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Very brief update on the GEO mystery noise investigations
Stefan Hild for the GEO600 team 15th ILIAS WG1 meeting, March 2008, Cascina
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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
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How to tackle the mystery noise ?
Stefan Hild ILIAS WG1, March 2008
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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
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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
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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
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Stefan Hild ILIAS WG1, March 2008
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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
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… but the mystery stays roughly the same
Low vs high power … but the mystery stays roughly the same Stefan Hild ILIAS WG1, March 2008
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Stefan Hild ILIAS WG1, March 2008
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Stefan Hild ILIAS WG1, March 2008
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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
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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
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Frequency noise Part of the mystery noise was caused by frequency noise. See Hartmut’s talk Stefan Hild ILIAS WG1, March 2008
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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
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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
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New Projection: Beam jitter on main PD
Stefan Hild ILIAS WG1, March 2008
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Stefan Hild ILIAS WG1, March 2008
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Needs more attention and investigations ….
Holographic noise Needs more attention and investigations …. Stefan Hild ILIAS WG1, March 2008
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... even more desperate ones ...
New Ideas are welcome . . . ... even more desperate ones ... Stefan Hild ILIAS WG1, March 2008
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