Evan, Alexa, Elli, Kiwamu, Rana, Keita, Sheila
We are getting closer.
Today it has been much more reliable and robust for us to get to the state where DARM is controlled on RF. Differences from yesterday that have probably helped with this:
The ISC_LOCK guardian takes us to an offset in TR CARM of 20. There we have been trying to transition to REFL9 I/TRY. We lowered the whitening gain of REFL9I which was saturating the ADC, we now have 0dB whitening gain and no whitening filters. The steps that we have been doing that are not yet in guardian are:
At this point, some kind of oscillation has been starting which eventually blows the lock. Some example times are 2:47:06 UTC and 3:13:01 UTC. The attached striptool shows both of these events. You can see the oscillation in POP18, AS 90, AS DC, and REFL DC. As I've been writing I've been letting the guardian try to lock on its own, it has lost the lock twice in the REDUCE_CARM_OFFSET_MORE state, I think this is because the DIFF offset wasn't adjusted well. I've extended the time that the servo runs before this step.
I've left DRMI locked, with the arms misaligned for seismic people.
This DRMI lock stretch Sheila's left us began undisturbed starting ~04:05 UTC. Here're some relevant conditions of the IFO. DRMI is Guardian is in requested state DRMI_1F_OFFLOADED. IM4, PR3, BS, and SR3 alignments must have been tweaked recently, as their alignments are not saved, according the Guardian. Corner station WFS are OFF ISS Second Loop is OFF Wind is low, <5 [mph] Seismic Env.: Band Limit [um/s] (12-hour trend) 0.03 - 0.1 = 4e-1 (steady) 0.1 - 0.3 = 2e-1 (on its way down) 0.3 - 1.0 = 3e-2 (steady) 1.0 - 3.0 = 1e-1 (Hanford is on shift and loud) 3.0 - 10 = 3e-1 (steady) Optical levers well centered (about ~5-7 [urad] off center in P&Y) for BS, ITMX, and PR3. ITMY and SR3 is a little further off centered (about 15-17 [urad] off center). BS Optical Lever Damping in P and Y is ON, no other Optical Lever Damping is ON. All corner station HEPIs are ON, position-sensor only, locked to the ground, ~4 [Hz] UGFs. ALL DOF isolation loops closed, including AC coupled HP and VP. BSC HEPIs have Z sensor correction ON. Corner Station HEPI Pump Servo is ON. All HAM-ISIs running ~30 [Hz] isolation loops, sensors blended with 01_28 filters (including HAM3!), sensor correction ON in X, Y, and Z. ALL DOF isolation loops closed. GS13s are in HIGH gain mode, with DeWhitening filters OFF. All BSC-ISIs running ~30 [Hz] isolation loops, sensors blended with ST1 X&Y 45mHz, Z 90mHz, RX&RY 250a*250b, RZ 750mHz ST2 X&Y 250mHz, Z, RX,RY,RZ T750mHz ITMs: ST1 RZ isolation loops are NOT closed, all other DOFs are closed ST2 only X&Y isolation loops are closed BS: ST1 RZ isolation loops are NOT closed, all other DOFs are closed All ST2 isolation loops are OFF ITM GS13s are in HIGH gain mode, with DeWhitening filters OFF. All relevant SUS happily damped.
Keita, Alexa, Sheila
The osciallation that was breaking the lock last night was at about 0.45 Hz, and shows up in all the quad oplev pitch signals. It looks like the soft mode in both arms, but the oscialltion in the two arms are not in phase with each other. There is some of this noise showing up in DARM, but not in the other LSC out channels, in the BS, PR3 or SR3 signals until after the lockloss
This shows up on the ITMs, and we are not actuating on the ITMs. This is strange, but one thing that we would like to try is using lower power.