Some ideas on ET 1 site Adalberto Giazotto

Some ideas on ET 1 site Adalberto Giazotto INFN Pisa- EGO

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 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.

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‘ Virgo-LIGO-AIGO Declinazione: 2° 52‘ Ascensione retta: 1° 51‘ Courtesy Simona Birindelli LIGO+AIGO

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 ET 1 as the first of, at least, 4 interferometer which will form the ET network

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

ET Sensitivity Harald Lück for the European Gravitational-Wave Community

GW DETECTORS SENSITIVITY TAMA 300 GEO 600 AURIGA, NAUTILUS, EXPLORER Virgo LIGO

Some exercise: Use of Superattenuators for ET 1) Inverted Pend. 40 m. Hz 2) 50 m tall mechanical filter chain N 1 Hz 2 Hz -------------- {3, 1. 6*10 -7, 5. 4*10 -10} {4, 4. 8*10 -8, 3. 3*10 -11} By assuming a {5, 2. 6*10 -8, 3. 4*10 -12} seismic noise {6, 2. 3*10 -8, 6. 7*10 -12} underground {7, 2. 1*10 -8, 2. 6*10 -12} 10 -9 m/sqrt(Hz)@1 Hz, from the. TF optimized at 1 Hz we obtain Horizontal h(1 Hz)= 2. 610 -22/sqrt(Hz Optimized at 1 Hz Courtesy G. Cella ~50 m

NEWTONIAN ET sens. Superattenuator 2 HZ

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

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

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

Some exercise: Use of Superattenuators for ET 1) Inverted Pend. 40 m. Hz 2) 50 m tall mechanical filter chain 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 1 Hz Courtesy G. Cella 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} ~50 m Optimized at 2 Hz Courtesy G. Cella By assuming a seismic noise underground 10 -8 m/sqrt(Hz) @1 Hz, from the TF optimized at 2 Hz we obtain h(2 Hz)=10 -25/sqrt(Hz)<<10 -22/sqrt(Hz)