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Reports until 08:25, Thursday 16 January 2014
H1 SEI
hugh.radkins@LIGO.ORG - posted 08:25, Thursday 16 January 2014 (9317)
HEPI Position loops installed on ETMX--T240 quieting revisited

Well I got fooled here and at the moment I don't have the data to say anything.  Referring to alog 2973, I said the loop closing on the HEPI position quieted the noise from the IPS that appeared to be getting to the T240s on the ISI stage1.  However, Friday night when Jim, Fabrice and I were closing these loops, Jim reduced the gain on the T240s; I failed to confirm they were put back to their nominal high position.  So the trend I posted indicating the great reduction in noise was only the reduction of the T240 gain.  Yesterday afternoon I put the gain back to where it should be.

The attached 10 day plot shows the new story.  The last part of the plot shows the period after the gain increase.  It is smaller than the noisy period before last Fridays position loop turn on; but, remember Keita reduced the pitch request of HEPI and just by the scaling it may be completely due to this.

All is not doom & gloom though.  All through the night, there were no T240 glitches and no watchdogs trips on either ISI or HEPI.  Of course this could be completely attributed to the reduced tilting.

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