The BS suspension seems to be healthy. The recovery work today comprised the following tasks:
- Using the fishing rods (FR) setting the GAS filter keystones to zero per the LVDTs
- Set the oplev signal to zero using the IM pico-motors (F0 yaw adjutment mechanism is not operational in the BS suspension).
- Measurement of transfer functions to assess the health of the suspension.
Conditions
In vacuum and at 25 ºC
The original positions of the GAF fishng rods stepper motors were
- Motor #0 BF: 195,000 steps.
- Motor #1 F1 : 1,800,000
- Motor #2: Channel not working.
- Motor #3 F0: -925,000 steps.
Botom filter
The keystone was at -273 µm. It was brought to zero with the FR stepper motor at the position of 50,000 steps.
Standard filter F1
It was not possible to bring the keystone to zero. The lowest possible was 1,148 µm. I left it at 1,190 µm with a stepper motor position of 1,910,000 steps.
Top filter F0
The keystone original position was -2,240 µm. I set it to zero by putting the motor at 96,340 steps (see entries 7694 and 7675).
Transfer functions
Directory: /users/enzo/BS_vacuum2/
I compared the measured TFs with the ones taken on 2019-01-21 at /users/enzo/BS-phase2/
Currently I post the ones for the IM, but the rest will follow. The comments are:
- In some cases the phase was slightly different from the reference likely because a small drift in the very last stages of to the pumping.
- In the case of IM roll a small peak appeared just below 400 mHz.
