J. Kissel

Wrapping up the core optic suspensions standard rubbing check top-to-top transfer functions after pump down, I've measured the main (M0) and reaction (R0) chains of H1SUSITMX and H1SUSITMY. 
ITMX looks great and free of rubbing, no "ifs," "ands," or "buts".
ITMY shows poor response / low coherence in both main and reaction chain vertical.

Conclusion: (albiet a weak conclusion) I suspect something is awry with the ITMY M0 (LF RT) / R0 (LF RT) OSEM signal chain, with a slight preference toward it being a drive problem. I *hope* that it's an external-to-chamber problem.  More discussion below. 

Attached are the results.

Discussion of ITMY:
- Start with the comparison between previous measurements, allquads_2018-01-05_H1SUSITMY_All_Phase3b_ALL_ZOOMED_TFs.pdf, and flip to pages 3, 9, and  10 for the M0 V to V, R0 V to V, and R0 R to R. 
NOTES: 
    - These are particularly low coherence, and these are driven with the same excitation amplitude as ITMX. 
    - I tried to drive harder, in case the templates were tuned for some other configuration, and it saturates the DAC, so the templates *are* well tuned. 
    - As per normal, I was in the top coil driver state 1, i.e. that with the low-pass OFF, and therefore the most DAC range.
    - Also, there are features in the R0 R to R transfer function at 1.11 1.70 2.82 4.52 5.90 (+/- 0.01) Hz that don't correspond to any other DOF's resonances for either chain.

- Next look at the individual measurements detailed TF analysis, 2018-01-05_1944_H1SUSITMY_R0_ALL_TFs.pdf. Pg 3 and 4 are repeats of what you've seen, but 
NOTES: 
    - on pg 7 (L to V), pg 9 (R to V), pg 11 (P to V) which show the "expected" or "interesting" cross-coupling between the vertical DOF and others, one sees pretty good reciprocity. I.e. we see that what features and frequency response shape are seen in the V to ? TF are also seen in the reciprocal ? to V transfer function. This is evidence toward the sensors/electronics being a problem and not the suspension's dynamics. Admittedly, the P to V and V to P TFs look the least alike. These TFs *have* changed from the previous at-vacuum measurement of this suspension (see 2017-07-20_2358_H1SUSITMY_R0_ALL_TFs.pdf from LHO aLOG 37848), but it's unclear if one could claim that one was "better" or "more right" than the other.
    - on pg 15 (V to LF RT) and 16 (R to LF RT), one can see that both sensors are showing the same response to the drive (as was true in 2017-07-20 data set as well), but it just looks over all weaker. This implies that it's a *drive* electronics problem, not a *sensor* electronics problem.

A final note: other than
    - Aligning / Rebalancing the Reaction Chain,
    - Installing BRDs & NMBDs on the Main Chain, and
    - Resolving all in-vac cable grounding issues
we did comparatively little to this suspension.

Following all these clues, I was perusing aLOGs to see if I could find any hanging chads regarding the cable grounding issues, and found LHO aLOG 39675, but 
    (a) Those cables in question for ITMY were for R0's (F1 F2 F3 SD) and PUM (UL LL UR LR) signal chains, *not* for those involved with these transfer functions, namely the M0 (LF RT) / R0 (LF RT) signal chain, and
    (b) Richard assures me that *every* grounding issue in that aLOG was resolved (confirmed quickly by Besty in passing by LHO aLOG 39749)

As a final test, I ran the R0 V to V transfer function with all DOF's damping loops CLOSED -- see 2018-01-05_2214_H1SUSITMY_R0_V_Damped_WhiteNoise_0p01to50Hz.png for the results (BLACK is the 2017-12-20 data set, MAGENTA is the latest 2018-01-05 undamped data set shown the analysis .pdfs, and RED is the damped data set).
The only major difference (besides the -- surprisingly in-effective -- reduction of the primary vertical modes), is that the extra 1.11 1.70 2.82 4.52 5.90 (+/- 0.01) Hz features are reduced to the in-air 2017-12-20 level.

Measurement Templates:
/ligo/svncommon/SusSVN/sus/trunk/QUAD/H1/
ITMX/SAGM0/Data/2018-01-05_1828_H1SUSITMX_M0_WhiteNoise_L_0p01to50Hz.xml
ITMX/SAGM0/Data/2018-01-05_1828_H1SUSITMX_M0_WhiteNoise_P_0p01to50Hz.xml
ITMX/SAGM0/Data/2018-01-05_1828_H1SUSITMX_M0_WhiteNoise_R_0p01to50Hz.xml
ITMX/SAGM0/Data/2018-01-05_1828_H1SUSITMX_M0_WhiteNoise_T_0p01to50Hz.xml
ITMX/SAGM0/Data/2018-01-05_1828_H1SUSITMX_M0_WhiteNoise_V_0p01to50Hz.xml
ITMX/SAGM0/Data/2018-01-05_1828_H1SUSITMX_M0_WhiteNoise_Y_0p01to50Hz.xml

ITMX/SAGR0/Data/2018-01-05_1923_H1SUSITMX_R0_WhiteNoise_L_0p01to50Hz.xml
ITMX/SAGR0/Data/2018-01-05_1923_H1SUSITMX_R0_WhiteNoise_P_0p01to50Hz.xml
ITMX/SAGR0/Data/2018-01-05_1923_H1SUSITMX_R0_WhiteNoise_R_0p01to50Hz.xml
ITMX/SAGR0/Data/2018-01-05_1923_H1SUSITMX_R0_WhiteNoise_T_0p01to50Hz.xml
ITMX/SAGR0/Data/2018-01-05_1923_H1SUSITMX_R0_WhiteNoise_V_0p01to50Hz.xml
ITMX/SAGR0/Data/2018-01-05_1923_H1SUSITMX_R0_WhiteNoise_Y_0p01to50Hz.xml

ITMY/SAGM0/Data/2018-01-05_1828_H1SUSITMY_M0_Mono_WhiteNoise_L_0p01to50Hz.xml
ITMY/SAGM0/Data/2018-01-05_1828_H1SUSITMY_M0_Mono_WhiteNoise_P_0p01to50Hz.xml
ITMY/SAGM0/Data/2018-01-05_1828_H1SUSITMY_M0_Mono_WhiteNoise_R_0p01to50Hz.xml
ITMY/SAGM0/Data/2018-01-05_1828_H1SUSITMY_M0_Mono_WhiteNoise_T_0p01to50Hz.xml
ITMY/SAGM0/Data/2018-01-05_1828_H1SUSITMY_M0_Mono_WhiteNoise_V_0p01to50Hz.xml
ITMY/SAGM0/Data/2018-01-05_1828_H1SUSITMY_M0_Mono_WhiteNoise_Y_0p01to50Hz.xml

ITMY/SAGR0/Data/2018-01-05_1944_H1SUSITMY_R0_L_WhiteNoise_0p01to50Hz.xml
ITMY/SAGR0/Data/2018-01-05_1944_H1SUSITMY_R0_P_WhiteNoise_0p01to50Hz.xml
ITMY/SAGR0/Data/2018-01-05_1944_H1SUSITMY_R0_R_WhiteNoise_0p01to50Hz.xml
ITMY/SAGR0/Data/2018-01-05_1944_H1SUSITMY_R0_T_WhiteNoise_0p01to50Hz.xml
ITMY/SAGR0/Data/2018-01-05_1944_H1SUSITMY_R0_V_WhiteNoise_0p01to50Hz.xml
ITMY/SAGR0/Data/2018-01-05_1944_H1SUSITMY_R0_Y_WhiteNoise_0p01to50Hz.xml
ITMY/SAGR0/Data/2018-01-05_2214_H1SUSITMY_R0_V_Damped_WhiteNoise_0p01to50Hz.xml