mark.barton@LIGO.ORG - posted 12:02, Monday 04 March 2013 - last comment - 14:22, Monday 04 March 2013(5642)
MC1 and MC3 pitched
Cheryl reported that MC1 and MC3 were badly pitched relative to the last time she worked with them. Trending the M3 level signals shows that it went bad at about 20:30 UTC (12:30 PST) on Tue 2/19, possibly in connection with the removal of dummy masses in preparation for installation of PR3 and PRM (alog 5527). Travis looked and didn't find anything obviously touching, so Cheryl is going to check the table levelness. Then we'll do another round of TFs to confirm that it's fixed or provide further clues.
Images attached to this report
Comments related to this report
I looked into the HAM ISI sensors and found that they also show changes from before the temporary weights were removed to after both PR3 and PRM were installed, which does indicate that changes to MC1 and MC3 could be caused by ISI changes. The plot shows the March 18, 6AM to March 22, 6PM, so covers all the HAM2 weight changes during the week.
Images attached to this comment
Attached are HEPI trends showing maximum excusion during the unweighting/reweighting period. None exceed 200 counts (.0003"). After reloading the table with the suspensions, the largest change is ,0.0001"
Images attached to this comment
Just for future reference, the conversion for the HAM cps's is about 800cts/.001", according to the HAM Integration Testing Procedure. The biggest shift is ~1000cts, so about 1.25 milli-inches, which is basically the slop in the lockers.