Transcript University of Birmingham LISA Pathfinder Phasemeter PDR

Very brief update
on the GEO mystery noise investigations
Stefan Hild
for the GEO600 team
15th ILIAS WG1 meeting, March 2008, Cascina
Introduction
Photographs by A. Freise
Just a quick update: following up the mystery noise
session + brainstorming at last ILIAS meeting.
See: http://www.ego-gw.it/ILIAS-GW/WP1docs/hild_231007.ppt for further
detail…
Stefan Hild
ILIAS WG1, March 2008
Slide 2
How to tackle the mystery noise ?
Mystery
noise
Stefan Hild
ILIAS WG1, March 2008
Slide 3
How to tackle the mystery noise ?
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
Slide 4
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
Slide 5
How to tackle the mystery noise ?
Fundamental
noises
Upconversion
Scattered light
Mystery
noise
Projected
noises
Displacement noise
Yes / No ?
Exotic noises
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
Slide 6
Stefan Hild
ILIAS WG1, March 2008
Slide 7
Low vs high power
Nominal power
low power
The gap looks smaller at low power, but …
Stefan Hild
ILIAS WG1, March 2008
Slide 8
Low vs high power
… but the mystery stays roughly the same
Stefan Hild
ILIAS WG1, March 2008
Slide 9
Stefan Hild
ILIAS WG1, March 2008
Slide 10
Stefan Hild
ILIAS WG1, March 2008
Slide 11
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
Slide 12
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
Slide 13
Frequency noise
Part of the
mystery
noise was
caused by
frequency
noise.
See
Hartmut’s
talk
Stefan Hild
ILIAS WG1, March 2008
Slide 14
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
Slide 15
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.
Stefan Hild
ILIAS WG1, March 2008
Slide 16
New Projection: Beam jitter on main PD
Stefan Hild
ILIAS WG1, March 2008
Slide 17
Stefan Hild
ILIAS WG1, March 2008
Slide 18
Holographic noise
http://arxiv.org/abs/0709.0611
http://arxiv.org/abs/0706.1999
http://arxiv.org/abs/astro-ph/0703775
Stefan Hild
ILIAS WG1, March 2008
Slide 19
Stefan Hild
ILIAS WG1, March 2008
Slide 20