aLIGO LHO Logbook

H1 DetChar (DetChar, ISC)

jeffrey.kissel@LIGO.ORG - posted 09:17, Saturday 16 May 2015 - last comment - 11:10, Saturday 16 May 2015(18476)

Automated 1/2 hour locks for the past 8 hours!

IFO back up; bounce mode looks better (maybe a slightly different alignment?); 2.5 [kHz] violin harmonic is still quite rung up. 

Turns out our DMT session had just frozen on the wall -- the IFO has been locking itself for the past 8 hours!! The lock stretches have only been ~1/2 hours long though, I'll see if its these poorly damped modes.

Robert has joined the party, and he plans to do injections later in the morning, but for now I've checked the undisturbed bit at 2015 May 16 16:10:00 UTC.

Comments related to this report

jameson.rollins@LIGO.ORG - 09:43, Saturday 16 May 2015 (18479)

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Wow, that is awesome. Re-locked itself all the way from DOWN to LSC_FF 8 times overnight. Very very cool.

jeffrey.kissel@LIGO.ORG - 09:32, Saturday 16 May 2015 (18478)

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Lost lock at 16:23 UTC.

Looking at some lock loss plots and ASAIR 90, the symptom seems to be a slow, 0.3-0.4 [Hz] oscillation in MICH that slowly builds up over time. Maybe this the is 0.4 [Hz], first longitudinal mode of the ITMs getting slowly rung up from radiation pressure? #wildspeculation

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jeffrey.kissel@LIGO.ORG - 11:10, Saturday 16 May 2015 (18481)ISC, SUS

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Stable lock attempts continue, I've been able to measure a high-resolution ASD, and identify that it's a competition between the ETMX and ITMX's bounce mode at 9.77 and 9.84 [Hz] being rung up the most. I'm trying to hold the ISC_LOCK guardian in DC readout (before the coil drivers get switched to low range) and noodle the with top mass bounce mode damping settings on these SUS to see if I can get better action. But it's not working out well at all. I'll keep exploring the parameter space...

The remarkable thing is how consistent the lock-acquisition sequence is -- nice work commissioning vanguard!