jeffrey.kissel@LIGO.ORG - posted 13:52, Tuesday 15 November 2016 - last comment - 15:11, Tuesday 15 November 2016(31504)
New Sensing Funciton Data Set; Calibration Lines turned Back ON
J. Kissel Travis was able to grab a PCAL2DARM/DARMOLGTF sensing function transfer function set last night (see LHO aLOG 31485) -- for convenience I reiterate the location here: /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER10/H1/Measurements/ PCAL/2016-11-15_H1_PCAL2DARMTF_4to1200Hz_fasttemplate.xml DARMOLGTFs/2016-11-15_H1_DARM_OLGTF_4to1200Hz_fasttemplate.xml and attach a screen shot. The data has been committed to the CalSVN. It looks like the DARM cavity pole was low during this lock stretch, but otherwise the optical gain is ~5% low as we've seen in the last of measurement at 30 [W]. We'll get one more of these at 30 [w] for processing and get on with the analysis. Apologies for the delay in analyzing this data -- I'm really struggling for person power beyond me, given the current poor duty cycle and my needs to be the recovery team as well (Kiwamu's in Canada, Evan's helping out LLO).
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I've re-read Travis's entry (LHO aLOG 31485) and found were not running SRC1 loops during the lock stretch in which this measurement was taken. The suspicion is that SRC1 alignment loops are going unstable, so turning them off would improve the duty cycle. That investigation is on-going. However, with the SRC1 degree of freedom uncontrolled, as we have found from 50 [W] experience, the DARM coupled cavity pole frequency drops and moves around much more, among other things. That's why we see the increased frequency-dependent discrepancy in the PCAL 2 DELTAL_EXTERNAL transfer function. Unfortunately -- assuming we can figure out what's wrong with the SRC loops and fix it -- this means measurement won't be representative of the O2 configuration. We'll do what we can to salvage it, but ideally, we'd like to take it again. In Summary: SRC1 P&Y Loops OFF Input Power Mean: 30.7 [W]
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