[Washimi, Takahashi]
We installed the geophone pod into the OMC chamber. The in-vacuum cable and outside cable were connected. The signals were confirmed on the MEDM screen.
I just compared the geophone spectrum (red) to that before replacement of the OMC stack (blue) around April 2nd (klog:29043).
I cannot see a significant improvement at high frequencies, but this might be due to the in-air measurement.
An in-vacuum measurement is necessary.
unfortunately, there are no klog posts about the OMC vacuum opening, but in the schedule spreadsheet, it should be performed on April 8.
So the April 2 data was in the vacuum.
A comparison of the in-air ACC spectrum before/after the stack replacement was reported in https://klog.icrr.u-tokyo.ac.jp/osl/?r=30109.
