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Dive into the research topics where F. Gibert is active.

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Featured researches published by F. Gibert.


Classical and Quantum Gravity | 2011

The LISA Pathfinder DMU and Radiation Monitor

Priscilla Canizares; M. Chmeissani; Aleix Conchillo; M Diaz–Aguiló; Enrique García-Berro; L Gesa; F. Gibert; C. Grimani; I. Lloro; Alberto Lobo; I. Mateos; M. Nofrarias; J. Ramos-Castro; J. Sanjuan; Carlos F. Sopuerta; H.M. Araújo; P. Wass

The LISA Pathfinder DMU (Data Management Unit) flight model was formally accepted by ESA and ASD on 11 February 2010, after all hardware and software tests had been successfully completed. The diagnostics items are scheduled to be delivered by the end of 2010. In this paper, we review the requirements and performance of this instrumentation, specially focusing on the Radiation Monitor and the DMU, as well as the status of their programmed use during mission operations, on which work is ongoing at the time of writing.


Physical Review D | 2014

Data series subtraction with unknown and unmodeled background noise

S. Vitale; Giuseppe Congedo; R. Dolesi; V. Ferroni; M. Hueller; D. Vetrugno; W. J. Weber; H. Audley; Karsten Danzmann; I. Diepholz; M. Hewitson; N. Korsakova; L. Ferraioli; F. Gibert; Nikolaos Karnesis; M. Nofrarias; H. Inchauspé; E. Plagnol; Oliver Jennrich; Paul McNamara; M. Armano; James Ira Thorpe; P. Wass

LISA Pathfinder (LPF), the precursor mission to a gravitational wave observatory of the European Space Agency, will measure the degree to which two test masses can be put into free fall, aiming to demonstrate a suppression of disturbance forces corresponding to a residual relative acceleration with a power spectral density (PSD) below (30 fm/sq s/Hz)(sup 2) around 1 mHz. In LPF data analysis, the disturbance forces are obtained as the difference between the acceleration data and a linear combination of other measured data series. In many circumstances, the coefficients for this linear combination are obtained by fitting these data series to the acceleration, and the disturbance forces appear then as the data series of the residuals of the fit. Thus the background noise or, more precisely, its PSD, whose knowledge is needed to build up the likelihood function in ordinary maximum likelihood fitting, is here unknown, and its estimate constitutes instead one of the goals of the fit. In this paper we present a fitting method that does not require the knowledge of the PSD of the background noise. The method is based on the analytical marginalization of the posterior parameter probability density with respect to the background noise PSD, and returns an estimate both for the fitting parameters and for the PSD. We show that both these estimates are unbiased, and that, when using averaged Welchs periodograms for the residuals, the estimate of the PSD is consistent, as its error tends to zero with the inverse square root of the number of averaged periodograms. Additionally, we find that the method is equivalent to some implementations of iteratively reweighted least-squares fitting. We have tested the method both on simulated data of known PSD and on data from several experiments performed with the LISA Pathfinder end-to-end mission simulator.


Physical Review D | 2014

Bayesian model selection for LISA pathfinder

Nikolaos Karnesis; M. Nofrarias; Carlos F. Sopuerta; F. Gibert; M. Armano; H. Audley; Giuseppe Congedo; I. Diepholz; L. Ferraioli; M. Hewitson; M. Hueller; N. Korsakova; Paul McNamara; E. Plagnol; S. Vitale

The main goal of the LISA Pathfinder (LPF) mission is to fully characterize the acceleration noise models and to test key technologies for future space-based gravitational-wave observatories similar to the eLISA concept. The data analysis team has developed complex three-dimensional models of the LISA Technology Package (LTP) experiment onboard the LPF. These models are used for simulations, but, more importantly, they will be used for parameter estimation purposes during flight operations. One of the tasks of the data analysis team is to identify the physical effects that contribute significantly to the properties of the instrument noise. A way of approaching this problem is to recover the essential parameters of a LTP model fitting the data. Thus, we want to define the simplest model that efficiently explains the observations. To do so, adopting a Bayesian framework, one has to estimate the so-called Bayes factor between two competing models. In our analysis, we use three main different methods to estimate it: the reversible jump Markov chain Monte Carlo method, the Schwarz criterion, and the Laplace approximation. They are applied to simulated LPF experiments in which the most probable LTP model that explains the observations is recovered. The same type of analysis presented in this paper is expected to be followed during flight operations. Moreover, the correlation of the output of the aforementioned methods with the design of the experiment is explored.


Journal of Physics: Conference Series | 2015

Disentangling the magnetic force noise contribution in LISA Pathfinder

M. Armano; H. Audley; G. Auger; J. Baird; P. Binetruy; M. Born; D. Bortoluzzi; N. Brandt; A. Bursi; M. Caleno; A. Cavalleri; A. Cesarini; M. Cruise; Karsten Danzmann; I. Diepholz; R. Dolesi; N. Dunbar; L. Ferraioli; V. Ferroni; E. Fitzsimons; M. Freschi; J. Gallegos; C. García Marirrodriga; R. Gerndt; L. Gesa; F. Gibert; Domenico Giardini; R. Giusteri; C. Grimani; I. Harrison

Magnetically-induced forces on the inertial masses on-board LISA Pathfinder are expected to be one of the dominant contributions to the mission noise budget, accounting for up to 40%. The origin of this disturbance is the coupling of the residual magnetization and susceptibility of the test masses with the environmental magnetic field. In order to fully understand this important part of the noise model, a set of coils and magnetometers are integrated as a part of the diagnostics subsystem. During operations a sequence of magnetic excitations will be applied to precisely determine the coupling of the magnetic environment to the test mass displacement using the on-board magnetometers. Since no direct measurement of the magnetic field in the test mass position will be available, an extrapolation of the magnetic measurements to the test mass position will be carried out as a part of the data analysis activities. In this paper we show the first results on the magnetic experiments during an end- to-end LISA Pathfinder simulation, and we describe the methods under development to map the magnetic field on-board.


Physical Review D | 2013

Subtraction of temperature induced phase noise in the LISA frequency band

M. Nofrarias; F. Gibert; Nikolaos Karnesis; A. F. Garcia; M. Hewitson; Gerhard Heinzel; Karsten Danzmann

Temperature fluctuations are expected to be one of the limiting factors for gravitational wave detectors in the very low frequency range. Here we report the characterisation of this noise source in the LISA Pathfinder optical bench and propose a method to remove its contribution from the data. Our results show that temperature fluctuations are indeed limiting our measurement below one millihertz, and that their subtraction leads to a factor 5.6 (15 dB) reduction in the noise level at the lower end of the LISA measurement band 10^{-4} Hz, which increases to 20.2 (26 dB) at even lower frequencies, i.e., 1.5x10^{-5} Hz. The method presented here can be applied to the subtraction of other noise sources in gravitational wave detectors in the general situation where multiple sensors are used to characterise the noise source.


Journal of Physics: Conference Series | 2012

Temperature coefficient improvement for low noise magnetic measurements in LISA

I. Mateos; M Diaz-Aguiló; F. Gibert; I. Lloro; Alberto Lobo; M. Nofrarias; J. Ramos-Castro

Previous research with Anisotropic Magnetoresistive sensors (AMR) have shown significant improvements for weak magnetic field applications using dedicated noise reduction techniques in the signal conditioning circuit. However, an important source of error that must be addressed is the thermal dependence of the sensor system, more significant in the AMR sensitivity. The external temperature fluctuations affect the output of the sensors due to the temperature coefficient of the magnetoresistors, which may cause an increase of the estimation of the noise spectral density at low frequencies. Ongoing research using a low noise/low temperature coefficient current source to supply the sensors bridge enhances the thermal performance of the sensors at the lower end of the LISA bandwidth. Preliminary results are shown in this paper.


Journal of Physics: Conference Series | 2015

In-flight thermal experiments for LISA Pathfinder: Simulating temperature noise at the Inertial Sensors

F. Gibert; M. Nofrarias; M. Armano; H. Audley; G. Auger; J. Baird; P. Binetruy; M. Born; D. Bortoluzzi; N. Brandt; A. Bursi; M. Caleno; A. Cavalleri; A. Cesarini; M. Cruise; Karsten Danzmann; I. Diepholz; R. Dolesi; N. Dunbar; L. Ferraioli; V. Ferroni; E. Fitzsimons; M. Freschi; J. Gallegos; C. García Marirrodriga; R. Gerndt; L Gesa; Domenico Giardini; R. Giusteri; C. Grimani

Thermal Diagnostics experiments to be carried out on board LISA Pathfinder (LPF) will yield a detailed characterisation of how temperature fluctuations affect the LTP (LISA Technology Package) instrument performance, a crucial information for future space based gravitational wave detectors as the proposed eLISA. Amongst them, the study of temperature gradient fluctuations around the test masses of the Inertial Sensors will provide as well information regarding the contribution of the Brownian noise, which is expected to limit the LTP sensitivity at frequencies close to 1 mHz during some LTP experiments. In this paper we report on how these kind of Thermal Diagnostics experiments were simulated in the last LPF Simulation Campaign (November, 2013) involving all the LPF Data Analysis team and using an end-to-end simulator of the whole spacecraft. Such simulation campaign was conducted under the framework of the preparation for LPF operations.


arXiv: General Relativity and Quantum Cosmology | 2012

State-space modelling for heater induced thermal effects on LISA Pathfinder's Test Masses

F. Gibert; M. Nofrarias; M. Diaz-Aguilo; Alberto Lobo; Nikolaos Karnesis; Ignacio Mateos; J. Sanjuan; I. Lloro; L. Gesa; Víctor Martín

The OSE (Offline Simulations Environment) simulator of the LPF (LISA Pathfinder) mission is intended to simulate the different experiments to be carried out in flight. Amongst these, the thermal diagnostics experiments are intended to relate thermal disturbances and interferometer readouts, thereby allowing the subtraction of thermally induced interferences from the interferometer channels. In this paper we report on the modelling of these simulated experiments, including the parametrisation of different thermal effects (radiation pressure effect, radiometer effect) that will appear in the Inertial Sensor environment of the LTP (LISA Technology Package). We report as well how these experiments are going to be implemented in the LTPDA toolbox, which is a dedicated tool for LPF data analysis that will allow full traceability and reproducibility of the analysis thanks to complete recording of the processes.


Journal of Physics: Conference Series | 2012

LISA PathFinder radiation monitor proton irradiation test results

I. Mateos; M. Diaz-Aguilo; F. Gibert; C. Grimani; D. Hollington; I. Lloro; Alberto Lobo; M. Nofrarias; J. Ramos-Castro

The design of the Radiation Monitor in the LISA Technology Package on board LISA Pathnder is based on two silicon PIN diodes, placed parallel to each other in a telescopic configuration. One of them is able to record spectral information of the particle hitting the diode. A test campaign for the flight model Radiation Monitor was done in the Paul Scherrer Institute Proton Irradiation Facility in September 2010. Its purpose was to check correct functionality of the Radiation Monitor under real high energy proton fluxes. Here we present the results of the experiments done and their assessment by means of a simulated flight model geometry using GEANT4 toolkit. No deviation from nominal RM performance was detected, which means the instrument is fully ready for flight.


Journal of Physics: Conference Series | 2011

Milli-Hertz Gravitational Waves: LISA and LISA PathFinder

H.M. Araújo; Priscilla Canizares; M. Chmeissani; A. Conchillo; M. Diaz-Aguilo; Enrique García-Berro; L. Gesa; F. Gibert; C. Grimani; W Hajdas; D. Hollington; I. Lloro; Alberto Lobo; I. Mateos; M. Nofrarias; C. Puigdengoles; J. Ramos-Castro; J. Sanjuan; Carlos F. Sopuerta; P. Wass

Ground based GW detectors are limited at their lower frequency band (1-10 Hz) by settlement gravity gradients and seismic noise, and their sensitivity peaks at around 100 Hz. Sources in this band are mostly short duration signals, and their rates uncertain. Going down to milli-Hertz frequencies significantly increases the number and types of available sources. LISA was planned with the idea to explore a likely richer region of the GW spectrum, beyond that accessible to ground detectors; the latter are however expected to produce the first GW observations. In this paper I will present the main LISA concepts; in particular, emphasis will be placed on LISAPathFinder, the ESA precursor of LISA, in which our research group in Barcelona is heavily involved.

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M. Armano

European Space Agency

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M. Nofrarias

Institut de Ciències de l'Espai

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C. Grimani

Istituto Nazionale di Fisica Nucleare

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