Motivated by our locking difficulties at the end of last week, I downloaded guardian state data for the last two weeks to look into our locklosses durring the CARM offset reduction.

To start with the good news, the script that I use to do this automatically makes a few figures that tell us about our duty cycle, and we are doing well overall. As usual, I am only looking at the guardian state, and not considering any intent bits.  My reaasoning is that the hardest part is getting and keeping the IFO locked, and that is currently the important limit to our duty cycle. 

• We have been locked in the nominal low noise state for 83% of the time (compared to 68% for the last week of ER8).  A good part of the improvement is probabably because the ground has been quieter in the last 2 weeks, although I didn't try to quantify that. (guardian state pie chart is the first attachment).
• About half of our DRMI locks result in nominal low noise locks (33/64).  A lockloss pie chart is in the second attachment. We have fewer locklosses in the late stages of the guardian, which could be because we are waiting for the first sets of ASC loops to engage before we engage the soft loops (alogs 21583 21587)
• The median low noise lock stretch was 5.5 hours long, while the longest was 59.7 hrs long.  A histogram of the length of low noise locks is in the third attachment.

The main weakness in our lock acquistion sequence now seems to be the early steps of CARM offset reduction, as we saw yesterday. 

•  We certaintly have a harder time with these early steps of CARM offset reduction when the ground motion is high, which explains most of our down time from the 2nd to the 3rd.
  • The 4th attachement show a histogram of locking attempts bined by ground motion, which is the maximum of the sum of the Y direction blrms for 30mHz-100mHz and 100-300mHz bands durring the locking attempt. I chose the Y direction at Y end because that tends to have more wind induced tilt, so this should include the impact of wind, earthquakes and useism.  You can see that we struggle to lock when the ground motion in these bands is above 250nm/sec, although occasionally we do suceed.  In the version of the plot attached here, I called a locking attempt sucsesfull if it reached the low noise state, but the plot doesn't change much if you instead make it for locks which make it past the stage where the DHARD ASC loops come on. 
  • The 5th attachment shows the ground motion over the last week, with a plot of the range to illustrate where the long stretch of downtime was.  Clearly, this was mostly time when the ground motion was high enough to cause us locking difficulties.
• One thing that might be hurting us in these early stages of CARM offset reduction is OMC flashing, see alog 22237. We will pull this off resonance using the guardian soon.  These OMC flashes are mostly not bright enough for us to see them on the AS camera, and it may just be that we see more OMC flashes when there is more light at the AS port because of bad alignment or high ground motion.