Max-Planck-Institut für Gravitationsphysik

(Albert-Einstein-Institut)Institut für Atom- und Molekülphysik

Detector Characterization of GEO 600 during the S4 science runS. Hild for the GEO 600 team

Introduction

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.

Typical sensitivity

Detector Characterization Tools

Lock-loss investigations

Data Quality

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

Instrumental duty cycle = 97.44 %

Longest lock > 52 hours

Instrumental duty cycle for locks longer than 10 hours = 72.25 %

Usually used for Burst analysis: lock segments > 300 seconds

Usually used for Inspiral analysis: lock segments > 2048 seconds

• 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

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).

Duty Cycle

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

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

Glitches @ 1 kHz

SeismoMon IFOMonHspecmon

Online h(t), with min/max per frequency bin Spectra of seismic (9 degrees of freedom) IFO channels potentially coupling to h(t)

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 @ 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

Windy conditions2 Volts = Saturation

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.

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

GEO REPORTS www.geo600.uni-hannover.de/georeports/

• Min/max spectrum of h(t)• 15 BLRMS of h(t)• Inspiral monitor• Spectrogram of h(t)

• Data quality • Chi2

• Calibration parameters

Bursts (HACRmon):

Lines (Linemon):

Sensitivity:

Calibration

• Time frequency distribution• SNR distribution• Duration• Bandwidth

• Line cataloguing • Harmonic identification• Sideband identification

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)

MU3-GlitchesWindy dayTractor activities

Chi2 cut

HACRmon

h(t) @ 1kHz

chi2

Example: MU3-Glitches(Problem was fixed during S4)

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Chi2: derived from calibration process

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