Gravitational waves: listening to the whispers of the Universe
In February 2016, for the first time Gravitational Waves detection has been announced by the LIGO-Virgo collaboration. In the following years, during the first and second Observing Runs of the Advanced Gravitational-Wave detectors, 11 signals in total were observed. Due to their week amplitude, Gravitational Waves are expected to produce a very small effect on free-falling masses, which undergo a displacement of the order of 10^(-18) m. For the time being, interferometric detectors are the most sensitive instruments to measure such relative distance change, which is translated into phase variation of the laser field. Detecting such a feeble effect is a tough challenge against the noise sources, which overcome by several orders of magnitude the strength of the Gravitational Wave effect. In this Colloquium, I will talk you through the complexity of the experimental work underling the tuning of this instrument. Starting from the working principle of the detector, we will go through the fundamental noise sources which limit the interferometer sensitivity, the challenges of installation, commissioning, tuning and calibration faced by Virgo, a 3 kilometer-long arms interferometer situated near Pisa, until the achievement of the sensitivity milestone, which allowed the Virgo detector to start the third joint Observation run together with the two Advanced LIGO interferometers.
Friday, 24 May 2019, ore 14:30 — Sala Wataghin