Evan, Matt, Lisa We took ~25 min of undisturbed data starting at Jul 31 2015 09:21:13 UTC , after the MICH FF improvement (and all the changes described earlier implemented), with the interferometer locked in low noise ~ 65 Mpc (according to SensMon). We saw a big glitch during this period (~9:28), a huge one right before (~9:18, right after the mich tuning was done), and another one at the end of the undisturbed period. We went back to commissioning mode as Evan is starting some noise injections for his noise budget.
I did injections into MICH (from 10:41:40 to 10:47:00) and SRCL (from 11:15:00 to 11:22:40) with all FF on.
About 30 s after turning off the SRCL injection, a number of photodiode signals associated with the AS port dropped suddenly by about 5% (in particular: AS DC, AS90, ASA sum, ASB sum, ASC sum, and AS45Q; notably, the OMC DCPDs, POP DC, MC2 sum, and IMC input power did not see this). After that, the interferometer glitched for about 30 minutes. This event happened at 11:23:31.05 and lasted for only a few milliseconds.
I did an injection into PRCL (from 12:21:50 to 12:29:00).
I did an injection into the ISS around 12:52:00. I think this measurement needs to be redone by injecting into the error point of the outer loop rather than the inner loop. With the outer loop closed it is now difficult to get good coherence between intensity and DARM below 300 Hz.
PSL Peri PZT servo ON/OFF test:
IFO was still locked when I came in in the morning, so I briefly switched the IMC WFSB YAW to PSL PZT feedback path at around 7:50 AM local time.
In the attached, references are with the servo on, current traces are without the servo.
Middle finger (300Hz bump) is greatly reduced in OMC DCPD, but the coherence for right and index finger slightly increased due to gain peaking (expected), and there is another gain peaking at 620Hz (again expected). The last one could be reduced further by adding a deeper notch but that might increase the 350Hz bump gain peaking a bit.
The servo was turned on again at about 8AM+-5min.