J. Kissel, K. Izumi, D. Tuyenbayev As expected from preliminary analysis of the actuation strength change (see LHO aLOG 22558), DARM Open Loop Gain TFs and PCAL to CAL-CS transfer functions reveal minimal change in the calibration of the instrument. For these measurements, all we have changed in the CAL-CS model is switching the two signs in the ESD stage, which in turn cancel each other. As such, the only change should be the change in discrepancy between the canonical model and the actual current strength of the TS / L3 / ESD stage. Again, this change was small (sub ~10%, 5 [deg]), and has been well-tracked by calibration lines, so we will continue forward with focusing our efforts on determining how to apply the time-dependent corrections. Attached are screenshots of the raw results. Darkhan's working on the more formal results. Stay tuned! The after-bias-flip results live here: /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/DARMOLGTFs/ 2015-10-15_H1_DARM_OLGTF_7to1200Hz_AfterBiasFlip.xml /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O1/H1/Measurements/PCAL/ 2015-10-15_PCALY2DARMTF_7to1200Hz_AfterBiasFlip.xml
Jeffrey K, Kiwamu, Sudarshan, Darkhan
Some conclusions based on the analysis of the DARM OLG TF and the PCAL to DARM TF measurements taken after flipping the ESD bias sign:
- Together with the ESD bias sign flip we also inverted the sign of the ESD DriveAlign gain, this means that overall L3 stage actuation function sign was not affected by today's sign flip activites;
- Since L3 stage actuation function sign was not affected, CAL-CS front-end calibration and EPICS values for calculating kappas are still valid1;
- Actuation function analysis showed that flipping the ESD bias sign resulted in reduction of the ESD actuation stregth by 7-8% (LHO alog 22558);
- Change in ESD actuation strength was reflected in mean κtst calculated from calibration lines over 43 minutes of undisturbed data after the ESD bias sign flip; comparison of the most recent actuation and sensing function measurements vs. H1 DARM model corrected with kappas showed residuals at the same level as measurements vs. kappa corrected models before the sign flip (see attached plots).
1although the total L3 stage actuation function sign did not change, the ESD bias sign flip was reflected in two of the SUSETMY L3 stage model EPICS replicas in CAL-CS model: H1:CAL-CS_DARM_ANALOG_ETMY_L3_GAIN and H1:CAL-CS_DARM_FE_ETMY_L3_DRIVEALIGN_L2L_GAIN.
Below we list kappas used in the kappa corrected parameter file for the measurements taken after the ESD bias sign flip on Oct 15. We used 43 minute mean kappas calculated from 60sec FFTs starting at GPS 1128984060 (values prior bias sign flip are given in brackets, previously they were reported in LHO alog comment 22552):
κtst = 1.004472 (1.057984)
κpu = 1.028713 (1.021401)
κA = 1.003843 (1.038892)
κC = 0.985051 (0.989844)
fc = 334.512654 (335.073564) [Hz]
An updated comparison script and parameter files for the most recent measurements were committed to calibration SVN (r1685):
/trunk/Runs/O1/H1/Scripts/DARMOLGTFs/CompareDARMOLGTFs_O1.m
/trunk/Runs/O1/H1/Scripts/DARMOLGTFs/H1DARMparams_1128979968.m
/trunk/Runs/O1/H1/Scripts/DARMOLGTFs/H1DARMparams_1128979968_kappa_corr.m
Comparison plots were committed to CalSVN (r1684):
/trunk/Runs/O1/H1/Results/DARMOLGTFs/2015-10-15_H1DARM_O1_cmp_AfterSignFlip_*.pdf
As a double check we created Matlab file with EPICS values for kappas using H1DARMparams_1128979968.m parameter file and made sure that the values agree with the ones currently written in the EPICS. The logs from calculating these EPICS values was committed to CalSVN (r1682):
/trunk/Runs/O1/H1/Scripts/CAL_EPICS/D20151015_H1_CAL_EPICS_VALUES.m
/trunk/Runs/O1/H1/Scripts/CAL_EPICS/20151015_H1_CAL_EPICS_*
For the record, we changed the requested bias voltage from -9.5 [V_DAC] (negative) to +9.5 [V_DAC] (positive).