. These features appear in the same position found for molecules in solution, suggesting that YCC native conformation is maintained upon adsorption also in the case of a substrate with typical roughness at the nanoscale.
TL;DR: In this article, the performance of the Automatic Alignment sensing and control system in the Virgo gravitational wave detector, during the second scientific run from July 7th 2009 to January 8th 2010, is described.
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TL;DR: In this article, an attempt is made to measure the attenuation of emitted noise at the ITF and correlate it to the distance from the source and to seismic attenuation models in soil.
Abstract: The Virgo gravitational wave detector is an interferometer (ITF) with 3km arms located in Pisa, Italy. From July to October 2010, Virgo performed its third science run (VSR3) in coincidence with the LIGO detectors. Despite several techniques adopted to isolate the interferometer from the environment, seismic noise remains an important issue for Virgo. Vibrations produced by the detector infrastructure (such as air conditioning units, water chillers/heaters, pumps) are found to affect Virgo's sensitivity, with the main coupling mechanisms being through beam jitter and scattered light processes. The Advanced Virgo (AdV) design seeks to reduce ITF couplings to environmental noise by having most vibration-sensitive components suspended and in-vacuum, as well as muffle and relocate loud machines. During the months of June and July 2010, a Guralp-3TD seismometer was stationed at various locations around the Virgo site hosting major infrastructure machines. Seismic data were examined using spectral and coherence analysis with seismic probes close to the detector. The primary aim of this study was to identify noisy machines which seismically affect the ITF environment and thus require mitigation attention. Analyzed machines are located at various distances from the experimental halls, ranging from 10m to 100m. An attempt is made to measure the attenuation of emitted noise at the ITF and correlate it to the distance from the source and to seismic attenuation models in soil.
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TL;DR: In this paper, the authors presented 90% confidence level (CL) upper-limit maps of GW strain power with typical values between 2-20x10^-50 strain and 5-35x10−49 strain for pointlike and extended sources respectively.
Abstract: The gravitational-wave (GW) sky may include nearby pointlike sources as well as astrophysical and cosmological stochastic backgrounds. Since the relative strength and angular distribution of the many possible sources of GWs are not well constrained, searches for GW signals must be performed in a model-independent way. To that end we perform two directional searches for persistent GWs using data from the LIGO S5 science run: one optimized for pointlike sources and one for arbitrary extended sources. The latter result is the first of its kind. Finding no evidence to support the detection of GWs, we present 90% confidence level (CL) upper-limit maps of GW strain power with typical values between 2-20x10^-50 strain^2 Hz^-1 and 5-35x10^-49 strain^2 Hz^-1 sr^-1 for pointlike and extended sources respectively. The limits on pointlike sources constitute a factor of 30 improvement over the previous best limits. We also set 90% CL limits on the narrow-band root-mean-square GW strain from interesting targets including Sco X-1, SN1987A and the Galactic Center as low as ~7x10^-25 in the most sensitive frequency range near 160 Hz. These limits are the most constraining to date and constitute a factor of 5 improvement over the previous best limits.