J. Kissel

I've taken new DARM open loop gain and PCALY to DARM transfer functions to validate the current calibration. During the PCALY to DARM transfer function, I take the transfer function from PCALY's RX PD (calibrated into [m] of ETMY motion) and the CAL-CS front-end's DELTAL_EXTERNAL (calibrated into DARM [m], which -- since we're driving ETMY -- is identical to [m] of ETMY motion). These two different methods agree to within 4% and 3 [deg] over the 15 [Hz] to 1.2 [kHz] band. The calibration discrepancy expands to a whopping 9% and 4 [deg] if we look a frequencies between 5 and 15 [Hz] ;-).

I think we're in great shape, boys and girls.

Details
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- CAL-CS does not correct for any slow time depedence (optical gain, test mass actuation strength, etc), so any agreement you see with the current interferometer is agreement with the reference model taken on Sep 10th 2015 (LHO aLOG 21385).

- In the previous measurement, Kiwamu had to fudge the phase by ~90 [us] to get the phase to agree. Now that we've updated the cycle delay between sensing and actuation to 7 [16 kHz clock cycles] to better approximate the high-frequency frequency response of AA, AI, and the OMC DCPD signal chain, we no longer have to fudge the phase -- AND the phase between the two metrics agree. NICE.

- I've made sure to turn OFF calibration lines *during both of these measurements, but there should be ample data just before and just after with calibration lines ON, such that we can compare our results against theirs to help refine our estimates of systematic error.

- The measurements live in
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/DARMOLGTFs/2015-09-23_H1_DARM_OLGTF_7to1200Hz.xml
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/PCAL$/2015-09-23_PCALY2DARMTF_7to1200Hz.xml
and have been committed to the CalSVN. We'll process these results shortly, and perform a similar analysis as Darkhan has done in yesterday's aLOG 21827.