1. ET: Einstein Telescope
Michele Punturo
INFN Perugia
On behalf of the ET design study team
ILIAS General meeting, Jaca Feb 2008

2. Evolution of the current GW detectors
Current Gravitational Wave interferometric detectors have a well defined evolution line in the next 5-7 years
LIGO just completed its S5 scientific run
Virgo completed in October 07 its first long scientific run in parallel with LIGO
Both the detectors are in upgrade/commissioning mode to implement their 1.5 generation upgrade step (Virgo+, enhanced LIGO)
GEO is covering (“astrowatch” mode) the down time of LIGO and Virgo in collaboration with the resonant bar detectors
… see G.Losurdo Talk
ILIAS General meeting, Jaca Feb 2008

3. 1st generation GW detectors sensitivities10
-24
-23
-22
-21
-20
-19
-18 1
100
1000 4
h (Hz-1/2)
Virgo
LIGO
Resonant
antennas Hz
GEO
Core Collapse
@ 10 Mpc
BH-BH Merger
Oscillations
@ 100 Mpc
Pulsars
hmax – 1 yr integration
BH-BH Inspiral,
z = 0.4
BH-BH Inspiral, 100 Mpc
QNM from BH Collisions,
Msun, z=1
NS, e
=10 -6
, 10 kpc
Msun, 150 Mpc
NS-NS Inspiral, 300 Mpc
NS-NS Merger
1st generation detectors
Credit: P.Rapagnani
ILIAS General meeting, Jaca Feb 2008
ESO – May 2, G.Losurdo – INFN Firenze 3

4. “1.5 generation” sensitivities
Monolithic FS suspensions
Laser amplifier
Higher finesse, lower mirror TN
ILIAS General meeting, Jaca Feb 2008

5. ILIAS General meeting, Jaca Feb 2008
Advanced detectors
Enhanced detectors are a step toward the realization of the 2nd generation detectors (“advanced”)
Also GEO will participate to the network of enhanced detectors with an upgraded version, “specialized” in the high frequency regime thanks (mainly) to the signal recycling technology
GEO HF
They are based on “small” changes of the current detectors with available technologies that anticipate the next step
Advanced detectors will be online in the >2013 timeslot
They will be based on known technologies currently under preliminary engineering phase
High power laser (~200W) and compliant optics
Lower thermal noise mirrors (substrates and coatings)
Lower thermal noise suspensions (FS monolithic suspensions)
Better seismic isolation
Active filtering in LIGO
Focused improvements of the Virgo Super-Attenuator
Signal recycling
ILIAS General meeting, Jaca Feb 2008

6. Detection progresses NS-NS (1.4MS): 13  15/50  120/170 Mpc NS-NS
Credit:
Richard Powell,
Beverly Berger.
From LIGO presentation G050121
Detection progresses
NS-NS (1.4MS):
13  15/50  120/170 Mpc
NS-NS

7. 3rd generation detectors
Second generation detectors:
Will permit the detection of Gravitational Waves (GW)
Will open the era of the GW astronomy
Will be the “core business” of the next decade in experimental GW research
But can we look beyond?
Precision GW astronomy needs high SNR to determine the parameters of the astrophysical process
Interesting phenomena involves massive bodies that requires low frequency sensitivity in GW detectors
We need to think to 3rd generation GW detectors
ILIAS General meeting, Jaca Feb 2008

8. ILIAS General meeting, Jaca Feb 2008
Objectives of a 3 rd generation GW detectors From detection and initial GW astronomy to precision GW astronomy
Fundamental Physics: Test general relativity in the strongly non-linear regime
Initial and advanced detectors won’t have the sensitivity required to test strong field GR (too low SNR)
Most tests are currently quoted in the context of LISA, but in a different frequency range
We need to have good enough SNR for rare BBH mergers which will enable strong-field test of GR
Black hole physics:
What is the end state of a gravitational collapse?
Astrophysics: Take a census of binary neutron stars in the high red-shift Universe
Adv VIRGO/LIGO might confirm BNS mergers, possibly provide links to g-ray bursts
3rd generation GW detectors could do much more: see different classes of sources (NS-NS, NS-BH) and contribute to resolve the enigma in the variety of g-ray bursts
ILIAS General meeting, Jaca Feb 2008

9. How to arrive to an European 3rd generation GW Observatory?
Long preparatory path, already started:
ILIAS played a determinant role:
ILIAS-GW-WP3 realized the correct environment where to discuss, at European level, the evolution of the current detectors and where to merge the efforts addressed to the proposition of a 3rd generation GW observatory
It supported the meetings, the workshops and the preliminary studies
All the ET proposal writing meetings have been supported by WP3
WP3 has been also the core of the new WG6 (GW) in the ASPERA road-mapping activity
ILIAS-JRA3 (STREGA) partially supported R&D activities in thermal noise issues for 3rd generation GW detectors
European Science Foundation supported an exploratory workshop (Perugia, Sept 2005) that has been a milestone in the definition of the strategy for the proposal of a new Observatory
FP7 Design Study has been the perfect environment where to synthesize our ideas in a proposal and compete with other excellent proposals
ILIAS General meeting, Jaca Feb 2008

10. ILIAS General meeting, Jaca Feb 2008
ET: Einstein Telescope
An European 3rd Generation Gravitational Wave Observatory
Conceptual design study proposed at the May 2007 FP7 call
Capacities
Research Infrastructures
Collaborative projects
ILIAS General meeting, Jaca Feb 2008

11. Participant organization name
ET: Participants
Participant no.
Participant organization name
Country 1
European Gravitational Observatory
Italy-France 2
Istituto Nazionale di Fisica Nucleare
Italy 3
Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V., acting through Max-
Planck-Institut für Gravitationsphysik
Germany 4
Centre National de la Recherche Scientifique
France 5
University of Birmingham
United Kingdom 6
University of Glasgow 7
NIKHEF
The Netherlands 8
Cardiff University
ILIAS General meeting, Jaca Feb 2008

12. ET: Status of the project
The proposal passed the first selection and now we are in an advanced negotiation phase
We agreed a budget reduction to 3M€ for 38Months of activity
Main costs: man power and travels
Description of Work document accepted by the European Officer
We are submitting the signed documents to prepare the Grant Agreement
Consortium Agreement under final definition
ILIAS General meeting, Jaca Feb 2008

13. Project organization Project organization driven by the “Physics”:
Project Coordinator
Scientific Coordinator
Secretary
WP1 coordinator: Infrastructures
Task responsible
WP2 coordinator: suspensions
Task reponsible
WP3 coordinator: Topology
WP4 coordinator: Astrophysics
WP5: Management
Executive board
Governing
Council
Science Team
Institutions
Scientific community
ET Project
Information fluxes
Project organization driven by the “Physics”:
4 working groups are devoted to the major technical and scientific issues
Let see the main technical aspects:
ILIAS General meeting, Jaca Feb 2008

14. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
Seismic
Shot Noise
Thermal Noise
ILIAS General meeting, Jaca Feb 2008

15. ILIAS General meeting, Jaca Feb 2008
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
3 main noise sources
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
2nd generation
10km
ILIAS General meeting, Jaca Feb 2008

16. ILIAS General meeting, Jaca Feb 2008
Cryogenic Optics
Test masses and suspensions thermal noise reduces at low temperature: <X2> ~ T
Thermoelastic noise of the mirror substrates and coatings decrease: <X2> ~ α T2
Thermal expansion rate a decreases at low temperature;
Mechanical Q of some materials increases at low temperature
Thermal lensing:
Thermal conductivity increases and consequently reduces thermal gradients on the coating;
Refraction index variation with temperature is very small at low temperature;
20K β = 9 × 10−8, Fused 300K β ~ 10−6)
ILIAS General meeting, Jaca Feb 2008

17. ILIAS “supported” or related activities
Silicon substrates
R&D activities in many European Labs:
Glasgow, INFN Florence & Perugia, Jena University, …
Coatings studies
R&D activities in many European Labs:
Glasgow, INFN Perugia, LMA-Lyon, MPG Hannover, …
Cryogenic Super attenuator
R&D activities in INFN Rome & Pisa
ILIAS General meeting, Jaca Feb 2008

18. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
10km
10km, 20K
ILIAS General meeting, Jaca Feb 2008

19. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
10km, 20K
10km, 20K, 10cm
ILIAS General meeting, Jaca Feb 2008

20. ILIAS General meeting, Jaca Feb 2008
Non Gaussian Beams
Thermal noise in a GW interferometric detector could be further reduced by using “flatter” beams:
ILIAS General meeting, Jaca Feb 2008

21. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
Thermal Noise
Long interferometer arms
Cryogenic optics
Large beams, large optics
Non-gaussian beams
Improved coatings
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
10km, 20K, 10cm
10km, 20K, 10cm, non gauss
ILIAS General meeting, Jaca Feb 2008

22. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
Shot Noise
High laser power
Squeezing
Long interferometer arms
Shot Noise
High laser power
(maybe 1550nm for silicon;
less thermal 25K)
Shot Noise
High laser power
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
800kW
3MW
Shot Noise
ILIAS General meeting, Jaca Feb 2008

23. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
Shot Noise
High laser power
Squeezing
Shot Noise
High laser power
Shot Noise
High laser power
Squeezing
Long interferometer arms
Shot Noise
High laser power
Squeezing
Long interferometer arms
Multiple colocated interferometers
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
800kW
3MW
3MW, 6dB
3MW, 6dB, 10km
3MW, 6dB, 10km, 3ifos
ILIAS General meeting, Jaca Feb 2008

24. Co-located interferometers
“Old” idea still under debate
Possible implementation: 3 detectors in a triangle configuration
Rüdiger, ‘85
Antenna Patterns:
Angular response
of a standard ITF
Angular response
of the triangle configuration
Credit: Cella, Vicerè
ILIAS General meeting, Jaca Feb 2008

25. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
Underground operation
Homogeneous ‚soil‘
Seismic
ILIAS General meeting, Jaca Feb 2008

26. Underground operations
LISM: 20 m Fabry-Perot interferometer, R&D for LCGT, moved from Mitaka (ground based) to Kamioka (underground)
Seismic noise strongly reduced
102 overall gain
103 at 4 Hz
Credit: K.Kuroda
ILIAS General meeting, Jaca Feb 2008

27. Seismic Isolation Shortcut
Newtonian Noise!
ILIAS General meeting, Jaca Feb 2008
Figure: M.Lorenzini

28. Newtonian Noise credit: G.Cella
Compression waves
Surface waves
Surface waves give the main contribution to newtonian noise
(Compression waves not included)
Reduction factor
NN reduction of Hz
with a 20 m radius cave
Surface waves die
exponentially with depth
Cave radius [m]
102 less seismic noise x 104 geometrical reduction
106 overall reduction (far from surface)
ILIAS General meeting, Jaca Feb 2008
Credit: G.Cella

29. ILIAS General meeting, Jaca Feb 2008
3 main noise sources
1st generation
2nd generation
3rd generation 1 10
100
1000
10000
-25
-24
-23
-22
-21
-20
-19
1st generation
2nd generation
3rd generation
Newtonian noise
Underground
Ground surface
ILIAS General meeting, Jaca Feb 2008

30. ILIAS General meeting, Jaca Feb 2008
Conclusions
The target of the four Working Groups in the ET project is to try to transform these (and many other) ideas in a coherent conceptual design
It is an huge job for a restricted set of persons
ET is an emerging facility for the whole Europe and we don’t want to limit the contribution to the founding team/institutions
The proposal writers created in the project structure a special body that permits the exchange with a larger Scientific Community
The Science Team has been considered extremely important by the project referee and already promoted the interest of European and extra-European Scientists
If you are interested, please, contact us
Executive board
Governing
Council
Science Team
Institutions
Scientific community
ET Project
ILIAS General meeting, Jaca Feb 2008

31. ILIAS General meeting, Jaca Feb 2008
Comments
ILIAS-N5 played a fundamental role in building-up the framework where ET project is born
ILIAS-JRA3 partially supported the technological development needed to “think” to ET
ET is a conceptual design, with any R&D support:
It needs a further support from the ILIAS (-next) community
ILIAS General meeting, Jaca Feb 2008

32. Conclusions: Planning
You are here
´06
´07
´08
´09
´10
´11
´12
´13
´14
´15
´16
´17
´18
´19
´20
´21
´22
Virgo
GEO
LIGO
LISA
E.T.
Virgo+
Advanced Virgo
GEO HF
Hanford
LIGO+
Advanced LIGO
Livingston
Launch Transfer data DS
PCP
Construction
Commissioning
data
ILIAS General meeting, Jaca Feb 2008