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LIGO-G000314-00-M First Generation Interferometers Barry Barish 30 Oct 2000 Workshop on Astrophysical Sources for Ground-Based Gravitational Wave Detectors.

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Presentation on theme: "LIGO-G000314-00-M First Generation Interferometers Barry Barish 30 Oct 2000 Workshop on Astrophysical Sources for Ground-Based Gravitational Wave Detectors."— Presentation transcript:

1 LIGO-G M First Generation Interferometers Barry Barish 30 Oct 2000 Workshop on Astrophysical Sources for Ground-Based Gravitational Wave Detectors Drexel University

2 LIGO-G M Detection of Gravitational Waves precision optical instrument detect a stretch (squash) of m !! ( a small fraction of the size of a proton) first generation interferometers will have strain sensitivity h ~ for 10Hz < f < 10KHz time frame , then upgrades to improve sensitivity (Fritschel) LIGO interferometer

3 LIGO-G M Interferometers 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 Sensitive region

4 LIGO-G M Interferomers international network LIGO Simultaneously detect signal (within msec) detection confidence locate the sources decompose the polarization of gravitational waves GEO Virgo TAMA AIGO

5 LIGO-G M LIGO (Washington)LIGO (Louisiana) Interferometers international network

6 LIGO-G M GEO 600 (Germany)Virgo (Italy) Interferometers international network

7 LIGO-G M TAMA 300 (Japan) AIGO (Australia) Interferometers international network

8 LIGO-G M Interferometers 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 Sensitive region shot

9 LIGO-G M Phase Noise splitting the fringe spectral sensitivity of MIT phase noise interferometer above 500 Hz shot noise limited near LIGO I goal additional features are from 60 Hz powerline harmonics, wire resonances (600 Hz), mount resonances, etc shot noise

10 LIGO-G M Noise Floor 40 m prototype displacement sensitivity in 40 m prototype. comparison to predicted contributions from various noise sources

11 LIGO-G M Noise Floor TAMA 300

12 LIGO-G M Interferometers 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 Sensitive region vacuum

13 LIGO-G M Vacuum Systems beam tube enclosures LIGO minimal enclosures no services Virgo preparing arms GEO tube in the trench

14 LIGO-G M Beam Tubes LIGO 4 km beam tube (1998) TAMA 300 m beam pipe

15 LIGO-G M Beam Tube Bakeout LIGO bakeout standard quantum limit phase noise residual gas

16 LIGO-G M Vacuum Chambers test masses, optics TAMA chambers LIGO chambers

17 LIGO-G M Interferometers 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 Sensitive region seismic

18 LIGO-G M Suspension vertical transfer function measured and simulated (prototype) Seismic Isolation Virgo “Long Suspensions” inverted pendulum five intermediate filters

19 LIGO-G M Long Suspensions Virgo installation at the site Beam Splitter and North Input mirror All four long suspensions for the entire central interferometer

20 LIGO-G M Suspensions GEO triple pendulum

21 LIGO-G M Test Masses fibers and bonding - GEO

22 LIGO-G M Interferometers basic optical configuration

23 LIGO-G M Optics mirrors, coating and polishing  All optics polished & coated »Microroughness within spec. (<10 ppm scatter) »Radius of curvature within spec.  R/R  5%) »Coating defects within spec. (pt. defects < 2 ppm, 10 optics tested) »Coating absorption within spec. (<1 ppm, 40 optics tested) LIGO

24 LIGO-G M LIGO metrology  Caltech  CSIRO

25 LIGO-G M Interferometers lasers  Nd:YAG (1.064  m)  Output power > 8W in TEM00 mode GEO Laser LIGO Laser master oscillator power amplifier Master-Slave configuration with 12W output power Virgo Laser residual frequency noise

26 LIGO-G M Prestabalized Laser performance  > 18,000 hours continuous operation  Frequency and lock very robust  TEM 00 power > 8 watts  Non-TEM 00 power < 10%

27 LIGO-G M Interferometers sensitivity curves TAMA 300 GEO 600 Virgo LIGO

28 LIGO-G M Interferometers testing and commissioning  TAMA 300 »interferometer locked; noise/robustness improved; successful two week data run (Aug 00)  LIGO »subsystems commissioned; »2 km first lock (Nov 00)  Geo 600 »commissioning tests  Virgo »testing isolation systems; commissioning input optics  AIGO »setting up central facility; short arm interferometer

29 LIGO-G M TAMA Performance noise source analysis

30 LIGO-G M TAMA Performance noise source analysis

31 LIGO-G M best sensitivity: 5x Hz -1/2 (~ 1kHz) interferometer stability; longest lock > 12 hrs non-stationary noise significantly reduced auxiliary signals approx 100 signals including feedback and error signals and environmental signals were recorded plans two-month data run planned for Jan 2001; signal recycling added next year. TAMA 2 week data run 21 Aug to 4 Sept 00

32 LIGO-G M LIGO commissioning  Mode cleaner and Pre-Stabilized Laser  2km one-arm cavity  short Michelson interferometer studies  Lock entire Michelson Fabry-Perot interferometer “FIRST LOCK”

33 LIGO-G M 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

34 LIGO-G M LIGO locking a 2km 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)  2/12/00 18 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

35 LIGO-G M 2km Fabry-Perot cavity 15 minute locked stretch

36 LIGO-G M Near-Michelson interferometer Interference fringes from the power recycled near Michelson interferometer power recycled (short) Michelson Interferometer employs full mixed digital/analog servos

37 LIGO-G M LIGO first lock signal Laser X Arm Y Arm Composite Video

38 LIGO-G M LIGO brief locked stretch X arm Reflected light Y arm Anti-symmetric port 2 min

39 LIGO-G M Interferometer 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

40 LIGO-G M Interferometer Data 40 m Real interferometer data is UGLY!!! (Gliches - known and unknown) LOCKING RINGING NORMAL ROCKING

41 LIGO-G M “Clean up” data stream Effect of removing sinusoidal artifacts using multi-taper methods Non stationary noise Non gaussian tails

42 LIGO-G M 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

43 LIGO-G M 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

44 LIGO-G M 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  = 0.33 = detection efficiency An ideal detector would set a limit: R < 0.16/hour

45 LIGO-G M TAMA 300 search for binary coalescence 2-step hierarchical method chirp masses (0.3-10)M 0 strain calibrated  h/h ~ 1 % Matched templates

46 LIGO-G M TAMA 300 preliminary result For signal/noise = 7.2 Expect: 2.5 events Observe: 2 events Note: for a 1.4 M 0 NS-NS inspiral this limit corresponds to a max distance = 6.2 kpc Rate < 0.59 ev/hr 90% C.L.

47 LIGO-G M Conclusions  First generation long baseline suspended mass interferometers are being completed with h ~  commissioning, testing and characterization of the interferometers is underway  data analysis schemes are being developed, including tests with real data from the 40 m prototype and TAMA  science data taking to begin soon – TAMA ; then LIGO (2002)  plans and agreements being made for exchange of data for coincidences between detectors (GWIC)  Second generation - significant improvements in sensitivity (h ~ ) are anticipated about 2007+


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