Alexa, Evan, Peter, Lisa, Sheila

Today we increase the gain in the fast path off the common mode servo gain to 7dB rom 3dB.  This was needed to fix the problem in the ALS COMM loop shape (alog 17649. ) We originally tuned our TR CARM transition at an input power of 10.8 Watts, and we are now running at 2.8 Watts.  The IMC guardian is partially correciting the IMC servo gain for this change, but not compeletely, so the fast path gain was a bit different than what we had when we originally tuned the transition.  The new ALS COMM open loop gain is attached.  If we deicde to change the input power for the locking sequence we might need to revisit this, or do a better job compensating for optical gain changes in the IMC. 

With this gain adjusted, we were able to do the TR CARM transition without a problem, (at the original gain of -16dB in the common mode board input 1).  The new TR CARM open loop gain  (with improved phase as described in alog 16766)  is attached to alog 16766

We then moved on to redcing the CARM offset, and lost the lock severl times on the way (possibly due to bad alingment).  We have now moved the transition to RF DARM to a higher CARM offset (8 times the single arm power). We have attempted to turn on the DHARD WFS at the same CARM offset that we had been using (25 times the single arm power) but only PITCH was working. With just pitch running and manually alinging YAW, we have been able to go through the locking sequence but not transition CARM to REFL 9.

One thing we have noticed tonight is that the Y arm alingment that is good for green is verry different from the alingment that reduces AS DC.  This probably means that we could make the process easier by adjusting the camera position that the Y arm green WFS use durring intial alingment.