The Einstein Telescope projectMichele PunturoINFN Perugia and EGOOn behalf of the ET Design Study Teamhttp://www.et-gw.eu/

1Einstein Telescope

The Einstein Telescope project aims to the realization of a third generation of GW observatory

The Einstein Telescope

Einstein Telescope2

Participant Country

EGO ItalyFrance

INFN Italy

MPG Germany

CNRS France

University of Birmingham UK

University of Glasgow UK

Nikhef NL

Cardiff University UK

The Einstein Telescope project aims to the realization of a third generation of GW observatory

The Einstein Telescope project is currently in its conceptual design study phase, supported by the European Community FP7 with about 3M€ from May 2008 to July 2011.

The target of this design phase is to understand the feasibility of a new generation of GW observatory that will permit to gain one order of sensibility

The main deliverable, at the end of these 3 years, will be a conceptual design of such as infrastructure

GW Astronomy ?

visibleInfrared

408MHz WMAP

X-ray g-ray

GRB

GW ?

Current e.m. telescopes are mapping the Universe in all the wavelengths detectable from the Earth and from the space.

Gravitational wave telescopes, having a comparable sight distance, could complement the e.m. observation opening the GW astrophysics era

Thanks to the small interaction between graviton and the matter , GW are the best messenger to investigate the first instants of the Universe

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Det

ectio

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.u.)

GW interferometer past evolutionEvolution of the GW detectors (Virgo example):

2003

Infrastructure

realization and

detector assembling

2008

Sameinfrastructure

Proof of the working principle

Commissioning

& first ru

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Upper Limit physics

GW interferometer present evolutionEvolution of the GW detectors (Virgo example):

2003

Infrastructure

realization and

detector assembling

2008

Sameinfrastructure

Proof of the working principle

Upper Limit physics

2011

enhanceddetectors

Sameinfrastructure

Test of “advanced” techsUL physics

2017

Sameinfrastructure

Advanced

detectors

First detection

Initial astrophysics

Commissioning

& first ru

ns

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3rd generation?Evolution of the GW detectors (Virgo example):

2003

Infrastructure

realization and

detector assembling

2008

Sameinfrastructure

Proof of the working principle

Upper Limit physics

2011

enhanceddetectors

Sameinfrastructure

Test of “advanced” techsUL physics

2017Same

infrastructure

Advanced

detectors

First detection

Initial astrophysics

2022

SameInfrastructure

(20 years old for Virgo, even more for LIGO & GEO600)

Commissioning

& first ru

ns

Precision Astrophysics

Cosmology ?

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Limit of the current infrastructures

Physics Beyond Advanced Detectors GW detection is expected to occur in the advanced detectors. The 3rd generation will focus

on observational aspects: Astrophysics:

Measure in great detail the physical parameters of the stellar bodies composing the binary systems NS-NS, NS-BH, BH-BH Constrain the Equation of State of NS through the measurement

of the merging phase of BNS of the NS stellar modes of the gravitational continuous wave emitted by a pulsar NS

Contribute to solve the GRB enigma Relativity

Compare the numerical relativity model describing the coalescence of intermediate mass black holes

Test General Relativity against other gravitation theories Cosmology

Measure few cosmological parameters using the GW signal from BNS emitting also an e.m. signal (like GRB)

Probe the first instant of the universe and its evolution through the measurement of the GW stochastic background

Astro-particle: Contribute to the measure the neutrino mass? Constrain the graviton mass measurement 7

Einstein Telescope

Targets of the Design StudyEvaluate the science reaches of ETDefine the sensitivity and performance requirements

Site requirementsInfrastructures requirementsFundamental and (main) technical noise requirementsMultiplicity requirements

Draft the observatory specsSite candidatesMain infrastructures characteristicsGeometries

Size, L-Shaped or triangularTopologies

Michelson, Sagnac, …Technologies

Evaluate the (rough) cost of the infrastructure and of the observatory

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2009

2010

2011

Transversal Writing Team

EGO STAC (May 2010) 9

TWT

How to go beyond the 2nd generation?

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10-25

10-16

h(f)

[1/s

qrt(H

z)]

Frequency [Hz]1 Hz 10 kHz

Seismic

Thermal Quantum

Seism

ic

NewtonianSusp. ThermalQuantum

Mirror thermal

3rd generation ideal target

Stressing the current technologies

Obviously a certain improvement of the sensitivity of the advanced detectors could be achieved by stressing the “current” technologies:High power lasers (1kW laser, shot noise reduction)Larger mirrors and larger beams (lower thermal noise)Better coatings (lower thermal noise, lower scattering)

But these aren’t the key elements justifying:the transition 2nd 3rd generationthe need of a new infrastructure

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3rd generation Technologies in ETInjection of squeezed light states (where the phase noise

in the ifo arms is lowered at the cost of the amplitude noise) permits to reduce HF noise

Higher order modes (LG33) resonating in the FP cavities permit to reduce the intermediate (thermal) noise effects

Cryogenic operative temperature (~10-20K) permits to suppress the thermal noise and improve the low and intermediate frequency sensitivityNew materials: Sapphire (LCGT), Silicon New coatings

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Access the very low frequencyThe most challenging requirement of a 3rd generation

GW observatory is to access, as much as possible, the ~1-10Hz frequency range

The “enemy” to fight is the seismic noise, that acts on the test masses1) Indirectly, through the suspension chain2) Directly, through the so-called gravity gradient noise

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Virgo has implemented a seismic filtering chainThe super attenuator (SA)It has been evaluated (S. Braccini et al, 2010) to be compliant

with the ET requirements, above 3Hz, if xseism<510-9/f2 m/Hz-1/2 and hSA~20m

Underground siteVirgo SA filtering capabilities are compatible with the ET

requirements from 3Hz, provided that xseims< 5×10-9/f2 m/Hz½ (Kamioca underground site specs)

Surface wave GGN reduced going underground (G.Cella 2009)

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We need an underground site: new infrastructure!

Measurements in Europe:

BFO (Black Forest Observatory): -162mBRG (Berggieshübel seism Observatory): -36mGRFO (Graefenberg borehole station): -116m

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Peterson’s Low Noise Model

Peterson’s High Noise ModelSite Investigation

http://www.et-gw.eu/

Credits: J.v.d.Brand

The infrastructurePictorial view

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~100

m

The infrastructureSchematic view

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Full infrastructure realized Initial detector(s)

implementation1 detector (2 ITF)Physics already possible

in coincidence with the improved advanced detectors

Progressive implementation 2 detector (4 ITF) Redundancy and cross-

correlation Full implementation

3 detector (6 ITF)Virtual interferometry2 polarizations

reconstruction

Cred

its: S

. Hild

ET TimelineThe t0 depends on several constrains:

Readiness of the project (completion of the design studies)Detection of GW in Advanced detectors (~2017?)Formal decisions…

We suppose to have a construction t0=2018, having a decision t0’=2016-2017

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Site prepara

tion

Site excavation

and realization

Vacuum plants

installation

First detector

installation

Pre-commissioning

and commissioning

2016 2018 2022 20242020

2nd detector

installation

ET Timeline

ASPERA-SAC, Apr2010 19

ET Design

ILIAS-next

ET 2nd DS

ET Prep. phase?

FP7 FP8?

ET Design Study: 2nd phaseWe need maintain active the network between the

scientists that currently are involved in ET, after the end of the DS

We need to pass from the conceptual design (“is it feasible?”) to the technical design (“how it should be realized?”)

Possibility to submit a new proposal to EU in 2010Who?

Enlarge the beneficiaries listWhat?

Content of the proposal Targets

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ConclusionsThe Einstein Telescope

project is concluding its first phaseWe have been able to

group a large community around a new idea

The effort and the continuity on this target must increase in the next years, although the advanced detectors realization will absorb a large fraction of the GW community resourcesOther large research

infrastructures are currently competing for the same budget

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