1. Very brief update on the GEO mystery noise investigations
Stefan Hild
for the GEO600 team
15th ILIAS WG1 meeting, March 2008, Cascina

2. Photographs by A. Freise
Introduction
Just a quick update: following up the mystery noise session + brainstorming at last ILIAS meeting.
See: for further detail…
Photographs by A. Freise
Stefan Hild
ILIAS WG1, March 2008

3. How to tackle the mystery noise ?
Stefan Hild
ILIAS WG1, March 2008

4. How to tackle the mystery noise ?
Displacement noise
Yes / No ?
Characteristics of
the mystery noise
Any clues from the observation? Displacement-like or not? Stationary? Related to glitches? ....
Stefan Hild
ILIAS WG1, March 2008

5. How to tackle the mystery noise ?
Fundamental
noises
Mystery
noise
Projected
noises
Displacement noise
Yes / No ?
Characteristics of
the mystery noise
Is the gap real? All projections correct? Are all noises projected? Calculations of fundamental noises correct?
Stefan Hild
ILIAS WG1, March 2008

6. How to tackle the mystery noise ?
Upconversion
Fundamental
noises
Scattered light
Mystery
noise
Projected
noises
Exotic noises
Displacement noise
Yes / No ?
Characteristics of
the mystery noise
Can we rule out the usual candidates: non-linearly coupling noises? How about exotic noises ? ....
Stefan Hild
ILIAS WG1, March 2008

7. Stefan Hild
ILIAS WG1, March 2008

8. The gap looks smaller at low power, but …
Low vs high power
Nominal power
low power
The gap looks smaller at low power, but …
Stefan Hild
ILIAS WG1, March 2008

9. … but the mystery stays roughly the same
Low vs high power
… but the mystery stays roughly the same
Stefan Hild
ILIAS WG1, March 2008

10. Stefan Hild
ILIAS WG1, March 2008

11. Stefan Hild
ILIAS WG1, March 2008

12. Frequency noise projection: A smoking gun ?
Slide from October presentation
Frequency noise projection: A smoking gun ?
The change of the mystery noise from 550Hz to 1kHz tuning looks suspiciously similar to the change of the frequency noise transfer function.
Is there any correlation at SR-tuning of 350 Hz ???
Stefan Hild
ILIAS WG1, March 2008

13. Mystery noise vs frequency-noise-TF
550 Hz and 1kHz fit pretty well, but 350 Hz does not.
Could indicate that part of the noise is caused by frequency noise
Stefan Hild
ILIAS WG1, March 2008

14. Frequency noise
Part of the mystery noise was caused by frequency noise.
See Hartmut’s talk
Stefan Hild
ILIAS WG1, March 2008

15. Projections to uncalibrated errorpoints
In order to rule out any strange effects from calibration process we wanted to do noise projections to the uncalibrated errorpoints.
The gap turns to be of same size as for h(t) projections.
Stefan Hild
ILIAS WG1, March 2008

16. Time domain noise projections
Wanted to perform noise projections in time domain => taking phase correlations into account.
Frequency domain and time domain projections agree pretty well.
For more details, see Jerome‘s talk
Stefan Hild
ILIAS WG1, March 2008

17. New Projection: Beam jitter on main PD
Stefan Hild
ILIAS WG1, March 2008

18. Stefan Hild
ILIAS WG1, March 2008

19. Needs more attention and investigations ….
Holographic noise
Needs more attention and investigations ….
Stefan Hild
ILIAS WG1, March 2008

20. ... even more desperate ones ...
New Ideas are welcome . . .
... even more desperate ones ...
Stefan Hild
ILIAS WG1, March 2008