Sheila, Dan, Evan

Yesterday and today we have tried to get the interferometer into a state where we can lock ALS with a CARM offset, lock DRMI on 3f, and then reduce the offset while staying locked. The lesson learned this weekend is that it is taking too long to get DRMI and ALS locked so that offset reduction can begin.

On the ALS side:

1. Yesterday the ALS DIFF guardian was a little too agressive in turning on the DARM loop, so Sheila and I have added some timers so that the full gain and the boots are engaged more softly.
2. We quickly remeasured the OLTF of ALS DIFF yesterday, and it looks almost identical to what was measured in LHO#15025 (i.e., a UGF of 8 Hz with 60° of phase).
3. Locking ALS seems to be straightforward, but a bit slow. The biggest time sinks here seem to be (1) initial alignment of the arms, and (2) finding the IR resonances. For (1), Alexa, Kiwamu, and I have been working on some modified LLO scripts that use baffle PDs to align the TMSs. We want to expand these so that the ITMs are also aligned using baffle PDs. For (2), we need a better strategy for finding the resonances. Although the ALS DIFF and ALS COMM guardians have "find IR" states, they weren't successful this weekend.

On the DRMI side:

1. Although DRMI was well-behaved yesterday, today we saw a reappearance of modehopping in the SRC. We tried realigning the corner optics several times (and the Y arm once), but this issue kept appearing and throwing DRMI out of lock. After unlocking and then relocking DRMI, it went away, for no reason apparent to us.
2. When DRMI was stable on 1f, we were able to transition to 3f with no issue. However, the mode-hopping issue continued to reappear intermittently.
3. We tried turning on the ASC with DRMI on 1f. It initially improved the POP18 buildup, but then overshot, so we had to turn it off.
4. The POP18 buildup in both PRMI and DRMI varies between 190 and 270 cts. This has been true for at least a week, despite multiple realignments. Previously, we've been getting buildups in excess of 300 cts.

ALS+DRMI, other:

1. Yesterday we were able to get ALS locked with a CARM offset. We tried getting DRMI to lock, but it refused. According to Sheila, this may mean we need to turn down the DRMI loop gains during locking to compensate for the increased optical gain from the arms.
2. Today (like Friday), work was completely stopped by a long earthquake. It started nearly 3 hours ago (ca. 2014-11-16 22:30:00) and continues to prevent us from locking.