= vertical TFs of PR2 (SF-GAS/BF-GAS-excited) for the health check =
1. SF-GAS / BF-GAS / BF-V actually oscillated :) this is not the designed one though.
-- 1st pdf shows the measured TF excited by BF-GAS. its time series during the measurement are in 1st png.
2. However, following strange stuffs were found:
-- one peak at 0.3 Hz (the lowest vertical mode) disappeared, 0.6 Hz peak shifter to 0.45, and 0.9 Hz peak appeared.
-- IM-V did not oscillate a lot.
-- the oscillation of SF-GAS-TF and BF-GAS-TF looked same except for the phase, it was was opposite in the time series.
-- when I used the BF-FR, the SF-keystone was moved as well to the oposite direction compared with BF-GAS.
= sanity check aroud IM =
3. Then, first I doubted that IM might be sitting on the EQ frame since I released BF-body / Recoil BF. I took a look around the IM from the side flanges, and I found some of the EQ stoppers were close to touching or might be touching. After I made larger gap between IM and EQ stoppers, the vertical positions shift of SF-GAS/BF-GAS/BF-LVDT was obseved: went to lower position (2nd png). (And thus some of them should have been touching to the IM.. also BF-keystone sat down on the EQ stopper again, i.e. K1:VIS-PR2_BF_DAMP_GAS_IN = -3420.)
4. I also confirmed that the IM, IR were free from the EQ frame.
5. Then I measured some spectra and found IM-OSEM including H1/H2/H3 did not oscillate properly. also I could not find the lowet vertical mode. Probably this implies that the IM is touching to IRM probably at OSEM flags (2nd pdf).
= Next =
-- 1. pull up BF-keystone/SF-keystone
-- 2. release IM from IRM. This should be done with 1. in principle.
I'm now thinking we will find the lowest mode when the IM is free from IRM.
-- After making larger gap between IM and vertical EQ stopper on its bottom and so on, some TFs were measured and the lowest vertical mode at 0.3 Hz was found. However, the peak at 0.6Hz did not show up again. Actually BF-GAS did not oscillate now, even though the DC position was changed by BF-FR. Also IM horizontal TF could not be measured. (maybe this has been happened before opening the top flange.)
I'm now thinking this might be caused by:
-- friction between IM and IR at horizontal OSEM-flags.
-- strong friction between BF-primary and its secondary coil holder.
We will do the sanity check about the above and then will start the OSEM adjustment.