ligo-g020412-00-m ligo update ------------ “ the search for gravitational waves” barry barish...
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LIGO-G020412-00-M
LIGO Update------------
“The Search for Gravitational Waves”
Barry Barish
Caltech Trustees
10-Sept-02
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Laser Interferometer Gravitational-wave Observatory
Goals » First direct detection of gravitational waves
» Open new window on the universe – “gravitational wave astronomy”
NSF funded construction in 1994 for $296M» Caltech has fiduciary responsibility
» Joint Caltech/MIT technical and scientific team
» Construction completed in both Louisiana and Washington in 2000
Commissioning, Operations and Scientific Programs» First Interferometer “locked” – (Oct 2000)
» First coincidence running of both sites – (Dec 2001)
» First scientific data run “upper limits” – (Sept 2002)
» Search for gravitational waves – (2003 through 2006)
We propose to install “Advanced LIGO” in 2007» Cost ~ $125M total -- international collaboration
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LIGO Scientific Collaboration
Member Institutions
University of Adelaide ACIGA
Australian National University ACIGA
California State Dominquez Hills
Caltech LIGO
Caltech Experimental Gravitation CEGG
Caltech Theory CART
University of Cardiff GEO
Carleton College
Cornell University
University of Florida @ Gainesville
Glasgow University GEO
University of Hannover GEO
Harvard-Smithsonian
India-IUCAA
IAP Nizhny Novgorod
Iowa State University
Joint Institute of Laboratory Astrophysics
LIGO Livingston LIGOLA
LIGO Hanford LIGOWA
Louisiana State University
Louisiana Tech University
MIT LIGO
Max Planck (Garching) GEO
Max Planck (Potsdam) GEO
University of Michigan
Moscow State University
NAOJ - TAMA
University of Oregon
Pennsylvania State University Exp
Pennsylvania State University Theory
Southern University
Stanford University
University of Texas@Brownsville
University of Western Australia ACIGA
University of Wisconsin@Milwaukee
LSC Membership35 institutions > 350 collaborators
International India, Russia,
Germany, U.K, Japan
and Australia.
The international partners are
involved in all aspects of the LIGO research
program.
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Livingston Optical Telescopebroad outreach/education program
Telescope facts:
16 inch Richey Chretien telescope built by Optical Guidance Systems
Telescope provided by state funds via LSU. LIGO provides site and internet connection and incorporates telescope use into outreach program.
Internet accessible to facilitate classroom use
Proposed telescope location on fire access road gives clear view to south
Draft building concept utilizes surplus beam tube enclosures on raised footings with roll-off roof
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Budget LIGO Operations (2002 thru 2006)
Operations of LIGO funded beginning in 2002 for 5 years at a total funding of $160M
We function as one distributed laboratory (LIGO Laboratory) » Caltech (85 staff); MIT (25staff); Hanford (25 staff); Livingston (25 staff)
Advanced LIGO construction (not included) to be proposed next year
FY 2002
($M)
FY 2003
($M)
FY 2004
($M)
FY 2005
($M)
FY 2006
($M)
Operations $24 $29 $30 $30 $30
Advanced R&D
$4 $4 $3 $3 $3
+ $5M
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LIGO at Caltech Faculty
» Barish, Drever, Libbrecht, Prince and Weinstein (Exp) & Thorne(Th)
Scientists/Postdocs/Students» PhD theses; talented junior and senior scientists
LIGO Management» Directorate, Administration
LIGO Technical» Engineering center – precision engineering; controls; electronics
» 40 meter prototype; Optical laboratories, etc
LIGO Data Analysis and Computing» Simulations; Analysis infrastructure, Networking, Data Archive
» Scientific data analysis efforts
Source Simulations – Numerical Relativity
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Einstein’s Theory of Gravitationgravitational waves
• A necessary consequence of Special Relativity with its finite speed for information transfer
• Time dependent gravitational fields come from the acceleration of masses and propagate away from their sources as a space-time
warpage at the speed of light
Newton’s Theory“instantaneous action at a distance”Einstein’s Theoryinformation carried by gravitational radiation at the speed of light
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Direct Detectionastrophysical sources
Detectors in space
LISA
Gravitational Wave Astrophysical Source
Terrestrial detectors
LIGO, TAMA, Virgo,AIGO
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International network (LIGO, Virgo, GEO, TAMA, AIGO) of suspended mass Michelson-type interferometers on earth’s surface detect distant astrophysical sources
Interferometersterrestrial
suspended test masses
free massesfree masses
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Suspended Mass Interferometerthe concept
An interferometric gravitational wave detector
» A laser is used to measure the relative lengths of two orthogonal cavities (or arms)
As a wave passes, the arm lengths change
in different ways….
…causing the interference pattern
to change at the photodiode
• Arms in LIGO are 4km» Current technology then allows one
to measure h = L/L ~ 10-21 which turns out to be an interesting target
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How Small is 10-18 Meter?
Wavelength of light, about 1 micron100
One meter, about 40 inches
Human hair, about 100 microns000,10
LIGO sensitivity, 10-18 meter000,1
Nuclear diameter, 10-15 meter000,100
Atomic diameter, 10-10 meter000,10
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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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Noise Floor40 m prototype
• displacement sensitivityin 40 m prototype. • comparison to predicted contributions from various noise sources
sensitivity demonstration
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LIGOlong baseline interferometers (4 km)
Hanford Observatory
LivingstonObservatory
Laser Interferometer Gravitational-wave Observatory (LIGO)
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LIGO Livingston Observatory
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LIGO Hanford Observatory
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LIGObeam tube
LIGO beam tube under construction in January 1998
65 ft spiral welded sections
girth welded in portable clean room in the field
1.2 m diameter - 3mm stainless50 km of weld
NO LEAKS !!
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LIGOvacuum equipment
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Core Opticsfused silica
LIGO requirements Surface uniformity < 1 nm rms Scatter < 50 ppm Absorption < 2 ppm ROC matched < 3% Internal mode Q’s > 2 x 106
LIGO measurements• central 80 mm of 4ITM06 (Hanford 4K) • rms = 0.16 nm• optic far exceeds specification.
Surface figure = / 6000
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Core Optics installation and alignment
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Interferometerlocking
Laser
end test mass
Light bounces back and forth along arms about 150 times
input test massLight is “recycled” about 50 times
signal
Requires test masses to be held in position to 10-10-10-13 meter:“Locking the interferometer”
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Lock Acquisition
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LIGOwatching the interferometer lock
signal
LaserX Arm
Y Arm
Composite Video
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LIGOwatching the interferometer lock
signal
X Arm
Y Arm
Laser
X arm
Anti-symmetricport
Y arm
Reflected light
2 min
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An earthquake occurred, starting at UTC 17:38.
The plot shows the band limited rms output in counts over the 0.1- 0.3Hz band for four seismometer channels. We turned off lock acquisition and are waiting for the ground motion to calm down.
From electronic logbook 2-Jan-02
Engineering Rundetecting earthquakes
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17:03:03
01/02/2002
=========================================================================
Seismo-Watch
Earthquake Alert Bulletin No. 02-64441
=========================================================================
Preliminary data indicates a significant earthquake has occurred:
Regional Location: VANUATU ISLANDS
Magnitude: 7.3M
Greenwich Mean Date: 2002/01/02
Greenwich Mean Time: 17:22:50
Latitude: 17.78S
Longitude: 167.83E
Focal depth: 33.0km
Analysis Quality: A
Source: National Earthquake Information Center (USGS-NEIC)
Seismo-Watch, Your Source for Earthquake News and Information.
Visit http://www.seismo-watch.com
=========================================================================
All data are preliminary and subject to change.
Analysis Quality: A (good), B (fair), C (poor), D (bad)
Magnitude: Ml (local or Richter magnitude), Lg (mblg), Md (duration),
=========================================================================
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Detecting the Earth Tides Sun and Moon
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LIGO Goals and Priorities Interferometer performance
» Integrate commissioning and data taking consistent with obtaining one year of integrated data at h = 10-21 by end of 2006
Physics results from LIGO I» Initial upper limit results by early 2003
» First search results in 2004
» Reach LIGO I goals by 2007
Advanced LIGO» Prepare advanced LIGO proposal this fall
» International collaboration and broad LSC participation
» Advanced LIGO installation beginning by 2007
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Preliminary
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Astrophysical Sources the search for gravitational waves
Compact binary inspiral: “chirps”» NS-NS waveforms are well described» BH-BH need better waveforms » search technique: matched templates
Supernovae / GRBs: “bursts” » burst signals in coincidence with signals in
electromagnetic radiation » prompt alarm (~ one hour) with neutrino detectors
Pulsars in our galaxy: “periodic”» search for observed neutron stars (frequency,
doppler shift)» all sky search (computing challenge)» r-modes
Cosmological Signals“stochastic background”
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“Stochastic Background”cosmological signals
‘Murmurs’ from the Big Bangsignals from the early universe
Cosmic microwave background
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Stochastic Backgroundcoherence plot LHO 2K & LLO 4K
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Stochastic Backgroundprojected sensitivities
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Advanced LIGO
Active Seismic
Multiple Suspension
Saphire Optics
Higher Power Laser
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Advanced LIGO
Enhanced Systems
• improved laser• suspension• seismic isolation• test mass material
• narrow band optics
Improvement factor
~ 104
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Gravitational-wave Astronomyfrequency range
EM waves are studied over ~20 orders of magnitude» (ULF radio HE -rays)
Gravitational Waves over ~10 orders of magnitude
» (terrestrial + space)
Audio band
LIGO I (2003-06)Adv LIGO (2008 -)
LISA 2011-