Speaker
Description
Environmental noise can affect the performance of ground-based gravitational-wave interferometric detectors, such as Virgo, through magnetic and vibro-acoustic coupling mechanisms, impacting both the detector sensitivity and the surrounding experimental areas hosting sensitive equipment.
In this work, we present measurements of magnetic coupling functions at low frequency (below 25 Hz) at the Virgo interferometer, performed across the three main experimental buildings. Controlled magnetic injections are used to estimate frequency-dependent coupling functions and to compare low-frequency measurements with swept-sine injections carried out during O4b and O4c observing runs. The observed frequency dependence of the coupling functions is investigated in order to identify the underlying coupling paths (e.g. mirror payload stage). This activity represents a first step toward the development of a magnetic coupling model consistent with experimental data.
In parallel, we have started setting up a simulation of the acoustic field in the Virgo Injection and Detection laboratories - hosting the detector's input and output optics, respectively - using the ANSYS simulation package, with the goal of investigating how sound propagates and interacts with sensitive components.
Preliminary projections indicate that the present level of acoustic noise in the Injection Laboratory is close to the Virgo detector sensitivity in specific frequency regions, suggesting a contribution from coupling mechanisms such as jitter noise.
This activity can provide a complementary simulation framework to assess acoustic conditions in future configurations of these laboratories, including the planned expansion for the implementation of the Virgo detector upgrade with stable optical cavities.
The overall goal of this work is to develop experimentally validated models to understand environmental noise coupling mechanisms and support mitigation strategies, with particular relevance for the design and sensitivity targets of future detectors such as the Einstein Telescope.