Evan, Alexa, Lisa, Ryan, Sheila
Today we were able to lock about 7 more times todat, for at most a half hour.
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The gain needed for the transisition to RF CARM changed from an 8 in the input matrix to a 5. We checked several settings, but found no explanation for this change. The arm transmitted powers today have been 5-10% lower than on saturday morning.
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The guardian now takes us all the way to on resonance, in about 15 minutes most of the time. It fails often, maybe about half the time we drop the lock durring CARM offset reduction.
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We were able to measure the ratio of the in vac refl 9I signal to the normalized (digitized) signal, using a 785 with an exictation into the CM board and test points in the summing junction (plot attached). The gain on the in vac path was 31dB, while the normalized path had a gain of 0 dB (these gains are both before the measurement point). We made several attempts to transition to this signal, but haven't suceeded so far.
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DRMI lock acquisition has been much faster today than in the past, probably due to the BS limiter.
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We adjsuted the dark offsets in AS45Q
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ITMX oplev still seems to have significantly more drift than other optics, screen shot attached. If this is real motion it is too much for us to stay locked with, this is about a half a micron drift in less than 10 minutes.
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We haven't been using the WFS to servo the BS alingment, we stopped doing this because engaging the WFS would sometimes cause mode mopping and lock losses. Without the WFS we have slow drift tof the beamsplitter (as seen in AS 90) which might be causing some of our lock losses.
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We drove a line in DARM at 43.1 Hz and measured the response in ASAIR 45 and saw that the signal in Q is only 5 times larger than I. Evan tried to adjust the demod phase to improve this, but the situation didn't change.
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We added a boost to RF DARM, an integrator with a 2 Hz zero. The guardian turns this on before transitioning to CARM to REFL. We are also no longer using FM4 (which was a low pass with extra gain around the suspension resonances, which seemed unusable on friday night.) This needs further investigation.
We have many examples of locklosses from today. We have added lock loss states to the guardians, so we should be able to get a list of these off the Detchar summary pages or the command line utility.