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EINSTEIN TELESCOPE

The Einstein Telescope (ET) is the large research infrastructure that will host the future gravitational wave detector to be built in Europe, a project with global scientific and technological impact. Italy is a candidate to host it in Sardinia in the area of the disused Sos Enattos mine.
ET is considered a leading project at an international level, so much so that it is included in the Roadmap of ESFRI 2021 (European Strategy Forum on Research Infrastructures), the European body that indicates which scientific infrastructures are crucial to invest in in Europe, thanks to a proposal Italian guide, supported by Belgium, the Netherlands, Poland and Spain.
The Ministry of Universities and Research (MUR) established a high-profile Technical and Scientific Committee in order to support at best the Italian candidacy by decree of Minister Anna Maria Bernini. The committee is chaired by the Physics Nobel Laureate Giorgio Parisi.

DEPLIANT ET ITALY

LA SCIENZA DI ET

UN VIAGGIO INDIETRO NEL TEMPO

INTEFEROMETRI A CONFRONTO

Scientific objectives

The Einstein Telescope is a fundamental research project and, therefore, its primary and overriding mission is scientific. Its goal is to study the universe with gravitational waves, through its history, tracing it back to the time when light appeared, to understand its origin, how it formed and evolved and what its future will be. The ET will enable the detection of expected but yet unobserved phenomena such as continuous emission from neutron stars, supernova explosions, as well as the measurement of the cosmological or astrophysical background of gravitational waves. It will thus be possible, for instance, to study the ways in which black holes form, their characteristics, and their evolution. The detection of many gravitational signals from neutron stars, in addition, will provide a true nuclear physics laboratory, with characteristics not achievable on Earth, in which the behavior of matter under extreme conditions can be studied. Detecting a large number of these events will, moreover, allow to do population studies of black holes and neutron stars and, thus, to carry out veritable demographic analyses of the universe.

Einstein Telescope Italy, logo of the Italian candidacy and schematization of the two possible configurations (© INFN)

Overview of the SOS Enattos mine (© EGO/INFN)

The infrastructure and the Italian site of SOS Enattos

The ET project involves the construction of a large underground facility that will house a gravitational wave detector between 100 and 300 metres deep to keep it in “silent” conditions, isolating it from the vibrations produced by both seismic waves and human activities, which constitute what is called “noise”, a source of disturbance for the measurements to be made by the ET. Two possible configurations of the detector are currently being examined by the scientific community: one with a delta shape ((Δ)), with ten kilometer long arms, which involves the creation of a single instrument, and the other with an L shape (L), as the current gravitational interferometers, with arms fifteen kilometers long, which involves the creation of two instruments ata certain distance one from the other. There are two competing sites: the Italian site in the area of the former Sos Enattos metal mine, in the Nuoro area, in the north-east of Sardinia, and the Dutch site in an area of the Meuse-Rhine Euroregion, on the border between countries Netherlands, Belgium and Germany. Inland Sardinia is an ideal place to host Einstein Telescope.

There are many geological reasons why the Sos Enattos area is an ideal place for the ET activities. Seismic noise, which affects detector performance at low frequencies, is very low due to the geological characteristics of Sardinia. Sardinia is, in fact, a microplate, i.e., a detached portion of the Eurasian plate that is not connected to the most active tectonic zones. Thus, the region is not affected by crustal deformation phenomena or seismicity and volcanoes. In fact, it is a stable and solid area, characterized by rock masses that are ideal for safely building the underground spaces that will constitute the ET laboratory. Moreover, the limited presence of groundwater in the area reduces the possibility of seepage or seismic and Newtonian noise. Finally, in the area around Nuoro, between the municipalities of Bitti, Lula and Onanì, there are large expanses of rural areas with very low population density and, therefore, limited anthropogenic and industrial activity. All this makes the Sos Enattos site the ‘silent’ environment that ET needs, to operate protected and insulated from the ‘noise’ that would compromise its measurements.

Nobel science and technology

Einstein Telescope will be a gravitational wave detector based on the successes of the laser interferometry technique, used in the second generation LIGO and Virgo experiments and it will be able to observe a volume of the universe at least a thousand times greater than the interferometers active today. In fact, its sensitivity will be significantly enhanced compared to current experiments, thanks to the increase in the size of the detector, and the implementation of new and innovative technologies.

The idea of the ET project builds on the success of the current LIGO and Virgo detectors, the observations of which -since 2015 (the year gravitational waves were discovered) to the present day – have revolutionised the way one studies the universe. These detectors opened the era of gravitational astronomy (the study of celestial bodies and the cosmos through gravitational waves) as well as multimessenger astronomy (the study of the same astrophysical phenomenon through information from multiple cosmic messengers): gravitational waves, electromagnetic radiation, and neutrinos. Discoveries concerning gravitational waves, in which Italy has been a leader thanks to the Virgo experiment, located at the European Gravitational Observatory near Pisa, have made this area of fundamental research one of the most promising.

The scientific collaboration

The ET community, which has been active for more than 15 years, has been organised into an international scientific collaboration since 2022. Such collaboration consists of more than 1,400 experts, researchers, engineers, technicians, and data scientists, belonging to more than 220 institutions spread across 23 nations, both in Europe (Czech Republic, France, Germany, Greece, Hungary, Switzerland, and United Kingdom), and worldwide.

For more information, visit the project website