In this work we report the ongoing characterization of the Sos Enattos former mine (Sardinia, Italy), one of the two candidate sites for the Einstein Telescope (ET), the European third-generation ...underground interferometric detector of Gravitational Waves. The Sos Enattos site lies on a crystalline basement, made of rocks with good geomechanical properties, characterized by negligible groundwater. In addition, the site has a very low seismic background noise due to the absence of active tectonics involving Sardinia. Finally, the area has a low population density, resulting in a reduced anthropic noise even at the ground level. This location was already studied in 2012-2014 as a promising site for an underground detector. More recently, in March 2019, we deployed a new network of surface and underground seismometers at the site, that is currently monitoring the local seismic noise. Most of the energy carried by the seismic waves is due to the microseisms below 1 Hz, showing a significant correlation with the waves of the west Mediterranean sea. Above 1 Hz the seismic noise in the underground levels of the mine approaches the Peterson's low noise model. Exploiting mine blasting works into the former mine, we were also able to perform active seismic measurements to evaluate the seismic waves propagation across the area. In conclusion we also give a first assessment about the acoustic and magnetic noise in this underground site.
The Advanced Virgo monolithic fused silica suspension Aisa, D.; Aisa, S.; Campeggi, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
824
Journal Article
Recenzirano
The detection of gravitational waves is one of the most challenging prospects faced by experimental physicists. Suspension thermal noise is an important noise source at operating frequencies between ...approximately 10 and 30Hz, and represents a limit to the sensitivity of the ground based interferometric gravitational wave detectors. Its effects can be reduced by minimizing the losses and by optimizing the geometry of the suspension fiber as well as its attachment system. In this proceeding we will describe the mirrors double stage monolithic suspension system to be used in the Advanced Virgo (AdV) detector. We also present the results of the thermal noise study, performed with the help of a finite elements model, taking into account the precise geometry of the fibers attachment systems on the suspension elements. We shall demonstrate the suitability of this suspension for installation in AdV.
•Suspension system design for the test masses of the gravitational wave detectors.•Finite element model studies.•Suspension thermal noise studies.
In this paper, we report a study of the seismic noise measured in the underground Baksan neutrino observatory in the framework of the site qualification for third generation Gravitational Wave ...detectors like the Einstein Telescope (Einstein gravitational wave telescope conceptual design study, ET-0106C-10.
http://et-gw.eu/etdsdocument
, 2011) and Cosmic Explorer (
https://cosmicexplorer.org/
). The main spectral feature below 1
Hz
is the oceanic microseism, while for greater frequencies the measured horizontal and vertical accelerations approach the Peterson low noise model. Using two synchronized seismometers, we also studied the coherence in the microseismic band (0.1–0.5Hz) between three underground stations located at 0.3 km, 1.4 km and 3.7 km from the tunnel entrance. Finally, on the base of our measurements, we evaluate the Newtonian noise contribution from the seismic noise background of body waves.
► Cryogenics is one of key technologies of a third generation of interferometric gravitational wave detectors as in LCGT and ET projects. ► The results reported in this paper are the basis towards ...the realization of a full cryogenic interferometer. ► The behavior of a suspension prototype is studied both for optimizing the heat extraction from the mirror and the mirror control.
Thermal noise is a limiting factor of interferometric gravitational wave detectors sensitivity in the low and intermediate frequency range. A concrete possibility for beating this limit, is represented by the development of a cryogenic last stage suspension to be integrated within a complex seismic isolation system. To this purpose a last stage payload prototype has been designed and built. It has been suspended within a dedicated cryostat with the same technique adopted for the VIRGO payload and making use of two thin wires in a cradle configuration to support a mirror made of silicon.
The cooling strategy, the thermal behaviour and the system mechanical response have been deeply studied while a measurement characterization campaign has been performed both at room temperature and at cryogenic temperature. In this paper, the preliminary results obtained together with the first cooling down of the 300
kg overall mass payload at about 25
K, are reported. This study will play a driving role in the design of the third generation gravitational wave detector.
PDF
