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

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

GEO‘s sensitivity for last 20 days of S4

Peak sensitivity ‚drifted‘ during S4(much more than at other frequencies)

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

BLRMS of H(t) vs glitch rateH

(t)

BL

RM

S 9

90-1

000

Hz

Gli

tch

rate

700

-200

0

Hz

Found relation between glitchrate and peak sensitivity.

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

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Spectrograms of differential EP-PH

igh

gli

tch

rate

L

ow

gli

tch

rate

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Gliches vs BLRMS @ 1 kHz

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Timedomain distribution

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Noise projections

1 kHz glitches can‘t be explained by our current set of noiseprojections

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

lk

kik tm

hk

kik tm

Triggers

km

k

ht

lt

= mean

= standard deviation

= high threshold = 25

= low threshold = 5

Index i = subsegmentIndex k = frequency bin

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

SNR distribution

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Number of pixels

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Duration of bursts

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)

Stefan Hild Ilias WG1 meeting, Hannover, April 2005

Time-delay between glitches

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

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 ?