I am summarizing here recent progress on SEI units, and providing guidelines regarding what needs to be done next week.
A lot of different configurations have been tried in the past 10 days.
Two main conclusions:
- We don't want to put low blends on Stage 2 to avoid low frequency noise reinjection ( see logs here and here)
- We have a lot of pick up between Z and RZ. Relaxing the Z actuation (higher blend) helps in Yaw (see logs here and here)
The best BSC-ISI configuration so far is:
Stage 1
- X, Y, RX, RY, RZ: TSheila blend
- Z: T750mHz blend
Stage 2
- T750mHz blends on all degrees of freedom
We've successfully implemented some sensor correction on HAM2-ISI in X (see log here).
It helps the absolute motion by a factor of ~4 in Yaw, but we have to check what the motion of the cavity looks like (see the to-do list below)
A bunch of improvements have been made on the commissioning scripts (see log here). Jim is finishing up the work started on Routine_6 and should commit that pretty soon.
We also created some simple scripts to make the commissioning/debugging process faster (see log here).
BSC-ISI Sensor Correction
By doing some comparison with the LLO configuration (see log here), it seems that the next big step would be to implement sensor correction on the BSC-ISIs. It would help us winning a factor of a few around 0.5Hz.
We already started to look into that and we should have some exciting results soon.
Cavity Motion Study/Common Control
Even if we had some promising results with sensor correction on HAM2, we need to check the motion in the cavity: reducing the optical lever motion (absolute motion) doesn't mean that the cavity is quieter.
One of the idea will be to implement sensor correction using the SAME ground instrument for HAM2 and HAM3. It will be interesting to see what the cavity is doing when both of the chambers are control by the same input signal.
We need to:
- Implement sensor correction on HAM3
- Compare PRCL when the sensor correction is on and off on both chambers
see above
DRMI locks have glitches, so best to use the long PRMI stretches. Typically, no one is touching it in PRMI mode. We are leaving it in PRMI_SB all night; you can use POPAIR 18 to find the on/off segments to check the ISI motion sensors versus the PRCL length control signals.
Additional Chores
TSheila Blends which are TBetter on all dof except Tcrappy on Rz, need to be added to ITMY & ETMY.
Unlock HAM6 HEPI and get it on position Isolation Loops--need to run HEPI TFs
HAM6 ISI TFs with HEPI Loops closed, develop/implement Isolationcontrollers.
HAMs 4 & 5 higher Level ISI controllers--on going.
Additional accomplishments with lots of help from Seb & JeffK:
Fixed HAM Isolation plot saving--many previous (HAMs 2 & 3) don't have plot s of the controllers.
Added Chamber/Date/ControlLevel info and Gain Peaking to controller plots.