Evan, Sheila
The PSL has been working all night tonight. We got a chance to try SRCL feedforward. It works, but it doesn't improve the noise. We saw that we were able to reduce the noise coupling by 12 dB at first, but then later saw that the coupling was changing by about 6dB at most. The second time we tried it we did not get as good subtraction. Evan has new measurements of the SRCL coupling and frequency noise coupling to include in the noise budget over the weekend.
Other things:
We used the TMSY picomotors to center the beams on the QPDs, this didn't change the combination of QPDs we used for the ITM loops. We might want to check the normalization for the Y arm QPD next time we do inital alingment.
We can switch SRM coil drivers in full lock, PRM, PR2, SRM, SR2 are now in the guardian in the DRMI_ON_POP state.
We started to measure the ASC sensing matrix with all the loops closed including the ITM loops, we got a reasonable measurement for pitch, the data is all on disk although we had some trouble extracting it. We were in the middle of tuning the yaw excitations when we got another earthquake. We were moptivated to work on ASC because we have been aligning a little by hand before turning on the ASC all night, and we are hoping to find more diagonal signals so that we don't have to do this each lock.
Here are the new SRCL and frequency noise couplings projected onto DARM.
The good news is that we no longer seem to have a frequency noise coupling shelf around 100 Hz. It also seems that the SRCL feedforward pushes the SRCL noise down below 10−19 m/rtHz around 80 to 100 Hz. But somehow the noise in DARM in this region still seems to be nonstationary and (qualitatively) we haven't really seen any noticeable noise reduction here.
I repeated the SRCL injection measurement on Saturday, and got similar results as what is shown here.
The MICH and intensity noise traces are stale and need to be retaken. However, I did not see coherence between MICH control and DARM when looking at the control noises.