J. Kissel

Betsy and Koji have left the chamber this evening with what they though should be a freely suspended collection of SUS in HAM6 (see more details of their work in LHO aLOG 28882), so I volunteered to run a health check, comparing transfer functions to the reference measurements I'd taken just before the vent. 

In short:
- the OMs all look identical to how they looked before the vent: free and with resonance frequencies and Qs where expected.  
- The OMC looks to have its top mass locked up in the Transverse / Roll direction (probably just a forgotten set of earthquake stops), but otherwise all modes look to have nicely high Qs. The resonant frequencies of all modes of the L, P, and V DOFs have all decreased slightly. It's as of yet unclear if this is because of the tiny addition of mass (6 [g] out of the old 7161 [g], or new 7167 [g]), or because of some other mechanism (like the top mass being locked in Transverse).

I've informed Koji of this assessment, but there's still plenty of in-chamber work to do, so we can continue to iterate to improve / restore the suspension dynamics.

I attach screenshots of the OMC transfer functions from DTT showing the locked M1 mass. BLACK is reference in-air measurements, and RED is the current state of the suspension. The PDF attachments are comparing the OMs with previous results; as mentioned above, nothing exciting in there.

Data templates:
/ligo/svncommon/SusSVN/sus/trunk/OMCS/H1/OMC/SAGM1/Data/
2016-08-05_0128_H1SUSOMC_WhiteNoise_L_0p2to50Hz.xml   ***
2016-08-05_0128_H1SUSOMC_WhiteNoise_P_0p2to50Hz.xml   ***
2016-08-05_0128_H1SUSOMC_WhiteNoise_R_0p2to50Hz.xml   ***
2016-08-05_0128_H1SUSOMC_WhiteNoise_T_0p2to50Hz.xml   ***
2016-08-05_0128_H1SUSOMC_WhiteNoise_V_0p2to50Hz.xml   ***
2016-08-05_0128_H1SUSOMC_WhiteNoise_Y_0p2to50Hz.xml   ***

OM1/SAGM1/Data/2016-08-05_0133_H1SUSOM1_M1_WhiteNoise_L_0p2to50Hz.xml
OM1/SAGM1/Data/2016-08-05_0133_H1SUSOM1_M1_WhiteNoise_P_0p2to50Hz.xml
OM1/SAGM1/Data/2016-08-05_0133_H1SUSOM1_M1_WhiteNoise_Y_0p2to50Hz.xml

OM2/SAGM1/Data/2016-08-05_0145_H1SUSOM2_M1_WhiteNoise_L_0p2to50Hz.xml
OM2/SAGM1/Data/2016-08-05_0145_H1SUSOM2_M1_WhiteNoise_P_0p2to50Hz.xml
OM2/SAGM1/Data/2016-08-05_0145_H1SUSOM2_M1_WhiteNoise_Y_0p2to50Hz.xml

OM3/SAGM1/Data/2016-08-05_0201_H1SUSOM3_M1_WhiteNoise_L_0p2to50Hz.xml
OM3/SAGM1/Data/2016-08-05_0201_H1SUSOM3_M1_WhiteNoise_P_0p2to50Hz.xml
OM3/SAGM1/Data/2016-08-05_0201_H1SUSOM3_M1_WhiteNoise_Y_0p2to50Hz.xml

All have been committed to the svn.

*** I don't recommend using the 2016-08-05_0128 templates for the OMC transfer function, because I paid no attention to drive strength or frequency resolution. They were older in-air templates, so I wanted to make sure I was comparing in-air references to the current in-air state. But unfortunately they have different requested frequency resolutions so matlab post-processing analysis is painful, and the drive has no low-frequency boost so coherence is less than it could be. In the future, I would use the templates that I tuned for in-vacuum from LHO aLOG 28736.