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Detector Characterization of GEO 600 during the
S4 science run
S. Hild for the GEO 600 team
Introduction

Glitches _at_ 1 kHz

• GEO 600 participated in the LSC S4 science run,
  which took place between February 22nd and March
  24th 2005.
• During these 708 hours a duty cycle in nominal
  science mode of 96.6 was achieved.
• Many monitors for detector characterization were
  developed and used for commissioning before S4 as
  well as for online detector characterization
  during the science run.

Strain RMS
Glitchrate (HACRmon)
Typical sensitivity
Found a perfect correlation between BLRMS (989 to
999 Hz) of h(t) and the rate of glitches with a
central frequency between 700 and 2000 Hz.

• 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

Strain RMS

• Some properties of the glitches (derived from
  HACRmon)
• glitches cause excess noise between
• 400 and 1300 Hz
• average duration of about 20 ms
• average bandwidth of about 200 Hz
• Glitch rate varies from nearly 0 to 4000
• glitches per 15 minutes

Glitchrate (HACRmon)
Windy conditions

• There was one stormy day in S4
• Wind shakes the walls of the buildings
• ? causes acoustic noise inside
• the buildings
• ? movement of walls couples
• via foundation to vacuum system
• Large misalignment (Michelson auto-alignment is
  gain limited _at_ pendulum resonance frequencies)
• Non-optimal spatial overlap of beams at the
  beamsplitter
• Increased light level at the dark port and on
  detection photodiode
• Saturation of MI diff EP in electronics

2 Volts Saturation
Voltage V
The signal recycling mirror was tuned for a peak
response at 1 kHz. Sensitivity corresponds to
range of about 0.4 MPc for BH-BH inspirals (about
0.25 MPc for BH-NS and NS-NS).
a.u.
Duty Cycle
m/s
a.u.
Instrumental duty cycle 97.44 Longest lock
gt 52 hours Instrumental duty cycle for locks
longer than 10 hours 72.25 Usually used for
Burst analysis lock segments gt 300
seconds Usually used for Inspiral analysis lock
segments gt 2048 seconds
a.u.
Data Quality
HACRmon
MU3-Glitches Windy day Tractor activities
h(t) _at_ 1kHz
Chi2 cut
Chi2 derived from calibration process

• Data Quality Flags
• 1. Chi2
• Derived from calibration process (compares model
  and measurement of the optical gain at
  calibration line frequencies)
• Used to flag MU3-Glitches
• 2. Saturation of detection signal
• Used to flag bad times due to stormy weather
• 3. Seismic flag (planned)
• Flag for high level of local seismic noise
  (tractors passing buildings)

Lock-loss investigations
chi2

• Every loss of lock during S4 was analysed !
• Signals used for lock-loss investigations
• Logitudinal error points and feedback points of
  modecleaners, Power Recycling, Signal Recycling
  and differential Michelson. (whitened and
  unwhitened signals)
• Autoalignment error points and feedback points of
  modecleaners, Power Recycling, Signal Recycling
  and differential Michelson.
• Laser power stabilisation loop
• Light powers at various points of the
  interferometer
• Environmental monitors
• For future
• Monitoring of important RF-modulation signals

Reason for lockloss quantity
Tractor passing east or north building 35
High frequency glitches in power-stab loop 25
Maintenance 22
2.5 Hz oscillation in MID-AA-Tilt 16
Stormy weather 14
Earthquakes 5
12 Hz oscillation in MID-long-loop 5
Coupled ringing in SR-AA and MID-long 3
Modecleaner 1 oscillation 30 Hz 2
Horse galloping along north building 2
End of range 1
Unlear 4
Total 134
Example MU3-Glitches
(Problem was fixed during S4)
Detector Characterization Tools

IFOMon
Hspecmon
SeismoMon
Spectra of seismic (9 degrees of freedom)
Online h(t), with min/max per frequency bin
IFO channels potentially coupling to h(t)
GEO REPORTS www.geo600.uni-hannover.de/georeports
/
Bursts (HACRmon) Lines (Linemon)
Sensitivity Calibration

• Time frequency distribution
• SNR distribution
• Duration
• Bandwidth
• Line cataloguing
• Harmonic identification
• Sideband identification

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

Exemplary lock loss investigation 2.5 Hz
oscillation MID-AA-Tilt