In Sardinia, scientific measurements are proceeding for the characterization of the site of the Sos Enattos mines, in Lula, for the construction of the third generation Einstein Telescope gravitational wave observatory.
Today, 20 January 2020, in Sardinia, the installation of the first large-scale seismic sensor network will begin for an extensive campaign of geophysical measurements near the Sos Enattos metal mine, in Lula, the candidate site from Italy to host the Einstein Telescope (ET), the third generation gravitational wave observatory, a highly sensitive instrument that will make a decisive contribution to improving our knowledge of the universe and the physical processes that govern it. Thanks to the fundamental contribution of the Autonomous Region of Sardinia, the site, managed by the IGEA, today hosts the SarGrav Laboratory which acts as a support infrastructure for all the characterization activities in progress.
The National Institute of Nuclear Physics (INFN), the National Institute of Geophysics and Volcanology (INGV), the National Institute of Astrophysics (INAF) and the Universities of Sassari and Cagliari participate in the ET scientific collaboration.
In detail, today the researchers of the Pisa section of the INGV will install 15 seismometric stations near the Sos Enattos mine, to measure the ground vibrations which constitute the seismic background noise. Using techniques borrowed from the analysis of radar signals, the data recorded by these stations will make it possible to identify the main sources of seismic noise, both natural and artificial, and to follow their evolution over time. The operation, which will last two weeks, is managed not only by INGV, but also by researchers from the Cagliari section of the National Institute of Nuclear Physics, the University of Cagliari, Sassari and the Sapienza University of Rome, with the support of the IGEA SpA
At the same time, other researchers from the INGV Sections of Rome and the Etneo Observatory of Catania, with the geologists of the University of Sassari, will carry out the first inspections necessary for the execution of a seismic tomography, i.e. an image of the subsoil obtained from the registration of seismic waves generated artificially by a vibrating mass driven by a special heavy vehicle. The data will also be used to study the Newtonian noise of the site in which a research group from the Physics department of the University of Cagliari is also involved.
The purpose of these two campaigns is twofold: to further quantify the exceptional seismic 'silence' of the area, a fundamental requirement for the operation of ET, and to reconstruct the area which, hopefully, will host ET. The results of these subsoil geology measurements, in view of the design of the candidate site tunnel system (the other is located on the border between Belgium, Germany and Holland, will constitute one of the evaluation elements for the final choice between the two
in the Limburg region).
The Einstein Telescope is the new generation interferometric observatory designed to capture and measure the passage of gravitational waves generated by the collisions of black holes and neutron stars that occurred at distances of millions (billions) of light years from us. The faint signals come from the farthest reaches of the cosmos and travel throughout the universe. In order to capture and study them, it is necessary to build technological infrastructures in silent and isolated places, sheltered from geophysical (low seismicity) and anthropic noises that can invalidate the measurements. Due to its characteristics, the Lula-Bitti-Onanì site is one of the ideal candidates in Europe for the construction of the work. Competition from the site on the border between Holland, Belgium and Germany is high.
The Einstein Telescope project is considered by the European scientific community to be a strategic project and is supported by several countries including Italy which in September 2020, through the Ministry of University and Research, nominated it for the next ESFRI European Roadmap 2021 Strategy Forum on Research Infrastructure, the European strategic forum that identifies which will be the future major research infrastructures in which to invest at European level.
The measurements of the seismographs installed in Lula and subsequent research will help strengthen the candidacy of the Sardinian site in Europe, bringing the island to the top of research in the field of physics.