jeffrey.garcia@LIGO.ORG - posted 22:14, Tuesday 29 November 2011 - last comment - 10:05, Thursday 01 December 2011(1806)
H2 ITMY R0 Pitch Transfer Functions
Attached is a DTT whitenoise measurement of the ITMY R0 Pitch DoF with a reference from 11/23/2011. Today's measurement is in red and with a 0.01Hz resolution. Measurements were performed after today's mechanical adjustments.
Non-image files attached to this report
Comments related to this report
Note that this data was taken the in the interim because mechanical adjustments to the reaction chain. Newer over night data (full aLOG coming shortly) shows much less badness. However, the lessons learned from this transfer function: - Because only the higher resonant frequencies have changed, whatever mechanical problem that is causing the badness is likely *internal* to the suspended chain. - The most likely culprit: either cabling jumps between the stages are extra stiff for some reason (temporarily having it moved, cocked to one side, etc etc), or there was rubbing between chains of the the newly aligned lower stage flags. - It's not shown here, but the main chain was taken at the same time, and didn't show any particular badness, so all fingers point to the cabling. Moral of the story -- things (on the reaction chain) look better in future measurement, with very little mechanically changed.