It seems that the range drop which happened on Friday is closely realted to the range drops we had been seeing before Daneil and Nutsinee lowered the CLF power (see comments on 52984)
We still see the distinctive low SNR lines of high frequency glitches in the control room glitch monitor, (although they seem less loud now), which previously were shown to go away when the squeezer was blocked (image) It seems that our glitch rate since friday has been just about 1/second of SNR 5 glitches, which is a bit lower than what we saw previously when the range dropped, but higher that the previously quiet state (compare today to Nov 8)
Since the CLF was lowered Nov 8th, we have continued to see a correlation of jumps in the now disconnected channel H1:ISC-RF_C_SQZAOM200M_OUTPUTMON and range jumps, although it isn't a consistent relationship (similar to what was seen in 53096) The attached screenshot shows that there was a change in the behavoir of this channel friday during the time when the range dropped and it has been more stable since then (but seemingly stable in the state that is correlated with worse shot noise in the IFO).
Some tests we could think of trying would be to lower the CLF power, adjust the waveplate to keep the CLF power the same while changing the AOM drive, or disabling the ISS on the CLF.
Any insights from hveto, lasso, or other detchar people and tools could be helpful.
After yesterday's maintence time the range has been back in the 117 MPc range (front end range which is a bit higher than GDS), and the behavoir of the monitor channel for the removed 200MHz driver is still related to the range. (Screenshot attached).
Comparig the glitch rate on the summary pages for today and yesterday shows that the glitch rate is again reduced when we are in the lower range state.
Yesterday durring the maintence window Richard and I went to the racks to attempt to understand better what this channel could be connected to. We didn't do anything that should have had an impact. We did find that there were BNC T's left in the drive input channels for both of the AOM drivers used for itensity stabilization. We removed these and replaced them with the right adapters, but this should not have any impact.
Mark also spent some time trying to understand where this channel is coming from, (H1:ISC-C_RF_SQZAOM200M_OUTPUTMON), no real clues came from that.
