Status of GEO600

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Status of GEO600

• Benno Willke
• for the GEO600 team

ESF Exploratory Workshop Perugia, September 2005
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container cluster 2005
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Tube / Trench
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Clean Room / Control Room
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Triple Pendulum Suspension
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Thermal Noise / Monolithic Suspension
Weld
Silicate (Hydroxy- Catalysis) Bonding
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reaction pendulum
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GEO 600 optical layout
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Dual Recycling Length Control
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Michelson length control
lt 0.1Hz
lt 10 Hz

• Reaction Pendulum
• 3 coil-magnet actuators at intermediate
  mass, range 100µm
• Electrostatic actuation on test mass bias
  630V, range 0-900V 3.5µm

gt 10 Hz
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Alignment Control
Alignment Control
4 degrees of freedom at MC 1
4 at MC 2
4 at MI (common mode)
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differential wave-front sensing
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GEO 600 design sensitivity
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Evolution of the GEO 600 Sensitivity
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GEO600 Duty Cycle
date run name duty cycle longest lock
Jan 2002 E7 75 3h 40min
Aug 2002 S1 98 121h
Nov 2003 Jan 2004 S3-I (7days)S3-II(14 days) 95 98 95h
Aug 2004 Jan 2005 over night runs (51 days) 94
Mar 2005 S4 97 52h
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S4

• Feb 22nd March 23rd, 708 hours
• Two manned shifts/day (5-21 UTC), 1
  Expert-On-Duty 8-8UTC
• Fully automated overnight shifts SMS alarms to
  E-O-D
• Locking status
• DAQS (DCUs running, frame making, timing,
  calibration)
• Temperatures
• Vacuum
• Instrumental duty cycle 97.5, 95 w/o noisy
  period, 72gt10h
• Longest lock 52h

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detector characterization

• Sensitivity
• Min/max spectrum of h(t)
• 15 BLRMS of h(t)
• Inspiral monitor
• Spectrogram of h(t)
• Calibration
• Data quality
• Chi2
• Calibration parameters

• Bursts (HACRmon)
• Time frequency distribution
• SNR distribution
• Duration
• Bandwidth
• Lines (Linemon)
• Line cataloguing
• Harmonic identification
• Sideband identification

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Typical S4 Sensitivity

• h(t)
• derived from two quadratures of MI diff. EP
• diff. calibration estimation of optical gain
  MID loop gain (for online calibration)
• noise proj.
• calibration lines for various online noise
  projections
• violin mode
• fiber modes from the monolithic suspension stage
• MC turbo turbo pump frequency (822 Hz)
• Mains 50 Hz and multiples from mains

• h(t)
• derived from two quadratures of MI diff. EP
• diff. calibration estimation of optical gain
  MID loop gain (for online calibration)
• noise proj.
• calibration lines for various online noise
  projections
• violin mode
• fiber modes from the monolithic suspension stage
• MC turbo turbo pump frequency (822 Hz)
• Mains 50 Hz and multiples from mains

• h(t)
• derived from two quadratures of MI diff. EP
• diff. calibration estimation of optical gain
  MID loop gain (for online calibration)
• noise proj.
• calibration lines for various online noise
  projections
• violin mode
• fiber modes from the monolithic suspension stage
• MC turbo turbo pump frequency (822 Hz)
• Mains 50 Hz and multiples from mains

• h(t)
• derived from two quadratures of MI diff. EP
• diff. calibration estimation of optical gain
  MID loop gain (for online calibration)
• noise proj.
• calibration lines for various online noise
  projections
• violin mode
• fiber modes from the monolithic suspension stage
• MC turbo turbo pump frequency (822 Hz)
• Mains 50 Hz and multiples from mains

• h(t)
• derived from two quadratures of MI diff. EP
• diff. calibration estimation of optical gain
  MID loop gain (for online calibration)
• noise proj.
• calibration lines for various online noise
  projections
• violin mode
• fiber modes from the monolithic suspension stage
• MC turbo turbo pump frequency (822 Hz)
• Mains 50 Hz and multiples from mains

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Calibration
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On-line optical TF measurements
P and Q
CAL
actuator
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Calibration
?
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Photon Pressure Calibrator
Wavelength 1035 nm _at_ 20C Max. power 1.4 W,
FWHM 0.66nm
Good agreement with ESD calibration
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Optical Gain
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Calibrated EP Quadrature Signals
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Combining hP(t) and hQ(t) results
h 1/sqrt(Hz)

• Get the best of hP and hQ plus a little extra!

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increase of power recycling factor
Michelson Interferometer
Mode Cleaners
Laser
T0.09
Power Recycling Cavity Mode
matching gt85 Finesse 8300 Linewidth
30 Hz

Output Mode Cleaner
4/0.091.6 7000
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Thermal lensing in BSoutput mode pattern (PRMI)
A few minutes after relocking f 8km ? a0.3 /-
0.05ppm/cm
Directly after relocking f20km
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GEO 600 design sensitivity
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Tuning signal recycling to 300 Hz

• lock acquisition at 5kHz
• tuning needs to adjust of 6 parameters (look-up
  table)
• improved input file for simulations and how to
  transfer results to experiment
• achieved downtuning to 200Hz
• MI AA instability could be fixed

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Interferometer Readout - Sidebands
mirror
phasemodualtor
laser
beam splitter
mirror
photodetector
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Schnupp Modulation
mirror
phasemodualtor
laser
beam splitter
mirror
photodetector
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Gravitational Wave Side Bands
mirror
phasemodualtor
laser
beam splitter
mirror
photodetector
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Detuned Signal Recycling
mirror
phasemodualtor
laser
beam splitter
mirror
photodetector
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Unbalanced Sidebands
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Signal Recycling digital

• digital loop allows for steep filter
• noise contribution reduced by up to a factor of
  200

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Sqrt circuits in MI loop
ESD F ? U2 Sqrt circuits are necessary to give
full linear force range for acquisition. Drawback
sqrt circuits are noisy 1µV/sqrt(Hz) (100µV/sqr
t(Hz) _at_ ESD)
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MI loop whitening / dewhitening
Whitening right after mixer zero 3.5 Hz pole 35
Hz Dewhitening for both split passes Passive
dewhit-ening done in HV path (0-1kV)
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sensitivity improvements since July
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Evolution of the GEO 600 Sensitivity
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Current vs. Design sensitivity
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Non-stationary Noise
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Near Future

• finish commissioning
• increase circulating power
• find source of optical losses in PR cavity
• increase MI loop gain between 1-10 Hz
• improve RF circuitry
• optimize stability
• join S5 in overnight/weekend mode until
  commissioning is finished
• fully join S5

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