Evan, Gabriele, Sheila

Today we learned how to lock the IFO with a higher recycling gain.  First we locked the IFO and adjusted the alingment again to get a recycling gain of ~40 similar to what was done yesterday, realinged green down the arms by moving TMS and the QPD offsets (QPDs were only necessary for the X arm) and updated the camera positions. With the improved recycling gain we had to make some changes to both the CARM offset reduction sequence and the ASC.

CARM offset reduction 

All the changes we made to the CARM offset reduction were consistent with having higher arm build ups because of the better recycling gain.

• We reduced the TR CARM offset at which the transition to RF DARM happens, to keep in similar in physical CARM offset  to what we had before.  
• We also moved the transition to normalized REFL AIR 9I to a higher TR CARM offset, we saw that the refl signal was not a good error signal at the lower arm power we had used previously.
• We had to readjust the transition to analog CARM as well, we are now ramping the gain up to the old settings to get a ugf of 15kHz, we aren't sure why we had to change the transition process although we are usign the same gain. 

ASC

We found the same situation as what Evan and Gabriele noted yesterday, that the sign on the PRC2 loops has flipped.  We have also turned off some roll offs and increased some gains to make it easier for us to find the good recycling gain.  (These may introduce noise in to DARM so we may need to add them back latter.) Specifically,

• We have taken the two roll offs in FM9+10 out of DHARD, the DHARD gain is increased from 10 (PIT) and 5 (YAW) to 14 and 14.  
• For CHARD, the roll offs in FM10 are also off, the gains both changed from -1 to -6.  
• For PRC2 the sign has flipped, the gains went from +2 to -2
• SRC2 has gains of 2, rather than 1.  This loop is closed without any offset in DRMI, opened, and now when we close it again in full lock we engage it with an offset that is adjusted each time so that the loop engages with an error signal of zero the second time. ( We will see if this works).
• PRC1, SRC1, MICH and INP1 are the same.

These changes are all in the guardians now,we have not compeltely tested the ASC.  We also can turn the ASC gains back down to what they used to be.  We were able to turn all the ASC on with a recycling gain of 39.6, however in the bounce, violin and roll mode damping broke the lock.  We think this is most likely to be the roll mode damping that is a problem. 

SUS chassis needing to be power cycled

Also, the ETMX PUM watchdog is tripped, it seems like each time the watchdog trips on only one of the coils we have to drive to the end station to power cycle the chasis.  We also had to drive down there earlier in the evening to power cycle the UIM coil driver chassis.