jeffrey.kissel@LIGO.ORG - posted 20:08, Tuesday 11 October 2016 - last comment - 19:10, Wednesday 12 October 2016(30431)
Another DARM OLGTFs and PCAL2DARM TFs; Confirms CAL-DELTAL Inaccuracy is not Lock-Stretch/Alignment Dependent
J. Kissel, D. Tuyenbayev We've grabbed another set of calibration measurements of the IFO's sensing function in order to build confidence in our newly commissioned front-end tracking of time dependent model parameters, and to confirm the discrepancy seen yesterday (LHO aLOG 30391) was not something funny about that lock stretch. Indeed the discrepancy remains. We've found bugs in our code that compares our DARM model against these measurements, so we can't yet confirm exact numbers like optical gain, DARM coupled cavity pole frequency, or SRC detuning spring frequency to offer a proposed change to the CAL-CS front-end parameters to fix it. We'll hopefully have something by tomorrow. Attached are screenshots of the measurements and the DARM loop parameters during the measurement. Timeline: (in UTC) 2016-10-12 01:30:00 -- IFO in stable Nominal Low Noise (PCALY calibration lines are ON); IFO undisturbed 01:46:00 -- IFO sufficiently thermalized to start measurements; PCALY lines turned OFF 01:47:48 -- PCAL2DARM measurement begins 02:05:48 -- DARM OLGTF measurement begins 02:24:00 -- measurements done; PCALY lines turned back ON; IFO undisturbed 02:40:00 -- Official Undisturbed period ends (but no one has done anything with the IFO since, up to 03:06 UTC) Data files (which are exported and committed to the SVN): /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER10/H1/Measurements/ DARMOLGTFs/2016-10-12_H1_DARM_OLGTF_4to1200Hz.xml PCAL/2016-10-12_H1_PCAL2DARMTF_4to1200Hz.xml
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J. Kissel, D. Tuyenbayev,
These are kappas calculated in the front-end after the TF measurements have been completed.
The optical gain is still ~15% lower w.r.t. the value in the DARM model parameters and the coupled-cavity pole frequency is ~ 340-350 Hz, which is higher compared to the yesterday's value (LHO alog 30391).
There's still more noise in the calculated values of fC. The SNR of the 331.9 Hz line is affected by a slightly increased noise in the [0.2, 1.0] kHz band.
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Doing the same thing as was done in LHO aLOG 30475, I've grabbed similar undisturbed data from the times quoted in the original entry, and replotted them in matlab after doing some rudimentary math. The 15 minute (900 sec) average value (starting at Oct 12 2016 02:39:00 UTC) for all of the time dependent parameters just after the sweeps are: Param Units Mean Std kappa_{C} [ ] 0.868 pm 0.01 f_{cc} [Hz] 325 pm 5.5 Re: kappa_{PU} [ ] 1.01 pm 0.0089 Im: kappa_{PU} [ ] 0.0007 pm 0.015 Re: kappa_{TST} [ ] 0.998 pm 0.011 Im: kappa_{TST} [ ] -0.010 pm 0.0091 Input Power [W] 51.8 pm 0.029 The script to generate these values lives in /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/PreER10/H1/Scripts/CAL_EPICS/get_fe_tdep_params.m
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