Sheila, Cheryl, Jenne
When Cheryl locked the interferometer after maintence day and calibration work was done this afternoon, the recycling gain was again low, (POP_A_LF around 15500 cnts), around the level we have started at in locks where the recycling gain degraded until loosing the lock over the last few days. (When the recyclcing gain is stable this is normally around 16500 cnts). Since LLO was not locked, we took some time to open the refl beam diverter and look at the camera for a msalignement.
We then opened the PRC1 ASC loops (POP A to PRM, slow loop) and moved PRM by hand, very slowly so that the CHARD and CSOFT loops had time to catch up. We moved PRMI pit alignment slider from -1419 to -1405 urad, and yaw from 518 to 537 urad. This increased POP A by about 400 counts. At the slightly better recycling gain the offsets on POP A were -0.35 for Yaw and -0.3 for pitch. As Cheryl mentioned in her alog, we lost the lock for reasons I don't really understand while adjusting pitch. There didn't seem to be any environmental problem, so it would seem likely that it was my PRM pitch adjustment that is to blame, but I was not doing anything different from what I had been doing for the previous half hour.
We may want to try these QPD offsets as a new set point for the PRC1 loop, depending on what the reccyling gain looks like when Jim finishes locking.
Cheryl and I also spent some time debugging the PRMI branch, which has had some bugs in it for a while that have probably been causing problems.
This lock also started with low recycling gain, and Jim and I decided to try changing the soft loop offsets instead of repeating the PRM expiriment. I added offsets to DSOFT P and CSOFT P (the normal offsets are still in the TMS QPDs, I have not touched those.)
The current offset in DSOFT P is 0.04, while CSOFT P has an offset of -0.02. It seems like we could probably keep moving CSOFT to more negative offsets and keep improving the recycling gain, but we decided just to go to observing and see what happens over the course of the lock. POP A LF is now at around 15600 counts.
If anyone wants to revert this in the morning, just set H1:ASC-DSOFT_PIT_OFFSET and H1:ASC-CSOFT_PIT_OFFSET to zero.