[Varun, Jenne, Craig, Georgia, Elenna, Sheila, Camilla, Austin]
- Austin locked the IFO and brought us to PREP_DC_READOUT_TRANSITION
- ETMY MODE1 rung up the night before, and Jenne put the IFO in down. It is still high this morning, but not increasing. No settings are currently on to damp the mode
- Varun's comment on this alog says that the best settings to damp ETMY MODE1 are FM1, FM4 and FM6 with a gain of 0.01
- I turned on these setting st UTC 16:36
- This seemed to be increasing the ring up of the mode, so at 16:44 I changed the gain to -0.01
- increased to -0.03
- Some speculation: When locked at RF 2W, probably best to use negative gain to damp EMTY Mode1. Last night settings at DC readout 2W were BAD (see alog 62416), DC readout at 50W is a different story, perhaps there is a sign flip that needs to occur when we change states
- increased to -0.1 at 17:12
- Moved to DC readout at 17:25
- 17:43 moving to Engage DC violins
- engage dc violins changes EMTY mode 1 gain to 0.03 (not what we want). we changed it by hand to -0.1
- Moved to maximum power at 18:03
- Moved to NLN
- Craig turned off cal lines
- Varun starting OFI length injections, shaking at 0.65 Hz
- Driving at 50 microns saturated the OFI SUS, but Craig had not left the yaw slider at zero, moving slider to zero and retrying
- Varun was able to excite length at 50 microns, the attached plot shows his results
- Moving to yaw injections
- ampl: 3500 counts, gain of 1 > 10 microradians pp
- Varun unable to drive any higher than 10 microradians without saturating suspension
- *** redoing these measurements because the resonant freq is not 0.65 Hz for yaw (actually 1 Hz)
- Yaw injections redo at 1 Hz
- ampl: 1500 w/ gain of 1 = 10 microradians pp
- We cannot go more than 25 microradians without saturating the OFI SUS
- Yaw injections results
- Lockloss at 20:36 due to earthquake
- Relocking post earthquake
- needed to move PR3 again to raise COMM beatnote (was -17 dBm, increased to -12 dBm by moving PR3 .5 microradians)
- need to get out to ISCT1 soon and work on the beatnote!
- Lots of locking trouble due to ground motion
- Moving to full initial alignment after losing lock multiple times at DHARD_WFS
[Georgia, Craig, Varun]
We got back to NLN and turned off the calibration lines and turned up the ADS lines. Next, the scattering shelves as evident from the OFI L exc, we decided to drive the ZM6 suspension. The excitation parameters in awggui were 2000 counts of amplitude at 0.65 Hz, which corresponds to 5 micrometer of p2p.
We see scattering shelves when the ZM6 was driven, see plot attached. This suggests that we may be scattering of the HAM5 gate valve.
- While reqacuiring lock at SLOWNOISE_COIL_DRIVERS we saw a 0.37Hz ring up in CSOFT_P (see attached). It went down on it own, but it was kinda alarming. We may want to consider reduicing the CSFOT_P gain further.
- Related to Varun's comment above - we tried various offsets on ZM6, and did not manage to remove the noise in DARM. These tests were done in a rush and it might be worth revisiting them
- Misaligning it up in pitch causes a large scatter shelf, misaligning down in pitch does not remove the scatter shelf
- Taking the suspension to safe caused a bit scatter shelf
- Turning off the damping loops didn't seem to change things.
- Another thing we could try is pico'ing the OFI mirror.
- ITMY violin mode damping doesn't seem to be working. We need to find settings that work at 50W.
[Sheila, Varun]
We modeled the scatter from the longitudinal excitation of ZM6 in the measurement above. We estimate at 10 ppm (plot below) for future reference. The DCPD is calibrated to units of RIN and is closed-loop corrected using the calibration from May 2021. The code for the model and the template for measurement is at /ligo/home/varun.srivastava/LHO_work/O4_comm/2022_04_12_OMC_BS.
