1. Barry Barish AIP Conference, Sydney Australia 11-July-02
LIGO Status and Plans
Barry Barish
AIP Conference, Sydney Australia
11-July-02

2. 2007
11-July-02
AIP Conference

3. A tour of LIGO

4. LIGO Sites Hanford Observatory Livingston Observatory 11-July-02
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5. LIGO Livingston Observatory
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6. LIGO Hanford Observatory
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7. Detection Strategy coincidences
Two Sites - Three Interferometers
Single Interferometer non-gaussian level ~50/hr
Hanford (Doubles) correlated rate (x1000) ~1/day
Hanford + Livingston uncorrelated (x5000) <0.1/yr
Data Recording (time series)
gravitational wave signal (0.2 MB/sec)
total data (16 MB/s)
on-line filters, diagnostics, data compression
off line data analysis, archive etc
Signal Extraction
signal from noise (vetoes, noise analysis)
templates, wavelets, etc
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8. The Beam Tube & Enclosure

9. LIGO Facilities beam tube enclosure
minimal enclosure
reinforced concrete
no services
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10. LIGO beam 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 stainless
50 km of weld
NO LEAKS !!
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AIP Conference

11. LIGO I the noise floor
Interferometry is limited by three fundamental noise sources
seismic noise at the lowest frequencies
thermal noise at intermediate frequencies
shot noise at high frequencies
Many other noise sources lurk underneath and must be controlled as the instrument is improved
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12. Beam Tube bakeout I = 2000 amps for ~ 1 month no leaks !!
final vacuum at level where it is not source of limiting noise (even future detectors)
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13. Vacuum Chambers

14. LIGO vacuum chambers
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15. Vacuum Chambers 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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16. Seismic Isolation

17. Seismic Isolation springs and masses
damped spring cross section
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18. Seismic Isolation constrained layer damped springs
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19. Seismic Isolation
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20. Optics & Suspensions

21. Core Optics fused 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
11-July-02
AIP Conference

22. Seismic Isolation suspension system
suspension assembly for a core optic
support structure is welded tubular stainless steel
suspension wire is 0.31 mm diameter steel music wire
fundamental violin mode frequency of 340 Hz
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23. Core Optics installation and alignment
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24. Laser & Mode Cleaner

25. LIGO laser Nd:YAG 1.064 mm Output power > 8W in TEM00 mode
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26. Laser stabilization IO PSL Interferometer 10-1 Hz/Hz1/2 10-4 Hz/ Hz1/2
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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27. Prestabilized Laser frequency noise
Simplification of beam path external to vacuum system eliminates peaks due to vibrations
Broadband noise better than spec in Hz region
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28. laboratory data vs e2e simulation
Pre-stabilized Laser
laboratory data vs e2e simulation
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29. Locking the Interferometers

30. Interferometer locking
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
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31. Lock Acquisition
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32. watching the interferometer lock
LIGO
watching the interferometer lock
Composite Video
Y Arm
Laser
X Arm
signal
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33. watching the interferometer lock
LIGO
watching the interferometer lock
Y arm
X arm
2 min
Y Arm
Reflected light
Anti-symmetric port
Laser
X Arm
signal
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34. E7 Engineering Run

35. LIGO Interferometers E7 sensitivities
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36. E7 Run Summary 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
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AIP Conference

37. detecting earthquakes
Engineering Run
detecting earthquakes
From electronic logbook 2-Jan-02
An earthquake occurred, starting at UTC 17:38.
The plot shows the band limited rms output in counts over the Hz band for four seismometer channels. We turned off lock acquisition and are waiting for the ground motion to calm down.
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AIP Conference

38. 17:03:03
01/02/2002
=========================================================================
Seismo-Watch
Earthquake Alert Bulletin No
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: E
Focal depth: 33.0km
Analysis Quality: A
Source: National Earthquake Information Center (USGS-NEIC)
Seismo-Watch, Your Source for Earthquake News and Information.
Visit
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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39. Detecting the Earth Tides Sun and Moon
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40. Run Plan commissioning & data taking
Science 1 run: 13 TB data “Upper Limits”
29 June - 15 July (delayed until >Aug 1 because of broken suspension wire)
2.5 weeks - comparable to E7
Target sensitivity: 200x design
Science 2 run: 44 TB data “Upper Limits”
22 November - 6 January 2003
8 weeks -- 15% of 1 yr
Target sensitivity: 20x design
Science 3 run: 142 TB data “Search Run”
1 July January 2004
26 weeks -- 50% of 1 yr
Target sensitivity: 5x design
11-July-02
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41. Commissioning Status for S1 Science Run
11-July-02
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42. LHO 2 km Interferometer Status
Locked in power recycled configuration
recycling factor up to 25, but typically ~15
Common mode servo implemented
Frequency stabilization from average arm length
Establishes control system “gain hierarchy”
5 W power into mode cleaner
Attenuators at photodiodes give effective input power mW
Tidal feedback operational
Lock duration up to 15 hours
DISPLACEMENT Sensitivity
Summer 2001
~ 3 x m/Hz1/2
December 2001 (E7)
~ 5 x m /Hz1/2 (~600 Hz)
Spring 2002
~ 2 x m /Hz1/2 (~350 Hz)
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43. Interferometer
sensitivity history
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44. LHO 4 km Interferometer status
In-vacuum installation completed last summer
Digital suspension controllers
Greater flexibility for tuning servos to improve reliability/noise
Permits frequency dependent orthogonalization of the displacement and angular control of the suspensions
Will be implemented on other interferometers after tests done
1 W power into mode cleaner
Attenuators at photodiodes give effective input power 20 mW
Locked in power recycled configuration
Recycling factor typically
Tidal feedback operational
Locks up to 4 hours
DISPLACEMENT Sensitivity ~2 x m/Hz1/2
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45. Interferometer
sensitivity history
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46. LLO 4 km Interferometer status
Power recycled configuration
1.9 W power input laser power into mode cleaner
Power recycling gain ~ 50
25-30 dB attenuation at dark port
Reasonably robust lock during night
Up to 4 hours
15 s – 3 min lock acquisition time
Tidal feedback operational
Wavefront alignment control operating on end mirrors
Microseismic feedforward reduces the dynamic range required from the controller (unique to LLO at present time)
PEPI reduces the seismic noise injected between 0.3 to 5 Hz at the end masses
DISPLACEMENT Sensitivity ~1.5 x Hz
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47. Interferometer
sensitivity history
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48. Astrophysical Sources signatures and data analysis
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”
11-July-02
AIP Conference

49. “Chirp Signal” binary inspiral
determine
distance from the earth r
masses of the two bodies
orbital eccentricity e and orbital inclination i
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50. Interferometer Data 40 m prototype
Real interferometer data is UGLY!!!
(Gliches - known and unknown)
LOCKING
NORMAL
RINGING
ROCKING
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51. The Problem
How much does real data degrade complicate the data analysis and degrade the sensitivity ??
Test with real data by setting an upper limit on galactic neutron star inspiral rate using 40 m data
11-July-02
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52. “Clean up” data stream
Effect of removing sinusoidal artifacts using multi-taper methods
Non stationary noise
Non gaussian tails
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53. Inspiral ‘Chirp’ Signal
Template Waveforms
“matched filtering”
687 filters
44.8 hrs of data
39.9 hrs arms locked
25.0 hrs good data
sensitivity to our galaxy
h ~ mHz-1/2
expected rate ~10-6/yr
11-July-02
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54. Optimal Signal Detection
Want to “lock-on” to one of a set of known signals
Requires:
source modeling
efficient algorithm
many computers
11-July-02
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55. Detection Efficiency
Simulated inspiral events provide end to end test of analysis and simulation code for reconstruction efficiency
Errors in distance measurements from presence of noise are consistent with SNR fluctuations
11-July-02
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56. Results from 40m Prototype
Loudest event used
to set upper-limit on
rate in our Galaxy:
R90% < 0.5 / hour
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57. Setting a limit
Upper limit on event rate can be determined from SNR of ‘loudest’ event
Limit on rate:
R < 0.5/hour with 90% CL
e = 0.33 = detection efficiency
An ideal detector would set a limit:
R < 0.16/hour
11-July-02
AIP Conference

58. Astrophysical Sources signatures and data analysis
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”
11-July-02
AIP Conference

59. “Burst Signal” supernova n’s light gravitational waves 11-July-02
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60. Supernovae gravitational waves Non axisymmetric collapse
‘burst’ signal
Rate
1/50 yr - our galaxy
3/yr - Virgo cluster
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61. Supernovae asymmetric collapse? pulsar proper motions Velocities -
young SNR(pulsars?)
> 500 km/sec
Burrows et al
recoil velocity of matter and neutrinos
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62. Supernovae signatures and sensitivity
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63. Astrophysical Sources signatures and data analysis
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”
11-July-02
AIP Conference

64. Periodic Signals spinning neutron stars
Isolated neutron stars with deformed crust
Newborn neutron stars with r-modes
X-ray binaries may be limited by gravitational waves
11-July-02
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65. “Periodic Signals” pulsars sensitivity
Pulsars in our galaxy
non axisymmetric:
10-4 < e < 10-6
science: neutron star precession; interiors
narrow band searches best
11-July-02
AIP Conference

66. Astrophysical Sources signatures and data analysis
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”
11-July-02
AIP Conference

67. “Stochastic Background”
cosmological signals
‘Murmurs’ from the Big Bang
signals from the early universe
Cosmic
microwave background
11-July-02
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68. 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
 
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69. Stochastic Background coherence plots LHO 2K & LHO 4K
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70. Stochastic Background coherence plot LHO 2K & LLO 4K
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71. Stochastic Background analysis in progress
Analytic calculation of expected upper limits (~50 hrs):
W ~2 x 105 for LLO-LHO 2k, W ~ 6 x 104 for LHO 2k-LHO 4k
Coherence measurements of GW channels show little coherence for LLO-LHO 2k correlations
Power line monitor coherence investigations suggest coherence should average out over course of the run
Plan to investigate effect of line removal on LHO 2k-LHO 4k correlations (e.g., reduction in correlated noise, etc.)
Plan to inject simulated stochastic signals into the data and extract from the noise
Plan to also correlate LLO with ALLEGRO bar detector
ALLEGRO was rotated into 3 different positions during E7
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72. Stochastic Background projected sensitivities
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73. LIGO conclusions 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
Significant improvements in sensitivity anticipated to begin about 2006
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74. Finis

75. Planned Detector Modifications active external seismic
BSC
HAM
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76. Advanced Detector R&D and Advanced LIGO

77. Advanced LIGO R&D Status
Working toward construction proposal to Fall 2002
“bottoms-up” costing has nearly been completed
Plan assumes construction funding available 1Q2005
some long lead funds in 1Q2004
Supports an installation start of 4Q2006
Soon ready to confront scope decisions (number of interferometers, trimming features to control costs, etc.)
Advanced R&D program is proceeding well
GEO and ACIGA teams forming strong international partnership
11-July-02
AIP Conference

78. Advanced LIGO R&D Status
Interferometer Sensing & Control (ISC):
GEO 10m “proof of concept” experiment:
Preparation proceeding well
Results available for 40m Program in early 2003 (lock acquisition experience, sensing matrix selection, etc.)
40m Lab for Precision Controls Testing:
Infrastructure has been completed (i.e. PSL, vacuum controls & envelope, Data Acquisition system, etc.)
Working on the installation of the 12m input MC optics and suspensions, and suspension controllers by 3Q02
Gingin facility for High Power Testing:
Within the next year the LIGO Lab will deliver two characterized sapphire test masses and a prototype thermal compensation system (beam scan and/or ring heater)
The facility development is advancing nicely
Activities closely linked with subsystem, LASTI R&D plan
11-July-02
AIP Conference

79. Advanced LIGO R&D Status
Seismic Isolation system (SEI):
Development of pre-isolation system accelerated for use in retrofit on initial LIGO
hydraulic & electro-magnet actuation variants
To be tested at the LASTI facility
“Technology Demonstrator” system has been fabricated
a two stage, 12 degree of freedom active, stiff, isolation system
being installed into the Stanford Engineering Test Facility (ETF)
LASTI infrastructure has been completed (including BSC stack to support pre-isolation full scale testing for initial LIGO)
11-July-02
AIP Conference

80. Advanced LIGO R&D Status
Suspension System (SUS):
Complete fused-quartz fiber suspensions functioning in the GEO-600 interferometer
Progress, in theory and in experiment, on both circular fibers (tapered) and ribbons
Dynamics testing is underway on a quadruple pendulum prototype
Silica-sapphire hydroxy-catalysis bonding looks feasible; silica-leadglass to be explored
Significant design work underway for ‘triple’ suspensions
TNI nearing final results for fused silica; sapphire mirrors ready in Fall 2002 for next phase
11-July-02
AIP Conference

81. Advanced LIGO R&D Status
Core Optics Components (COC):
New optical homogeneity measurements along the ‘a’ crystal axis are close to acceptable (13nm RMS over 80mm path length)
Tests to compensate for optical inhomogeneity if required, look promising (computer controlled ‘spot’ polishing and ion beam etching)
Recent sapphire annealing efforts are encouraging (reductions to 20 ppm/cm vs a requirement of 10 ppm/cm)
Coatings on large optics show sub-ppm losses (SMA/Mackowski)
Coating mechanical loss program in full swing; materials rather than interfaces seem to be the culprit
11-July-02
AIP Conference