Craig, Sheila, Jenne, Gabriele

We made enough progress tonight that we should be ready for calibration sweeps tomorrow.  The guardian as the graph is now should be able to take you to LOWNOISE_ESD_ETMX.  

• Violin modes
  • During the maintence period today the violin modes were rung up.  I edited the guardian to slowly increase their gains as they damp if the gain setting is lower than the max_gain listed in LSC params.  
  • ETMY mode 6 had the gain set to 0 in the guardian, but it was rung up tonight and a gain of -6 was fine, so I've put this in the guardian. 
• The first time we transitioned to the ITMX ESD, a mode at 6049.73Hz rang up and broke the lock.  We modified the notch in DARM for the 4.7kHz violins to also include a notch around 6050Hz.  Craig made a monitor for this mode in ITMX_L2_DAMP_MODE10, it rang down very quickly on it's own so it's not a violin mode (spectrum of 64kHz DCPD channel is attached).
• The 45 MHz reduction that Jenne worked on yesterday is in the guardian path now, before we increase the power. 
• We had several locklosses in a row caused by rough engagement of SRC2.  Craig reordered the SRC_ASC state so that the gain is ramped on. 
• We attempted once to go to 25W of input power, we still had a large drop in POP18 power, and after a few minutes at 25W we lost lock (You can find this in the new lockloss tool which is still being developed here: lockloss).  Yesterday we reduced the POP45 whitening gain by 12dB, I reduced it further after that lockloss, but that may be unnecessary.  
• We switched back to the ETMX ESD in low voltage mode.  We used a gain of -40 in the drivealign filter bank to roughly match the gain of the ITM ESD.  The second attached plot shows a comparison of the response of DARM to excitation at drivealign for both ITMX and ETMX after switching to the low noise driver.  The third attachment shows a quick DARM OLG measurement. 
• We edited the guardian state ESD_ITMX (renamed LOWNOISE_ESD_ETMX) so that it transitions DARM control to ITMX, switches the EX ESD to low voltage mode, and transitions DARM back to ETMX ESD, leaving L1+L2 on ETMY. There were several edits to PREP_FOR_LOCKING and ALS_DIFF needed to be able to relock after this. 
• I unlocked the interferometer using the MICH_OLG_NOISE_FULL_LOCK template at 2018-10-10 07:23:45 UTC