keita.kawabe@LIGO.ORG - posted 10:43, Tuesday 19 April 2016 - last comment - 13:43, Tuesday 19 April 2016(26650)
ITM OPLEVs are totally off
In the week of LVC there was a beam manifold vent (alog 26065). After the volume was pumped down, ITM oplevs were totally off and never came back (attached). (It should be grouting during that week, not the vent itself.)
Basically the beam is in a single quadrant, both for ITMX and ITMY.
It's the oplevs, not the mirrors themselves, as we went to a full power lock while the oplevs are off.
Don't enable oplev damping or do oplev-related measurements until they are centered again.
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FYI, ITM OL damping has been on all the time. Even in the best case it shouldn't have helped anything, but it might have made things worse.
Suppression spectrum for the ITMX_L2_OLDAMP_P loop. No effect at nominal gain.
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