Sheila, Craig, Georgia

CHARD Y

We have increased the gain of CHARD yaw by 30dB.  At this point in O2 we were increasing the gain by 47dB, but that would be giving us too high a gain currently, so I reduced the filter gain.  Attached is a measurement taken with the CHARD Y gain at 10 (without the 30dB filter on), and no boost. From the measurement it seems as though we should be able to increase the gain of CHARD Y by about 20 dB, and engage the boost. This doesn't work. 

MICH Y

As Jenne's measurement from earlier today showed (43729) the MICH Y loop phase crosses instability at around 1.5 Hz.  When we tried to engage the boost for CHARD Y we lost lock due to a 1.5 Hz instability, which could have been from CHARD Y, but actually looking at the lockloss the instability shows up much more clearly in the MICH control signal.  We manually turned off the MICH Y low pass and things seemed a bit more forgiving (even though we still can't engage the CHARD boost and keep things nice and stable, we didn't loose lock by trying once the MICH low pass was off). 

CSOFT P

The stability of this loop around 0.5 Hz depends on both the optical lever damping and the HARD loop shapes.  Since we turned off the optical lever damping a few weeks ago it isn't surprising that this loop goes unstable and causes locklosses now.  The only need gain at around 0.5 Hz so that we can suppress the radiation pressure instability due to the suspension cross coupling, I cahnged the filters around and edited the guardian so that this loop should come on with a configuration more similar to DSOFTP, the only difference being 20dB lower gain.  We haven't tried this yet but in the morning in order to give this loop a gain equal to DSOFT pitch just increase the gain by a factor of 10 and use the filters that are in the guardian (They match DSFOT). 

Earlier today Gabriele looked at the TMS QPD combination that we are using, which for TMS Y is different for DSOFT and DSOFT.  We should fix this, but haven't been able to lock long enough to engage soft loops since then. 

POP_QPD before SRC ASC

We changed the order of these states since it seems to make the ASC engaging go more smoothly. 

CHARD P 

earlier today we were able to increase the CHARD P gain from 0.3 to 1, but not 1.5

Other locking things today

We have had a few intermittent problems with ALS today, with some glitches that have come and gone.  We have been seeing for a while that ALS DIFF noise is much higher when the COMM PLL is locked, so we edited the guardian to unlock the COMM PLL, lock DIFF, then lock the PLL before locking COMM.  We should probably try to fix the cross talk. We also had a time tonight and earlier today when the X arm PDH would not lock.  Craig and I went to EX to try to investigate, but the problem was gone by the time we got there, and there is no sign of the laser mode hopping. 

Earlier in the day we got rid of the CARM boost, after experiencing many  locklosses a minute or so after transitioning to ANALOG_CARM.  Without the boost things have improved.  It might be that with the extra acoustic noise around the input arm we can't use the boost. 

We've had many locklosses at the TR_CARM and RESONANCE states today.  

Started ring heater test for TCS

Ran the script that Georgia requested at 5:41:30 UTC. 

python /opt/rtcds/userapps/release/tcs/common/scripts/ring_heater_schedule.py ETMY -s now -d 3.0 -p 0.5