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ET: Einstein Telescope
Michele PunturoINFN Perugia
On behalf of the ET design study team
1ILIAS General meeting, Jaca Feb 2008
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
2ILIAS General meeting, Jaca Feb 2008
1st generation GW detectors sensitivities
ILIAS General meeting, Jaca Feb 2008 3 ESO – May 2, 2006 G.Losurdo – INFN Firenze 310
-24
10-23
10-22
10-21
10-20
10-19
10-18
1 10 100 1000 104
h (
Hz-1
/2)
Virgo
LIGO
Resonantantennas
Hz
GEO
Core Collapse@ 10 Mpc
BH-BH MergerOscillations@ 100 Mpc
Pulsars hmax – 1 yr integration
BH-BH Inspiral,z = 0.4
BH-BH Inspiral, 100 Mpc
QNM from BH Collisions, 1000 - 100 Msun, z=1
NS, =10-6 , 10 kpc
QNM from BH Collisions, 100 - 10 Msun, 150 Mpc
NS-NS Inspiral, 300 Mpc
NS-NS MergerOscillations@ 100 Mpc
1st generation detectors
Credit: P.Rapagnani
ILIAS General meeting, Jaca Feb 2008 4
“1.5 generation” sensitivities
Laser amplifier
Higher finesse, lower mirror TNM
onolithic FS suspensions
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 5
Detectionprogresses
Credit:
Richard Powell,
Beverly Berger.
From LIGO presentation G050121
10 100 1000 1000010-24
10-23
10-22
10-21
10-20
10-19
10-18
h(f
) [1
/sq
rt(H
z)]
Frequency [Hz]
1st generation: Virgo LIGO
1.5 generation: Virgo+ eLIGO
2nd generation advVirgo advLIGO
NS-NS (1.4MS):13 15/50 120/170 Mpc
NS-NS
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 7
Objectives of a 3 rd generation GW detectorsFrom 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 -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 -ray bursts
ILIAS General meeting, Jaca Feb 2008 8
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 9
ET
• 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 10
ET: Participants
ILIAS General meeting, Jaca Feb 2008 11
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 United Kingdom
7 NIKHEF The Netherlands
8 Cardiff University United Kingdom
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 12
Project organization
• 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 13
Executive board
GoverningCouncil
Science Team
Institutions Scientific community
ET Project
Information fluxes
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 14
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
Thermal Noise
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 15
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
2nd generation
10km
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
Cryogenic Optics
ILIAS General meeting, Jaca Feb 2008 16
• 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 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;
(Sapphire @ 20K β = 9 × 10−8, Fused Silica @ 300K β ~ 10−6)
ILIAS “supported” or related activities
ILIAS General meeting, Jaca Feb 2008 17
Silicon substrates
R&D activities in many European Labs:Glasgow, INFN Florence & Perugia, Jena University, …
Cryogenic Super attenuator
R&D activities in INFN Rome & Pisa
0 50 100 150 200 250 300
1.0x10-5
1.5x10-5
2.0x10-5
2.5x10-5
3.0x10-5
3.5x10-5 4th mode undoped Ta
2O
5
4th mode, TiO2 doped Ta
2O
5
Mec
hani
cal l
oss
of c
oate
d si
licon
can
tilev
er
Temperature (K)
Coatings studies
R&D activities in many European Labs:Glasgow, INFN Perugia, LMA-Lyon, MPG Hannover, …
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 18
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
10km10km, 20K
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
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 19
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
10km, 20K10km, 20K, 10cm
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
Non Gaussian Beams• Thermal noise in a GW interferometric detector
could be further reduced by using “flatter” beams:
ILIAS General meeting, Jaca Feb 2008 20
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 21
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
10km, 20K, 10cm, non gauss
10km, 20K, 10cm
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
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 22
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
800kW
3MWShot Noise
Shot Noise
• High laser power
Shot Noise
• High laser power
• Squeezing
• Long interferometer arms
Shot Noise
• High laser power
(maybe 1550nm for silicon;
less thermal lensing @ 25K)
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 23
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
800kW
3MW
3MW, 6dB3MW, 6dB, 10km
3MW, 6dB, 10km, 3ifos
Shot Noise
• High laser power
Shot Noise
• High laser power
• Squeezing
Shot Noise
• High laser power
• Squeezing
• Long interferometer arms
Shot Noise
• High laser power
• Squeezing
• Long interferometer arms
• Multiple colocated interferometers
Co-located interferometers• “Old” idea still under debate
– Possible implementation: 3 detectors in a triangle configuration
ILIAS General meeting, Jaca Feb 2008 24
Rüdiger, ‘85
Angular response of a standard ITF
Angular responseof the triangle configurationCredit: Cella, Vicerè
Antenna Patterns:
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 25
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19
• Underground operation
• Homogeneous ‚soil‘Seismic
Underground operations
ILIAS General meeting, Jaca Feb 2008 26
• LISM: 20 m Fabry-Perot interferometer, R&D for LCGT, moved from Mitaka (ground based) to Kamioka (underground)• Seismic noise strongly reduced
Credit: K.Kuroda
102 overall gain103 at 4 Hz
Seismic Isolation Shortcut
ILIAS General meeting, Jaca Feb 2008 27Figure: M.Lorenzini
Newtonian Noise!
NewtonianNoisecredit: G.Cella
ILIAS General meeting, Jaca Feb 2008 28
• Surface waves give the main contribution to newtonian noise
Credit: G.Cella
Surface waves die
exponentially with depth
Compression wavesSurface waves
Credit: G. CellaCredit: G. Cella
NN reduction of 104 @5 Hz
with a 20 m radius cave
Cave radius [m]
Redu
ction
fact
or
(Compression waves not included)
106 overall reduction (far from surface)102 less seismic noise x 104 geometrical reduction
3 main noise sources
ILIAS General meeting, Jaca Feb 2008 29
1st generation2nd generation3rd generation
1 10 100 1000 1000010
-25
10-24
10-23
10-22
10-21
10-20
10-19 1st generation
2nd generation3rd generation
New
tonian
noise
Ground surface
Underground
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
ILIAS General meeting, Jaca Feb 2008 30
Executive board
GoverningCouncil
Science Team
Institutions Scientific community
ET Project• 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
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 31
Conclusions: Planning
ILIAS General meeting, Jaca Feb 2008 32
´06´06 ´07´07 ´08´08 ´09´09 ´10´10 ´11´11 ´12´12 ´13´13 ´14´14 ´15´15 ´16´16 ´17´17 ´18´18 ´19´19 ´20´20 ´21´21 ´22´22
VirgoVirgo
GEOGEO
LIGOLIGO
LISALISA
E.T.E.T.
Virgo+
LIGO+
Advanced Virgo
GEO HF
Advanced LIGO
DS PCP Construction Commissioning
HanfordHanford
LivingstonLivingston
Launch Transfer data
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