Vern asked for some of the pie charts I made for ER7 for the first weeks of ER8. Here they are, based on data from 15:00 UTC August 17th to 15:00 UTC on the 28th, with about 40 minutes of missing data.
A few notes:
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We are suceeding in the CARM offset reduction more often. Durring ER7 only 1 in 5 DRMI locks reached the nominal operating state. Now 1 in 3 DRMI locks reach the low noise state, and 75% of them make it through the CARM offset reduction.
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We have locklosses due to the beamsplitter coil driver switching (there is a transient due to analog switching), locking since this guardian state uses blocking calls these locklosses are listed in the pie chart as Low noise ESD ETMY, and probably account for most of the 11 locklosses from this state. This is a lockloss we did not have durring ER7 since we did not switch the BS coil drivers.
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We also had a series of locklosses from the state DRMI on POP. Durring this state we switch the state of the PRM coild driver. While this coil driver was causing huge glitches we took one coil out, in this condition the switching became unreliable and caused locklosses. This problem has been solved by replacing the chasis.
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In the first few days of the run we had difficulty with SRC ASC, which caused many locklosses from the states DC readout, Increase power, and other states neaar this part of the sequence. This is a problem that has been partially addressed, but will likely return. We hope to spend some commisioning time to better understand the phasing and sensing matrix for these AS WFS. It would be good to do this now, while the ASC is working.
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Although we have many locklosses from the earliest steps of the locking sequence, Locking arms green and Locking ALS, these locklosses are not much of a concern since they do not cost us much time.
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DRMI locking times are similar to ER7, the median time to lock is 4 and a half minutes (It was 5 minutes durring ER7). We still have some extremely long locking attempts (up to 2 hours!) I'm hoping most of these were commisioning.
Our duty cycle is a bit worse than it was durring ER7, although there are several reasons we would expect it to have improved. Some of the downtime can probably be explained by commsioning and calibration activities, althoug I haven't yet tried to take that into account. It will be easier to get a clear picture of things once we start running undisturbed more.