1. LIGO Present and Future
Barry Barish
Directory of the LIGO Laboratory

2. LIGO I Schedule and Plan
LIGO I has been built by LIGO Lab (Caltech & MIT)
1996 Construction Underway (mostly civil)
1997 Facility Construction (vacuum system)
1998 Interferometer Construction (complete facilities)
1999 Construction Complete (interferometers in vacuum)
2000 Detector Installation (commissioning subsystems)
2001 Commission Interferometers (first coincidences)
2002 Sensitivity studies (initiate LIGO I Science Run)
LIGO I data run (one year integrated data at h ~ 10-21)
2006+ Begin ‘Advanced LIGO’ installation

3. LIGO Scientific Collaboration
March 02
LIGO Scientific Collaboration
LSC Institutional Membership
35 institutions > 350 collaborators
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 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
University of Western Australia ACIGA
University of
International
India, Russia,
Germany,
U.K, Japan
and
Australia.
The international partners are involved in all aspects of the LIGO research program.

4. LIGO Sites
Hanford
Observatory
Livingston
Observatory

5. LIGO Livingston Observatory

6. LIGO Hanford Observatory

7. Coincidences between the LIGO Sites
Two Sites – Three interferometers
Single interferometer non-gaussian level ~50/hour
Local coincidence - Hanford 2K and 4K (÷~1000) ~1/day
Hanford/Livingston coincidence (uncorrelated) <0.1/yr
GEO coincidence further reduces the false signal rate
Data (continuous time-frequency record)
Gravitational wave signal 0.2MB/sec
Total data recorded MB/sec
Gravitational Wave Signal Extraction
Signal from noise (noise analysis, vetoes, coincidences, etc

8. LIGO Facility Noise Levels
Fundamental Noise Sources
Seismic at low frequencies
Thermal at mid frequencies
Shot at high frequencies
Facility Noise Sources (example)
Residual Gas
10-6 torr H2 unbaked
10-9 torr H2 baked

9. Beam Pipe and Enclosure
Minimal Enclosure (no services)
Beam Pipe
1.2m diam; 3 mm stainless
65 ft spiral weld sections
50 km of weld (NO LEAKS!)

10. Baking out the LIGO Beam Pipe
insulation
~ 2000 amps for one month
Fermilab Magnet Power Supply

11. Vacuum Chambers and Seismic Isolation
constrained layer damped springs
Vacuum Chambers
Vacuum Chamber
Gate Valve
passive isolation

12. LIGO I Suspension and Optics
fused silica
Single suspension 0.31mm music wire
Surface figure = / 6000
surface uniformity < 1nm rms
scatter < 50 ppm
absorption < 2 ppm
internal Q’s > 2 106

13. Commissioning the LIGO I Subsystems
stablization IO
10-Watt
Laser
PSL
Interferometer
15m
4 km
Tidal
Wideband
10-1 Hz/Hz1/2
10-4 Hz/Hz1/2
10-7 Hz/Hz1/2
Nd:Yag mm
Output power
>8 Watt
TEM00 mode
LIGO I
Goal

14. LIGO Prestablized Laser Data vs Simulation

15. LIGO I Interferometer Configuration
end test mass
Requires test masses to
be held in position to
meter:
“Locking the interferometer”
Light bounces back and forth along arms about 150 times
Light is “recycled” about 50 times
input test mass
Laser
signal

16. Locking the LIGO I Interferometers
One meter, about 40 inches
Earthtides, about 100 microns
Human hair, about 100 microns
Microseismic motion, about 1 micron
Wavelength of light, about 1 micron
Precision required to lock, about meter
Atomic diameter, meter
Nuclear diameter, meter
LIGO sensitivity, meter

17. Watching LIGO Lock
Composite Video
Y Arm
Laser
X Arm
signal

18. Watching an ‘Early’ Lock
Y arm
X arm
2 min
Y Arm
Reflected light
Anti-symmetric port
Laser
X Arm
signal

19. Dynamical Control Model
Lock Acquisition
LIGO I
Dynamical Control Model by
Matt Evans
Caltech

20. LIGO Engineering Run (E7) Sensitivities
Final LIGO
Milestone
“Coincidences
Between the
Sites in 2001”
Engineering
Run
28 Dec 01 to
14 Jan 02

21. LIGO + GEO Interferometers
28 Dec Jan 2002 (402 hr)
Coincidence Data
All segments Segments >15min
2X: H2, L1
locked hrs (39%) hrs (24%)
clean hrs (26%) hrs (16%)
H2,L1 longest clean segment: 1:50
3X : L1+H1+ H2
locked hrs (35%) hrs (18%)
clean hrs (21%) hrs (11%)
L1+H1+ H2 : longest clean segment: 1:18
4X: L1+H1+ H2 +GEO:
77 hrs (23 %) hrs (7.81 %)
5X: ALLEGRO + …
Singles data
All segments Segments >15min
L1 locked hrs (71%) hrs (62%)
L1 clean hrs (61%) hrs (53%)
L1 longest clean segment: 3:58
H1 locked hrs (72%) hrs (57%)
H1 clean hrs (62%) hrs (48%)
H1 longest clean segment: 4:04
H2 locked hrs (53%) hrs (39%)
H2 clean hrs (38%) hrs (28%)
H2 longest clean segment: 7:24
Conclusion: Large Duty Cycle Looks Attainable

22. LIGO Sensitivity History
Hanford 2K
Livingston 4K 06-02

23. LIGO I Astrophysical Sources Search Efforts
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”

24. Stochastic Background Sensitivity
Detection
Cross correlate Hanford and Livingston Interferometers
Good Sensitivity
GW wavelength  2x detector baseline f  40 Hz
Initial LIGO Sensitivity   10-5
Advanced LIGO Sensitivity  

25. Stochastic Background Coherence Plots

26. Stochastic Background Sensitivities

27. LIGO I Status and Plans LIGO construction complete
LIGO commissioning and testing ‘on track’
Engineering test runs underway, during period when emphasis is on commissioning, detector sensitivity and reliability. (Short upper limit data runs interleaved)
First Science Search Run : first search run will begin during 2003; goal is to obtain and analyze one year of integrated data at h ~ by 2006
Significant improvements in sensitivity anticipated to begin about 2006

28. Advanced LIGO Status and Plans
GEO, ACIGA and LIGO form a very strong international partnership to develop and manage Advanced LIGO
Working toward NSF construction proposal to be submitted in Fall 2002
Advanced R&D program is proceeding well
Baseline design and installation scenarios established (alternative carried)
“Bottoms-up” costing has nearly been completed
Plan assumes long lead funds available in 2004; major construction funds in 2005
Supports an installation by 2007