Thought I had posted this before, but couldn't find it, so here it is. Attached plots compare L2L measurements of the HAM1 GS13s on May 21 during corner pumpdown before adding the periscope viton and June 6 the afternoon after we added viton. The Q and frequency of the 71.8hz mode is somewhat reduced, but the neighboring 69.9hz mode is sharper now, so I'm not sure we gained much. The June 6 measurement was collected in air, so I would still like to collect a set of in-vac measurements. This could probably be done on a Tuesday if there isn't too much activity around HAM1.
I took 5-200hz matlab tfs this morning to compare to the 2 previous measurements above. It seems that the damping is quite effective now. I will try to look at the effect on the isolation filter design, maybe we can get some of the loop gain back. It would still be better to move these modes up above 100hz if possible.
