LIGO-G050250-00-W The Status of Gravitational-Wave Detectors Reported on behalf of LIGO colleagues...
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Transcript of LIGO-G050250-00-W The Status of Gravitational-Wave Detectors Reported on behalf of LIGO colleagues...
LIGO-G050250-00-W
The Status of Gravitational-Wave Detectors
Reported on behalf of LIGO colleagues by
Fred Raab,
LIGO Hanford Observatory
Raab: Status of Gravitational Wave Detectors
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Reach of Gravitational Wave Detectors is Rapidly Expanding
Windows of opportunity GWs a known phenomenon, but undetected as yet Resonant-bar & laser detectors Worldwide networks of terrestrial detectors LIGO: the first generation of km-scale detectors Moving toward the future
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Different Frequency Bands of Detectors and Sources
EM waves are studied over ~20 orders of magnitude» (ULF radio HE rays)
Gravitational Wave coverage over ~8 orders of magnitude» (terrestrial + space)
Audio band
space terrestrial
Raab: Status of Gravitational Wave Detectors
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Catching Waves FromOrbiting Black Holes and Neutron Stars
Sketches courtesy of Kip Thorne
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Gravitational Waves the evidence
Neutron Binary System – Hulse & TaylorPSR 1913 + 16 -- Timing of pulsars
17 / sec
Neutron Binary System• separated by 106 miles• m1 = 1.4m; m2 = 1.36m; = 0.617
Prediction from general relativity• spiral in by 3 mm/orbit• rate of change orbital period
~ 8 hr
Emission of gravitational waves
Raab: Status of Gravitational Wave Detectors
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Basic Signature of Gravitational Waves for All Detectors
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Bar Network: Int’l Gravitational Event Collaboration
Network of the 5 bar detectors almost parallel
ALLEGRO NFS-LSU http://gravity.phys.lsu.eduAURIGA INFN-LNL http://www.auriga.lnl.infn.itNIOBE ARC-UWA http://www.gravity.pd.uwa.edu.auEXPLORER INFN-CERN http://www.roma1.infn.it/rog/rogmain.htmlNAUTILUS INFN-LNF
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CERN RE 5
LNF INFNMiniGrail
Courtesy E. Coccia
Raab: Status of Gravitational Wave Detectors
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AURIGA 2nd run @ 4K: upgrades & results
new mechanical suspensions: attenuation > 360 dB at 1 kHz FEM modelled
new capacitive transducer: two-modes (1 mechanical+1 electrical) optimal mass
new amplifier: double stage SQUID
new data analysis: C++ object oriented code frame data format
Bandwidth: noise floor below 5x10-21 Hz-1/2
on a 100 Hz band
Stationary gaussian behaviour: few spurious event/h after anticoincidence veto with 20 ms all band electromagnetic glitches
Courtesy M. Cerdonio
Raab: Status of Gravitational Wave Detectors
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New Generation of “Free-Mass” Detectors Now Online
suspended mirrors markinertial frames
antisymmetric portcarries GW signal
Symmetric port carriescommon-mode info
Intrinsically broad band and size-limited by speed of light.
Raab: Status of Gravitational Wave Detectors
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The International Interferometer Network
LIGO
Simultaneously detect signal (within msec)
detection confidence locate the sources
decompose the polarization of gravitational waves
GEO VirgoTAMA
AIGO
Raab: Status of Gravitational Wave Detectors
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LIGO (Washington)(4-km and 2km)
LIGO (Louisiana)(4-km)
The Laser InterferometerGravitational-Wave Observatory
Funded by the National Science Foundation; operated by Caltech and MIT; the research focus for more than 500 LIGO Scientific Collaboration members worldwide.
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GEO 600 (Germany)600-m
Virgo (Italy)3-km
Interferometers in Europe
Raab: Status of Gravitational Wave Detectors
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TAMA 300 (Japan)(300-m)
AIGO (Australia)(80-m, but 3-km site)
Interferometers in Asia, Australia
Raab: Status of Gravitational Wave Detectors
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Spacetime is Stiff!
=> Wave can carry huge energy with miniscule amplitude!
h ~ (G/c4) (ENS/r)
Raab: Status of Gravitational Wave Detectors
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Some of the Technical Challenges
Typical Strains < 10-21 at Earth ~ 1 hair’s width at 4 light years
Understand displacement fluctuations of 4-km arms at the millifermi level (1/1000th of a proton diameter)
Control arm lengths to 10-13 meters RMS Detect optical phase changes of ~ 10-10 radians Hold mirror alignments to 10-8 radians Engineer structures to mitigate recoil from atomic
vibrations in suspended mirrors
Raab: Status of Gravitational Wave Detectors
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What Limits Sensitivityof Interferometers?
• Seismic noise & vibration limit at low frequencies
• Atomic vibrations (Thermal Noise) inside components limit at mid frequencies
• Quantum nature of light (Shot Noise) limits at high frequencies
• Myriad details of the lasers, electronics, etc., can make problems above these levels
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Time Line
First Science Data
Inauguration
19993Q 4Q
20001Q 2Q 3Q 4Q
20011Q 2Q 3Q 4Q
20021Q 2Q 3Q 4Q
20031Q 2Q 3Q 4Q
E1Engineering
E2 E3 E4 E5 E6 E7 E8 E9
S1Science
S2 S3
First Lock Full Lock all IFO's
10-17 10-18 10-19 10-20strain noise density @ 200 Hz [Hz-1/2] 10-21
Runs
10-22
E10
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Vibration Isolation Systems
» Reduce in-band seismic motion by 4 - 6 orders of magnitude» Little or no attenuation below 10Hz» Large range actuation for initial alignment and drift compensation» Quiet actuation to correct for Earth tides and microseism at 0.15 Hz during
observation
HAM Chamber BSC Chamber
Raab: Status of Gravitational Wave Detectors
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Seismic Isolation – Springs and Masses
damped springcross section
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Core Optics Suspension and Control
Shadow sensors & voice-coil actuators provide
damping and control forces
Mirror is balanced on 30 microndiameter wire to 1/100th degree of arc
Optics suspended as simple pendulums
Raab: Status of Gravitational Wave Detectors
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Feedback & Control for Mirrors and Light
Damp suspended mirrors to vibration-isolated tables» 14 mirrors (pos, pit, yaw, side) = 56 loops
Damp mirror angles to lab floor using optical levers» 7 mirrors (pit, yaw) = 14 loops
Pre-stabilized laser» (frequency, intensity, pre-mode-cleaner) = 3 loops
Cavity length control» (mode-cleaner, common-mode frequency, common-arm, differential
arm, michelson, power-recycling) = 6 loops
Wave-front sensing/control» 7 mirrors (pit, yaw) = 14 loops
Beam-centering control» 2 arms (pit, yaw) = 4 loops
Raab: Status of Gravitational Wave Detectors
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Suspended Mirror Approximates a Free Mass Above Resonance
Data taken using shadow
sensors & voice coil actuators
Blue: suspended mirror XF
Cyan: free mass XF
Raab: Status of Gravitational Wave Detectors
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Despite a few difficulties, science runs started in 2002.
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LIGO Science Runs
S1: 17 days in Aug-Sep 2002» 3 LIGO interferometers in coincidence with GEO600 and ~2 days
with TAMA300
S2: Feb 14 – Apr 14, 2003» 3 LIGO interferometers in coincidence with TAMA300
S3: Oct 31, 2003 – Jan 9, 2004» 3 LIGO interferometers in coincidence with periods of operation of
TAMA300, GEO600 and Allegro
S4: Feb 22 – Mar 23, 2005» 3 LIGO interferometers in coincidence with GEO600, Allegro,
Auriga
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Binary Neutron Stars:S1 Range
Image: R. Powell
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Binary Neutron Stars:S2 Range
Image: R. Powell
S1 Range
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Interferometer Strain Sensitivity
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Science Analysis
Searches for periodic sources, such as neutron stars Searches for compact-binary inspirals, e.g., neutron
stars, black holes, MACHOs Searches for burst sources
» Waveforms may be unknown or poorly known
» Non-triggered search
» Triggered search(e.g., supernova or GRB triggers)
Stochastic waves of cosmological or astrophysical origin
Raab: Status of Gravitational Wave Detectors
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LIGO Search Papers(as of 9May05)
S1: “Setting upper limits on the strength of periodic gravitational waves using the first science data from the GEO600 and LIGO detectors”,Phys. Rev. D 69, 082004 (2004)
“First upper limits from LIGO on gravitational wave bursts”,Phys. Rev. D 69, 102001 (2004)
“Analysis of LIGO data for gravitational waves from binary neutron stars”, Phys. Rev. D 69, 122001 (2004)
“Analysis of first LIGO science data for stochastic gravitational waves”, Phys. Rev. D 69, 122004 (2004)
S2: “Limits on gravitational wave emission from selected pulsars using LIGO data”, Phys. Rev. Lett. 94, 181103 (2005).
“A search for gravitational waves associated with the gamma ray burst GRB030329 using the LIGO detectors”, gr-qc/0501068
“Upper limits on gravitational wave bursts from LIGO’s second science run”, gr-qc/0505029
Raab: Status of Gravitational Wave Detectors
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Binary Neutron Stars:Initial LIGO Target Range
Image: R. Powell
S2 Range
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Future Plans for Terrestrial Detectors
Improve reach of initial LIGO to run 1 integrated triple-coincidence year at design sensitivity
Virgo has made steady progress in commissioning, due to come on line in ~ 1 year
GEO600, TAMA300, striving for design sensitivity Resonant bars networking with interferometers for future runs Advanced LIGO technology under development, planning toward a
detector construction start for FY2008
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What’s next? Advanced LIGO…Major technological differences between LIGO and Advanced LIGO
Initial Interferometers
Advanced Interferometers
Open up wider band
ReshapeNoise
Quadruple pendulum:
Silica optics, welded to
silica suspension fibers
Advanced interferometry
Signal recycling
Active vibration isolation systems
High power laser (180W)
40kg
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Binary Neutron Stars:AdLIGO Range
Image: R. Powell
LIGO Range
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…and opening a new channel with a detector in space.
Planning underway for space-based detector, LISA, to open up a lower frequency band ~ 2013-ish
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Summary
We are currently experiencing a rapid advance in the sensitivity of searches for gravitational waves
Elements of world-wide networks of interferometers and bars are operating
The near future will see the confrontation of theory with many fine observational results