1. Some ideas on ET1 site Adalberto Giazotto INFN Pisa- EGO

2. Introduction ET will be a network of detectors whose target is the systematic observation of the Universe by means of Gravitational Waves: i.e. GW astronomy. GW astronomy implies, obviously, determination of GW sources celestial coordinates. The most efficient and precise way of measuring source celestial coordinates is by means of GW event time of flight measurement. This method requires several interferometers well spaced around the Earth in the way of attaining the highest angular resolution.

3. 4 well spaced ITF’s determine univocally GW source Celestial Coordinates. Per example angular resolution of the V-L network are : Virgo-LIGO Declinazione: 4°30‘ Ascensione retta: 3° 32‘ Courtesy Simona Birindelli Virgo-LIGO-AIGO Declinazione: 2° 52‘ Ascensione retta:1° 51‘ Courtesy Simona Birindelli LIGO+AIGOLIGO For this reason I refere to ET1 as the first of, at least, 4 interferometer which will form the ET network

4. Correlation between detectors Another reason for getting well separated ITF’s for ET is that this configuration has the lowest correlation between single network detectors. For these reasons I refere to ET1 as the first of, at least, 4 interferometer which will form the ET network

5. ET a Global network of Detectors Coherent Analysis: why? -Sensitivity increase -Source direction determination from time of flight differences -Polarizations measurement -Test of GW Theory and GW Physical properties Astrophysical targets - Far Universe expansion rate Measurement -GW energy density in the Universe -Knowledge of Universe at times close to Planck’s time

6. ET Sensitivity Harald Lück for the European Gravitational-Wave Community

7. TAMA 300 GEO600 LIGO Virgo AURIGA, NAUTILUS, EXPLORER GW DETECTORS SENSITIVITY

8. Some exercise:Use of Superattenuators for ET 1) Inverted Pend. 40 mHz 2) 50 m tall mechanical filter chain By assuming a seismic noise underground 10 -9 m/sqrt(Hz)@1Hz, from theTF optimized at 1Hz we obtain h(1Hz)= 2.610 -22 /sqrt(Hz ~50 m N 1 Hz 2 Hz --------------------------- {3, 1.6*10-7, 5.4*10-10} {4, 4.8*10-8, 3.3*10-11} {5, 2.6*10-8, 3.4*10-12} {6, 2.3*10-8, 6.7*10-12} {7, 2.1*10-8, 2.6*10-12} Optimized at 1Hz Courtesy G. Cella Horizontal

9. ET sens. 2 HZ Superattenuator NEWTONIAN

10. Isolation in Vertical Direction In Virgo, SA Vertical attenuation has been tuned to the horizontal one evaluated with length module of 1m. Considering length module of 7m we obtain: This frequency can be easily obtained both by tuning magnetic antispring or geometrical springs.

14. 15-20 m diam. 10 km 4k 300k Tunnel standard ~100 m 15 m clean room

15. 10 km 4k 300k Tunnel standard 15-20 m ~100 m 15 m clean room

17. Some exercise:Use of Superattenuators for ET 1) Inverted Pend. 40 mHz 2) 50 m tall mechanical filter chain By assuming a seismic noise underground 10 -8 m/sqrt(Hz) @1Hz, from the TF optimized at 2Hz we obtain h(2Hz)=10 -25 /sqrt(Hz)<<10 -22 /sqrt(Hz) N 1 Hz 2 Hz --------------------------- {3, 1.6*10-7, 5.4*10-10} {4, 4.8*10-8, 3.3*10-11} {5, 2.7*10-8, 3.3*10-12} {6, 2.8*10-8, 4.9*10-13} {7, 6.3*10-8, 1.0*10-13} Optimized at 2 Hz N 1 Hz 2 Hz --------------------------- {3, 1.6*10-7, 5.4*10-10} {4, 4.8*10-8, 3.3*10-11} {5, 2.6*10-8, 3.4*10-12} {6, 2.3*10-8, 6.7*10-12} {7, 2.1*10-8, 2.6*10-12} Optimized at 1Hz ~50 m Courtesy G. Cella