Marie, Sheila, Kiwamu, Lisa, Stefan
We tried a few things to improve the recycling gain tonight. We believe that the problem is with something in our PRC. We can see that the green power transmitted through the X arm stays stable as we power up, we think this means the optics are stable. When we move the soft offsets to improve the recycling gain we change the X arm alignment to follow something in the vertex.
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We started with dithering IM1+IM3. The IM1 dither was meant to test is we were clipping into the Faraday, we don't think that is happeneing because we could clearly see our dither in IM4 trans PIT and Yaw, but not in the sum.
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We tried moving IM3 and PR2 offsets. We saw taht IM4 trans pit moves as we power up, so we started by trying to correct this by moving IM3. We were repeatably able to improve the reycyling gain from 28 to 29 by moving IM3 by 3000 in pitch counts (we think this is calibrated in urad! Our inital starting point was 58495 on the IM3 pit slider, our best recycling gain was at 55515 urad). This seems like too big of a move to be the real drift that we are trying to correct, and is much larger than the move needed to correct the position on IM4 trans.
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We tried moving loop offsets in PRC2 (POPX-> PR3 loop) In pit we went +- 400 counts without seeing any real change, in yaw we saw a repeatable imprvement with a offset of +400 counts.
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We switched off the loop, moved optics, and broke the lock.
As TJ noted, since the computer problems earlier we are having trouble relocking the PSL after locklosses, with noise eater, PMC and FSS and ISS problems. It seems like trying to lock the FSS causes the noise eater to oscillate again after it has been reset.
Jeff K, Stefan, Peter, Kiwamu
We kept having the same issues with the PSL in this morning as reported by Sheila in the above entry. We now think that it is all fixed. Here are what we have done for fixing the issues.