jim.warner@LIGO.ORG - posted 16:18, Sunday 13 September 2015 - last comment - 00:31, Monday 14 September 2015(21473)
End of shift summary
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Title: 9/13 Day Shift: 17:00-23:00UTC
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State of H1: Trying to lock
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Support: Jenne came in early, Sheila later
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Shift Summary: Bad shift. Spent most of it changing alignments, resetting alignments, watching futile atttempts to catch DRMI.
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Activity Log:
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I came in and helped Cheryl reset HAM5 ISI, which is difficult, you have to reset the watchdog and the rogue excitation watchdog. Reisolating will probably require putting GS13s in low gain as well.
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Otherwise I spent it redoing alignments, and didn't get around to keeping a log, but Jenne and I were the only ones doing anything on the IFO, mostly.
While looking into some of the problems Jim was having today, I found an error in the ISC_DRMI guardian. The clearing of history was reworked a few weeks ago to use fast ezcas, but the order of things became incorrect, (gains were zeroed, histories reset, then inputs turned off. This means that the integrators in the top stage were cleared and then reaquired some history before the input was turned off.)
Now this is fixed, so inputs are turned off, gains are zeroed, then history is cleared.
This was causing DRMI to sometimes be misaligned if PRMI was locked first, the lock was dropped, and we attempted to relock DRMI.