Sheila, Dan, Chris, Stefan Tonight we first spent time making the Guardian automation work all the way. After making sure our ASC loops work properly, we added the OMC_LOCK Guardian to ISC_LOCK Guardian control. We had several completely hands-off relocks, taking us all the way to DC readout. Since we often broke the lock trying new things, we got some relocking statistics: from lock-break back to DC-lock is about 15min. We notched violin modes (0th, 1st and 2nd harmonic) in DARM. This was required for driving ETMY L2, but can't hurt regular ESD operation either. Next we tries to hand off the ETMX ESD to ETMY L2 stage. For this we copied the LLO L2 suscomp filter to our ETMY. We balanced the gain by driving a line in both ETMX ESD and ETMY L2. We did quickly had off control, but we were battling instabilities at 0.4Hz and 1.8Hz (the suspension resonances), as well as ringing up violin modes. As a consequence we lost lock a few seconds later, before we could turn down the ESD bias. On the next lock, we again succeeded in the hand-off, and turned the ESD off. But there was still some saturation happening, just as we started seeing the noise floor fall. Finally, we found a gain configuration that kept the interferometer stable on ETMY (see below). However at the time the violin modes were so rung up that we had lots of extra noise due to saturation. We had one unexplained lock-loss at UTC 2015 3/14 10:11:08. PS: It is really nice the have 15min of thinking time between locks - without having to click any buttons... PPS: Happy birthday, Albert Einstein! =============================== For reference, below are the ETMY hand-off steps we used. In addition the filter FM6 (Q) in the L2 LOCK filter back of ETMY was on, as well as a gain of 20. ezcawrite H1:SUS-ETMY_L3_ISCINF_L_TRAMP 3 ezcawrite H1:SUS-ETMX_L3_DRIVEALIGN_L2L_TRAMP 3 ezcawrite H1:SUS-ETMX_L3_DRIVEALIGN_L2P_TRAMP 3 ezcawrite H1:SUS-ETMX_L3_DRIVEALIGN_L2Y_TRAMP 3 ezcawrite H1:SUS-ETMY_L3_ISCINF_L_GAIN 0 ezcaswitch H1:SUS-ETMY_L1_LOCK_L OUTPUT OFF ezcawrite H1:SUS-ETMY_L2_LOCK_L_GAIN 20 sleep 4 ezcawrite H1:LSC-ARM_OUTPUT_MTRX_2_1 -1 # all at once ezcastep H1:SUS-ETMY_L3_ISCINF_L_GAIN +1.2 H1:SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN +-1 H1:SUS-ETMX_L3_DRIVEALIGN_L2P_GAIN +-0.021 H1:SUS-ETMX_L3_DRIVEALIGN_L2Y_GAIN +-0.007
Some violin mode damping notes:
The modes associated with the ETMs are fairly well behaved, they all respond to the same sign and phase. The modes for ETMY are at 508Hz and above, they are damped using ETMY_L2_DAMP_MODE5, -60deg, gain=-50.
ETMX has modes between 505 and 508Hz, use ETMX_L2_DAMP_MODE5, zero phase, gain=50.
The 2nd ETMY harmonic at 1484.4Hz and others can be damped with ETMY_L2_DAMP_MODE6, phase=-60deg, gain can be as large as -10,000. (These gains will change when we switch the L2 stages to low noise? Haven't been keeping track of what state the coil drivers are in.)
The 1st ETMY harmonic at 1009.44Hz was rung up tonight, but I couldn't find a filter combination to damp it. (Pretty sure it's ETMY, since that's the mass we were actuating on.)
The ITMs are tricky. ITMY in particular has a few modes between 501 and 502Hz which require different phases. ITMX has modes at 501.25 and 503Hz which also may require different signs/phases. There is an ITMY mode at 504.87Hz which has filters prepared in ITMY_L2_DAMP_MODE3. A gain of -50, with zero phase works for this line.
The X-end tidal is railing during the search for ALS_COMM, possibly from the increasing microseism. I am leaving the Guardian set to DOWN. No unattended operations tonight...