Scraps of text for incorporation in the VIS Meeting Minutes
Type B (Mark)
Report for week of 12/17
- Miyakawa-san worked on the BS real-time model and the gain/offset settings for the F0 LVDTINF block were lost, so we reentered them and did a new safe.snap file.
- We unlocked the IP adjusted the level with the jacks to center it. As hoped, this also improved the alignment of the chain insecurity structure and fixed a touching issue.
Hirata-san installed and cabled the new F0 yaw stepper. We had allowed plenty of reserve mass, so there was no problem getting back to nominal height of the keystone. [As of Thursday afternoon, it had not yet been tested - UPDATE?]
- We found that the Nikhef method Fabian had used to tune the F0 LVDT driver gave an artificially narrow working range, so he retuned it with Enzo's method and recalibrated the LVDT.
- Fabian did a vertical position survey with all the GAS filters at nominal and found the height of the RM above the SS bottom plate was about 2.5 mm lower than in the CAD. This is about what we expected from a chain 7 mm longer than CAD and and F0 keystone set to 5 mm higher than CAD. In future we can survey to either the optic or the security structure as convenient, and we are in the range where we should easily be able to match the correct beam height with the jacks under the PI.
- We got two OL viewports for SRM from Akutsu-san, and will install them sometime in January, whenever we have a free moment. Akutsu-san pre-torqued the inner ring of screws around the glass, so we only need to torque the outer bolts.
- We took transfer functions for the IM. All of them look good except IM-T. We will inspect the payload next week in case anything is touching or rubbing.
- Hirata-san opened the +X door of the vacuum chamber so we could inspect the payload, especially the OSEMs. We closed it back and covered with tape a small gap at the door.
- We also got a camera viewport for SR3 from Akutsu-san and will install it sometime in January.
- Hirata-san installed and cabled the new F0 yaw stepper.
- Enzo calibrated the SR2 OL. He noted that with the standard f=2500 mm collimator, the angular range was only about 100 µrad in pitch and 150 µrad in yaw, which is rather less than Enomoto-kun's preferred range of more like 400 µrad, so we borrowed f=1100 mm and f=3500 mm collimators to characterize. Enzo did f=1100 mm and will do f=3500 mm soon.
- Hirata-san installed and cabled the new F0 yaw stepper. We did not have enough reserve mass for SR2, so to save 300 g we had Mesco make a new, lighter top plate, and Hirata-san ultrasonically cleaned it. We were then able to get the desired F0 keystone height with about 200 g to spare.
- The day after installing the yaw stepper, we noticed the RM was touching the security structure but we were able to move it free by adjusting the cylinder with the spring and leaving the stepper motor in its nominal position. After this, for the other suspensions, we always checked the yaw of the payload immediately after installing the stepper.)
- Enzo did a historical survey of the temperature as the various suspensions were being built and concluded that ideal operating temperature would be 25°C in the BS/SR2 area and 24°C for SR3/SRM.
- Mark wrote a bash script to log all the GAS filter heights and LVDT actuation offsets, and an Excel spreadsheet to analyze the data to get an overview of the heights of the suspensions and the amount of height adjustment being used. He also reviewed old TF data to get near-DC values for the effect of GAS actuation on GAS height. This uncovered a few issues with calibration settings (such as for BS F0) having been lost because they hadn't been recorded in a safe.snap file, which we fixed.
To-Do Lists, Schedule
Plan for week of 12/17
- Final alignment of SRM payload, plus BF and SF GAS.
- (Time permitting) unlocking/centering/tuning of IP.
- Installation of Enomoto-kun's beam target on SRM (if available).
- Installation/testing of F0 steppers on SR2, SR3, SRM, and (hopefully) final vertical height adjustment.
- Installation of viewports on SRM.
Plan for week of 12/24
- Mark and Hirata-san on holidays, Enzo at Mitaka, Fabian.
Plan for week of 1/7
- Make sure BS is floating, recenter OL to capture current yaw position.
- Vent BS.
- Inspect BS F0 blades for cracks.
Install new BS F0 FR, and (if necessary) auxiliary CuBe spring.
- Confirm geometry of LVDTs, geophones, FRs etc and update T1707205 if necessary.
- Replace geophone preamps and cables (to fix noise, offset, pinout flip issues).
- Add more mass to IP to get lower frequency.
- Adjust all GAS filters to near mid-range (using keystone mass for F0 as much as possible, and FR+LVDT for SF and BF).
- Mark: 12/24 - 1/4.
- Hirata-san: 12/24 - 1/4.
- Fabian: 12/31 - 1/4
- Enzo: 12/31 - 1/4.
- Mark and Enzo: KAGRA International Workshop in Perugia, 2/14-16.
- Terrence: back at Kamioka from 1/7.