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International Research Experiences for Undergraduates

Department of Physics

EGO – Virgo site, Cascina, Italy

The Virgo interferometer is the most sensitive gravitational-waves (GW) detector in Europe.  In the early 2000s, initial Virgo was realized in a partnership between France and Italy.  The system is now under an intense upgrade program, supported by the CNRS (France), INFN (Italy) and  NIKHEF (Netherlands). The new detector Advanced VIRGO will use improved mirrors, a higher power laser, and signal recycling techniques in order to allow, together with the two LIGO interfermometers in USA, the first direct detection of GW signals. In Summer 2016 Advanced Virgo will complete the commissioning phase in readiness for its first science run.

 Proposed Projects

  • Predicting terrestrial gravity noise in the Virgo detector based on new data from site characterization:
    The Virgo collaboration is intensifying efforts to improve our understanding of terrestrial gravity noise in the Virgo detector. This requires a detailed model of how this noise is produced at the Virgo site. For this project, the student will analyze data acquired at the site by a network of seismometers with specific focus on the estimation of correlation functions and their role in the modelling of terrestrial gravity noise. Furthermore, the student will implement details of the structure of the laboratory buildings and near-surface geology to construct an accurate noise model. The noise model will not only allow us to predict the spectrum of terrestrial gravity noise in the Virgo detector and associated sensitivity limitations, but it will also make it possible to define some of the design criteria of the noise-mitigation system to be developed in the coming years.
    Mentor: Irene Fiori

 

  • Validation and optimization of an earthquake early warning for Virgo:
    EQ shakes excite mirror suspensions and can cause GW interferometeric detectors to lose the resonant condition (we say it goes out of lock). Recovering from EQ shakes means damping mirror suspensions and realign mirror test masses. This operation can take up to hours effectively reducing the duty cycle for GW observations. Knowing with some few tens of second the arrival time of EQ waves at the site the interferometer can be put in a “safe” condition (i.e. switching to a more robust, although bit noisier, feedback control for the suspensions) so to keep it in operation. Virgo is setting up an EQ monitoring and prediction system. The core of the code for the EQ prediction is the one developed for LIGO, and it is named Seismon. The Seismon code fetches EQ events information with few minutes latency from the USGS seismometric network. Then it predicts the arrival time and amplitude of surface R waves at a site. The Seismon code needs to be validated and optimized for Virgo. Past and recent EQ data collected by seismometers at the site can be used for this purpose, in particular for improving the R-wave amplitude prediction at the site. Information from the Italian seismological network should be available and integrated in with the code in order to have a better coverage for EQ occurring within Italy. Eventually the correlation between EQ shakes at the site and ITF losses of lock can be studied.
    Mentor: Irene Fiori (with the contribution of G.Cella, J.Harms)

 

  • Characterization studies of the noise environment of the Advanced Virgo interferometer:
    Among commissioning activities is the identification and mitigation of sources of environmental noise disturbing the interferometer operation, or even jeopardizing the detector sensitivity. The student will take part in this activity, which consists in both data analysis and experimental work.  In part, the student will refine algorithms to correlate interferometer signals with auxiliary signals (magnetic, seismic, acoustic probes or signals monitoring infrastructure machines) to identify the source. Additionally, she/he will devise and execute experimental tests which inject artificial disturbances to measure the coupling of the noise to the interferometer.
    The candidate is advised to have: skills and motivation in experimental physics, a basic level knowledge of signal processing, some practice with MATLAB software and programming.
    Mentor: Irene Fiori

Related Project 2008: “Environmental Noise in the Virgo Interferometer”
Related Project 2009: “Noise-hunting during the VSR2 run at Virgo”
Related Project 2010: “Characterization of the Virgo Seismic Environment”
Related Project 2011: “Environmental Noise of VSR4 and Preparing for Advanced Virgo”
Related Project 2013: “Characterization of Magnetic Glitches in VSR4 data using correlations between Omicron triggers”
Related Project 2014: “Studying the Behavior of the West End Tower with Magnetic Injections”
Related Project 2015: “A New Dead Channel Monitor in the Virgo Detector Monitoring System”
Related Project 2015: “PROSPECTOR: An Automated Systematic Tool for Noise Hunting”