1. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Title Hot topic: 1 kHz Glitches in S4 Max-Planck-Institut für Gravitationsphysik (Albert-Einstein-Institut) Introduction Stefan Hild Ilias WG1 meeting, Hannover, April 2005

2. GEO‘s sensitivity for last 20 days of S4 Peak sensitivity ‚drifted‘ during S4 (much more than at other frequencies)

3. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 BLRMS of H(t) vs glitch rate H(t) BLRMS 990-1000 Hz Glitchrate 700-2000 Hz Found relation between glitchrate and peak sensitivity.

4. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Spectra for good and bad time Example times: high glitch rate 2005-03-22 06:10:00 low glitch rate 2005-03-22 13:00:00 Glitches cause additional noise between 400 Hz and 1.3 kHz

5. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Spectrograms of differential EP-P High glitchrate Low glitchrate

6. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Gliches vs BLRMS @ 1 kHz

7. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Timedomain distribution

8. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Noise projections 1 kHz glitches can‘t be explained by our current set of noiseprojections

9. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 HACR: Burst and glitch analysis Take in 32 seconds of data Subdevide this into subsegments of 32 ms (Overlab of 28 ms) Windowing and FFT Spectrogram (2-dim set of numbers / pixels) Clustering Triggers = mean = standard deviation = high threshold = 25 = low threshold = 5 Index i = subsegment Index k = frequency bin

10. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 SNR distribution

11. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Number of pixels

12. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Duration of bursts

13. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Bandwidth of burst Probably maximal bandwidth is limited to 400 Hz (strong lines 822 and 1266 Hz)

14. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Time-delay between glitches

15. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 Periodicity of the glitches Sometimes one can see a periodicity (5-10 times per hour) of the glitchrate

16. Stefan Hild Ilias WG1 meeting, Hannover, April 2005 How to attack the problem „Thinking“: Which hardware of GEO600 could cause glitches with these properties ? Coupling ? What experiments do we need to check a potential hypothesis? Data analysis: Try to find a correlation between glitchrate during S4 and ??? Compare detector status for good (low glitch rate) and bad time (high glitch rate). Anything different ? Maybe the periodicity leads us to origin of the glitches ?