1. Status of the LIGO Project
Rick Savage - LIGO Hanford Observatory
Future Trends in Cosmic Ray Physics ICRR – Kashiwa, Japan

2. Future Trends in Cosmic Ray Physics
Outline of Talk
LIGO Organization
LIGO Laboratory
LIGO Science Collaboration
Performance Goals
Initial LIGO
Advanced LIGO
Detector Installation
Detector Commissioning
Future Trends in Cosmic Ray Physics

3. Future Trends in Cosmic Ray Physics
LIGO Organization
Collaboration between California Institute of Technology (Caltech) and the Massachusetts Institute of Technology (MIT)
Funded by the National Science Foundation
LIGO Laboratory
Caltech, MIT, Hanford Observatory, Livingston Observatory
LIGO Scientific Collaboration
Twenty six member institutions
Commissioning of the initial detector
Data Analysis
Design of Advanced LIGO
Future Trends in Cosmic Ray Physics

4. Future Trends in Cosmic Ray Physics
LIGO Observatories 3 k m ( 1 s )
CALTECH
Pasadena
MIT
Boston
HANFORD
Washington
LIVINGSTON
Louisiana
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5. Future Trends in Cosmic Ray Physics
Hanford Observatory
4 km
2 km
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6. Livingston Observatory
4 km
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7. Global Network of GW Detectors
GEO
Virgo
LIGO
TAMA (LCGT)
AIGO
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8. Future Trends in Cosmic Ray Physics
GW Detectors …
AIGO
Australia
Virgo
Italy
GEO 600
Germany
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9. Future Trends in Cosmic Ray Physics
… GW Detectors
TAMA 300 Sensitivity – Best Ever!
TAMA 300
Japan
LCGT - Kamioka
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10. Event Localization with Array of Detectors
LIGO
Livingston
Hanford
TAMA
GEO
VIRGO
SOURCE
Dq ~ c dt / D12
Dq ~ 0.5 deg 1 2 q
DL = c dt
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11. Global Network – Joint Data Analysis
Protocols being established by GWIC (Gravitational Wave International Committee)
Commonality of data
Formats
Reduced data sets
Standards for software, validation techniques
Techniques to combine data from the elements of a network for different types of searches
Event lists (first pass)
Phase-coherent processing (second pass)
Shared computational resources and facilities
Concepts for a common publication policy
Concepts for establishing astronomical alerts
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12. Initial LIGO Interferometers
Power Recycled
Michelson
Interferometer
with Fabry-Perot
Arm Cavities
end test mass
4 km (2 km) Fabry-Perot arm cavity
recycling
mirror
input test mass
Laser
signal
beam splitter
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13. Initial LIGO Sensitivity Goal
Strain sensitivity
< 3x /Hz1/2 at 200 Hz
Displacement Noise
Seismic motion
Thermal Noise
Radiation Pressure
Sensing Noise
Photon Shot Noise
Residual Gas
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14. Future Trends in Cosmic Ray Physics
Advanced LIGO
Now being designed by the LIGO Scientific Collaboration
Goal:
Quantum-noise-limited interferometer
Factor of ten increase in sensitivity
Factor of 1000 in event rate. One day > entire 2-year initial data run
Schedule:
Begin installation: 2005
Begin data run: 2007
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15. Interferometer Concept
Signal recycling
180-watt laser
Sapphire test masses
Quadruple suspensions
Active seismic isolation
Active thermal correction
DC readout scheme?
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16. Future Trends in Cosmic Ray Physics
Design Sensitivity
h (1/ Hz1/2)
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17. Initial LIGO Detector Status
Construction project - Finished
Facilities, including beam tubes complete at both sites
Detector installation
Washington 2k interferometer complete
Livingston 4k interferometer complete
Washington 4k interferometer in progress
Interferometer commissioning
Just getting underway at Livingston
Washington 2k well under way
First astrophysical data run
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18. Future Trends in Cosmic Ray Physics
Beam Tubes
Type 304 SS
Special processing to reduce hydrogen outgassing
1.2 m diameter 3 mm thick
Spiral welded in 20 m lengths
Over 50 km of welds
NO LEAKS !
GPS alignment within 1 cm
LN2 and Ion pumps at 2 km intervals only
Serrated SS baffles to control scattered light
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19. Future Trends in Cosmic Ray Physics
Beam Tube Vacuum Bake
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20. Future Trends in Cosmic Ray Physics
Bake Results
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21. Future Trends in Cosmic Ray Physics
Vacuum Equipment
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22. Vibration Isolation Systems
Reduce in-band seismic motion by orders of magnitude
Compensate for microseism at 0.15 Hz by a factor of ten
Compensate (partially) for Earth tides
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23. Seismic Isolation – Springs and Masses
damped spring cross section
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24. Seismic System Performance
HAM stack
in air
102
100
10-2
10-4
10-6
10-8
10-10
Horizontal
Vertical
BSC stack in vacuum
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25. Future Trends in Cosmic Ray Physics
Core Optics
Surface uniformity < 1 nm rms
Scatter < 50 ppm
Absorption < 2 ppm
ROC matched < 3%
Internal mode Q’s > 2 x 106
Caltech data
CSIRO data
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26. Core Optics Suspension and Control
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27. Core Optics Installation and Alignment
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28. Future Trends in Cosmic Ray Physics
Pre-stabilized Laser
Deliver pre-stabilized laser light to the 15-m mode cleaner
Frequency fluctuations
In-band power fluctuations
Power fluctuations at 25 MHz
Provide actuator inputs for further stabilization
Wideband
Tidal 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
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29. Washington 2k Pre-stabilized Laser
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30. WA 2k Pre-stabilized Laser Performance
> 18,000 hours continuous operation
Frequency and PMC lock very robust
TEM00 power > 8 watts
Non-TEM00 power < 10%
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31. Interferometer Sensing and Control
Length Sensing and Control
Reflection locking technique length and frequency sensing
Control 4 longitudinal degrees of freedom and laser frequency
Requirements:
Differential arm length <10-13 m rms
Frequency noise < 3x10-7 Hz/Hz1/2 at 100 Hz
Controller noise for diff. arm length <10-20 m/ Hz1/2 at 150 Hz
Alignment sensing and control
Wavefront sensors (split photodetectors)
Digital Control of 12 mirror angles and the input beam direction
Requirement: angular fluctuations <10-8 rad rms
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32. Interferometer Optical Layout
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33. Control and Data Systems
Gravitational waves
Strain
Interferometer
Seisms
Common mode signals
Laser Fluctuations
Alignment signals
Thermal Noise
Acoustic signals
Electromagnetics
Seismometer signals
All interferometric detector projects have agreed on a standard data format
Anticipates joint data analysis
LIGO Frames for 1 interferometer are ~3MB/s
32 kB/s strain
~2 MB/s other interferometer signals
~1MB/s environmental sensors
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34. Detector Commissioning: 2-km Arm Test
12/99 – 3/00
Alignment “dead reckoning” worked
Digital controls, networks, and software all worked
Exercised fast analog laser frequency control
Verified that core optics meet specs
Long-term drifts consistent with earth tides
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35. Confirmation of Initial Alignment
beam spot
Opening gate valves revealed alignment “dead reckoned” from corner station was within 100 micro radians
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36. Future Trends in Cosmic Ray Physics
Locking the Long Arm
12/1/99 Flashes of light
12/9/ seconds lock
1/14/00 2 seconds lock
1/19/00 60 seconds lock
1/21/00 5 minutes lock (on other arm)
2/12/ minutes lock
3/4/00 90 minutes lock (temperature stabilized laser reference cavity)
3/26/00 10 hours lock
First interference fringes
from the 2-km arm
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37. Activation of Wavefront sensors
Alignment fluctuations before engaging wavefront sensors
After engaging wavefront sensors
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38. Long Arm Stretching Due to Earth Tides
10 hour locked section
Stretching consistent with earth tides
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39. Near-Michelson interferometer
Power-recycled
(short)Michelson
Interferometer
- Full mixed digital/analog servos
Interference fringes from the
pwr-recycled near-Michelson interferometer
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40. Locking the Complete Interferometer
Interferometer lock states
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41. Future Trends in Cosmic Ray Physics
Brief Locked Stretch
Y arm
X arm
Reflected
light
Anti-symmetric port
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42. End-to-End Modeling of Locking Process
Hanford 2k Model
Arm cavities
Anti-symmetric port
Modeled locking transient
Impulse applied to end mass
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43. Future Trends in Cosmic Ray Physics
Summary
Livingston Observatory
4-km interferometer installed commissioning underway
Hanford Observatory
2-km interferometer installed commissioning underway
4-km installation underway
2001
Commission Hanford 4-km interferometer
Engineering runs to improve strain sensitivity
First coincidence operation
Improve reliability and sensitivity
2002
Begin first astrophysics data run
Hanford Observatory control room
Future Trends in Cosmic Ray Physics