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Chambery, February 27th, 2007 1
Raffaele FlaminioEGO and IN2P3/LAPP
N5/WG3:Future GW detectors in Europe
Summary- Introduction- Purposes of WG3- The GW roadmap
- Virgo+ and GEO-HF- Advanced Virgo- 3rd generation ITF
- Conclusions http://www.ego-gw.it/ILIAS-GW/
Chambery, February 27th, 2007 2
Present GW detectors possibilities
• Gravitational collapses in the galaxy (or nearby galaxies)• Test upper limits of known galactic pulsars (and look for unknown ones)• Search for coalescing neutron stars up to a max distance of ~30 Mpc• Search for merger of binary black holes up to a max distance of ~150 Mpc• The unknown
Chambery, February 27th, 2007 3
Toward GW astronomy
• Present detectors will test upper limits
• Even in the optimistic case rate too low to start GW astronomy
• Need to improve the sensitivity
• Increase the sensitivity by 10 ⇒ increase the probed volume by 1000
• Plans to improve the present detectors
Chambery, February 27th, 2007 4
Present limitations…. and ways to improve
1 10 100 1000 1000010-23
10-22
10-21
10-20
10-19
10-18
(a) Virgo Nominal sensitivity (b) Seismic noise (c) Pendulum thermal noise (d) Mirror thermal noise (e) Shot Noise
h(f)
[1/
sqrt
(Hz)
]
Frequency [Hz]
(a)
(b)
(c)
(d)
(e)
• Seismic noise- better active seismic isolation - longer and softer seismic isolation system- seismic noise reduction ! Go undergound
Chambery, February 27th, 2007 5
Present limitations…. and ways to improve
1 10 100 1000 1000010-23
10-22
10-21
10-20
10-19
10-18
(a) Virgo Nominal sensitivity (b) Seismic noise (c) Pendulum thermal noise (d) Mirror thermal noise (e) Shot Noise
h(f)
[1/
sqrt
(Hz)
]
Frequency [Hz]
(a)
(b)
(c)
(d)
(e)
• Pendulum thermal noise- decrease pendulum friction- better suspensions wires- better wire clamping- monolithic suspensions- cryogenic suspensions
Chambery, February 27th, 2007 6
Present limitations…. and ways to improve
1 10 100 1000 1000010-23
10-22
10-21
10-20
10-19
10-18
(a) Virgo Nominal sensitivity (b) Seismic noise (c) Pendulum thermal noise (d) Mirror thermal noise (e) Shot Noise
h(f)
[1/
sqrt
(Hz)
]
Frequency [Hz]
(a)
(b)
(c)
(d)
(e)
• Mirror thermal noise- decrease mirror internal friction- presently limited by friction in the coating- first decrease coating mechanical losses- then better mirror substrates- then low temperatures
Chambery, February 27th, 2007 7
• Shot noise- Increase power stored in the interferometer (increase laser power, decrease optical losses)- But attention to:1) thermal deformation
- improve thermal compensation- decrease light absorption
2) radiation pressure noise - increase mirror mass- optimize optical configuration (signal recycling)- use non classical light (light squeezing)
Present limitations…. and ways to improve
1 10 100 1000 1000010-23
10-22
10-21
10-20
10-19
10-18
(a) Virgo Nominal sensitivity (b) Seismic noise (c) Pendulum thermal noise (d) Mirror thermal noise (e) Shot Noise
h(f)
[1/
sqrt
(Hz)
]
Frequency [Hz]
(a)
(b)
(c)
(d)
(e)
Chambery, February 27th, 2007 8
Scope of the ILIAS-N5 WG3• Objective of WG3: Discuss plans for the enhancement of performances of the European GW detectors
• Questions for WG3- what are the technologies available now and in the future ?- what is the best strategy to upgrade existing detectors ?- what is the road toward new detectors/infrastructures ?
• Eight people appointed as permanent members of WG3:- three from Virgo, two from GEO and three from the resonant detectors- meetings open and other experts invited at the meetings
• Group coordinated by M. Punturo (INFN Perugia) and H. Lueck (MPI Hannover)
• Ten meetings held since the beginning of ILIASNext meeting: Amsterdam, Netherland, March 9 2007http://www.ego-gw.it/ILIAS-GW
Chambery, February 27th, 2007 9
WG3 implementation plan
- Finalization ofthe ‘White book’- Discussion of‘White book’ withfunding agencies- Writing of finalreport
- Evaluation ofcompatibility amongproposed long-termscenarios- Draft of a credibleplan for a Europeannetwork ofgravitational wavesdetectors at the 2012horizon
- Presentation of shortterm plan to thefunding agencies- Definition of realisticobjectives for newgeneration antennas- Definition ofrequirements andneeds for possible nextgeneration antennas
- Evaluation of proposedshort term improvements- Preparation of adocument describing aproposition for shortterm improvements.
- Working groupsetup- Definition of a listof possible short-termimprovements
YEAR 5(2008-09)
YEAR 4(2007-08)
YEAR 3(2006-07)
YEAR 2(2005-06)
YEAR 1(2004-05)
• Phase I: identify and propose short term improvements of existing detectors
• Phase II: study new generation antenna
Chambery, February 27th, 2007 10
The situation in 2004 (ILIAS t0)• Cryogenic resonant detectors- bars in operation since several years (AURIGA, Explorer, Nautilus)- development/study of spherical detectors in the Netherlands and in Italy- start of DUAL R&D in Italy
• GEO and LIGO under commissioning- LIGO had just reached resonant bars sensitivity but with much larger bandwidth
• Virgo commissioning just started- interferometer ‘first lock’ in 2004
Chambery, February 27th, 2007 11
The situation today• Cryogenic resonant detectors- bars operating continuously; but upgrade to ultra-cryogenic temperature cancelled- development of spherical detector (miniGRAIL) in the Netherlands (cancelled in Italy)- DUAL R&D going on in Italy
• LIGO reached design sensitivity- long data taking in progress- Advanced LIGO approved by NSF construction to start in 2008
• Virgo and GEO under commissioning- approaching design sensitivity- Virgo - LSC data sharing agreement signed
Chambery, February 27th, 2007 12
WG3: Short term improvements• Discussions initially considered a wide range of technologies
• Then progressively more and more focus on laser interferometer detectors
• Short term improvements of Virgo and GEO- discussion took advantage from a nice complementarities- Virgo:advanced seismic isolation, traditional steel wire mirror suspension, no signal recycling- GEO:simpler seismic isolation but integrating advanced technologies such as monolithicsuspensions and signal recycling
• Two short term improvements proposed to the institutions and approved in 2005- GEO-HF- Virgo +
• And then study Advanced Virgo design
Chambery, February 27th, 2007 13
From GEO to GEO-HF• GEO-HF- not the name of a new detector but rather the name of a program- sequential upgrades of GEO- prototype research to prepare these upgrades
• Motivations- provides scientifically interesting data until Advanced Interferometers will come on-line- support transit of 3rd generation interferometer research to detector subsystems or detector configuration (as it was the case with GEO and 2nd generation ITF)
• Envisaged upgrades:- increase circulating power- optimise signal recycling- use of squeezed light- reduce coating thermal noise (if possible).
• Timeline: start upgrading after extended data taking 2007/2008
Potential sensitivity curves
Chambery, February 27th, 2007 14
1 10 100 1000 1000010-23
10-22
10-21
10-20
10-19
10-18
h(f)
[1/s
qrt(
Hz)
]
Frequency [Hz]
50W/2 + new losses model 50W/2 + current mirrors Nominal Virgo 50W/2 + new losses model+FS suspensions Virgo+ with Newtonian Noise
The Virgo+ upgrade• Virgo has already an “advanced” seismic isolation system
• Possibility to improve the sensitivity with a set medium scale incremental improvementsCompatibility with the main Virgo subsystemsSame optical lay-outLimited shutdownLimited commissioning
• Planned upgrades- Fused silica suspensions - Larger laser power: 20W → 50W
⇒ mirror shape thermal compensation- Electronics and control system
• Coalescing binaries ‘horizon’ maximum distance for optimally oriented source
Virgo
Virgo+
584 Mpc145 MpcBH-BH
114 Mpc30 MpcNS-NS
Virgo+Virgo
Coalescing binaries rates increased by ~ 30-100
Chambery, February 27th, 2007 15
Virgo+ status and plan• Status of the project:- approved by CNRS and INFN- new mirror substrates purchased- infrastructure for fused silica fiber production and mirror assembly ready- laser amplifier to be delivered next fall- new electronics being developed
• Plan- test prototype of fused silica suspension in 2007- start upgrade after extended Virgo data taking- shut down for upgrade ~ 2008
Chambery, February 27th, 2007 16
Toward Advanced Virgo• Sensitivity goal: ×10 better than Virgo (similar to Advanced LIGO)
• Expected area of improvement:- High power lasers and injection optics- Laser beam geometry- Interferometer optical configuration- Signal recycling- Mirror coatings and shape- Monolithic suspensions- Larger mirrors
• A possible sensitivity
• Envisaged timeline- by 2009: R&D and final design- 2009-10: engineering> 2010: construction
Chambery, February 27th, 2007 17
• The role of WG3:- Animate discussions about available technologies to improve interferometer sensitivity
e.g. Virgo-LIGO thermal noise workshop held in Cascina last fall- Triggered participation of GEO scientists into the Advanced Virgo design
Virgo-GEO MOU signed in 2006
- Support participation of GEO scientists to Advanced Virgo working groups
Advanced Virgo and WG3
Chambery, February 27th, 2007 18
Toward Advanced Virgo design• Most recent outcome of Advanced Virgo working group:
“Guidelines for Advanced Virgo R&D”, transmitted to CNRS and INFN
• EGO just launched an R&D program to support the preparation of Advanced Virgo along the lines traced in “Guidelines for Advanced Virgo R&D”
• Next milestone: preliminary Advanced Virgo design and costing by the end of 2007
Chambery, February 27th, 2007 19
WG3 implementation plan
- Finalization ofthe ‘White book’- Discussion of‘White book’ withfunding agencies- Writing of finalreport
- Evaluation ofcompatibility amongproposed long-termscenarios- Draft of a credibleplan for a Europeannetwork ofgravitational wavesdetectors at the 2012horizon
- Presentation of shortterm plan to thefunding agencies- Definition of realisticobjectives for newgeneration antennas- Definition ofrequirements andneeds for possible nextgeneration antennas
- Evaluation of proposedshort term improvements- Preparation of adocument describing aproposition for shortterm improvements.
- Working groupsetup- Definition of a listof possible short-termimprovements
YEAR 5(2008-09)
YEAR 4(2007-08)
YEAR 3(2006-07)
YEAR 2(2005-06)
YEAR 1(2004-05)
• Phase I: identify and propose short term improvements of existing detectors
• Phase II: study new generation detectors
Chambery, February 27th, 2007 20
• Need to improve sensitivity at low frequency (1Hz – 10 Hz)- most interesting physics is there- mergers of intermediate mass black holes at cosmological distances, stochastic background, galactic neutron stars, ….
• Advanced interferometers will reach the limit of present infrastructures: seismic noise- acting on mirror suspensions- acting directly on mirrors via gravity gradients
• Need to reduce seismic noiseGo underground
• Other advantages:- No wind- Easier to build longer arms (10 km?)- Easier to imagine longer suspensions (100 m?)
Beyond Advanced Virgo
Seismic noise Gravity gradient noise
Chambery, February 27th, 2007 21
• A possible design
3rd generation interferometer
Upper experimental hall
Credit: R.De Salvo
50-100 m well to accomodatelong suspension for low frequency goal
Ellipsoidal/spherical cave fornewtonian noise reduction
10 km tunnel
Rüdiger, ‘85
Chambery, February 27th, 2007 22
3rd generation interferometer• And then need to reduce thermal noise
Go cryogenics
• One of the goal of the STREGA JRA within ILIAS
• Other third generation ITF keywords:- squeezed light- massive mirrors- ….
• Sensitivity goal: ×10 better than Adv ITF Enter the 10-25 scale
• WG3 meetings now focus on this subject
• Working on a design study proposal within FP7 (with participants from all the main existing projects and institutions CNRS, INFN, PPARC, MPI, Nikhef, ….)
Chambery, February 27th, 2007 23
• Existing detectors are in the process of testing theoretical upper limits• Still space to improve their sensitivity• Further improvements will need a new facility (FP7)
• An exciting experimental program in front of us• WG3 of ILIAS-GWA contributing to the definition of this program
Conclusions