nutsinee.kijbunchoo@LIGO.ORG - posted 01:21, Wednesday 15 June 2016 - last comment - 14:04, Wednesday 15 June 2016(27745)
Violin Mode damping work (cont.)
Stefan, Nutsinee
A very quick summary: ITMY modes rung up tonight. All the damp settings has been changed. I suspect ETMX damp phase might have been changed as well. ITMX didn't seen to have a problem. We suspect the ring heater changed the violin mode frequency.
Below I attached a screenshot of what works on ITMY modes tonight.
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We looked at the frequency of mode 8 last night, two nights before around GW151226 and after a O1 power ouitage (20151025 9UTC). (attached)
Two days ago the mode was heavily damped, so the frequency estimate might be a bit off. At any rate, all frequencies are within 3mHz (or 22deg of feed-back phase in the current band-pass filter). So we ough to be able to damp this mode consistently.
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