A set of TFs were previously taken for the SR3 (HLTS) suspension (see LHO aLOG entries 12929 and 12945), to complete Phase 3a power spectra have been taken with damping loops both ON and OFF for all stages. These H1 SR3 power spectra have also been directly compared with equivalent H1 PR3 measurements (allhltss_2014-07-24_Phase3a_H1HLTSs_ALL_Spectra_D*.pdf). The plot key is as follows:-

Black Dashed Line = Expected Sensor Noise
Blue Solid Line = H1SUSPR3 2013−10−07_0800
Green Solid Line = H1SUSSR3 2014−07−24_1030

Summary:

Noise floors for SR3 are consistent with expectations. However, it should be noted that virtually all M1 stage OSEM channels exhibit narrow frequency comb features above ~20 Hz, which are only present in the damped power spectra and could therefore be be re-injected noise from the electronics chain and will need to be further investigated.

All data, scripts and plots have been committed to the sus svn as of this entry.