Some ideas on ET1 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.

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-LIGODeclinazione: 4°30‘Ascensione retta: 3° 32‘ Courtesy Simona Birindelli

Virgo-LIGO-AIGODeclinazione: 2° 52‘Ascensione retta:1° 51‘ Courtesy Simona Birindelli

LIGO+AIGOLIGO

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

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

TAMA 300

GEO600

LIGO

Virgo

AURIGA, NAUTILUS, EXPLORER

GW DETECTORS SENSITIVITY

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-

9m/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

ET sens.

2 HZ

Superattenuator

NEWTONIAN

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.

1

1 100.16 0.4

2 1m

gHz

L

7

1 100.16 0.2

2 7m

gHz

L

15-20 m diam.

10 km

10 km4k

300k

Tunnel standard

~100 m

15 m

clean room

10 km

10 km4k

300k

Tunnel standard

15-20 m

~100 m

15 m

clean room

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 10-8m/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. CellaCourtesy G. Cella