ISC Meeting for ASC Strategies 2021/08/02 13:00 - 15:00
Participants: Yoichi Aso, Chiaki Hirose, Hiroaki Yamamoto, June Gyu Park, Kentaro Somiya, Kenta Tanaka, Kiwamu Izumi, Shinji Miyoki, Naoki Aritomi, Osamu Miyakawa, Tatafumi Ushiba, Terrence Tak Lun Tsang, Tomotada Akutsu, Yuta Michimura
Zoom meeting: https://zoom.us/j/5045179604
Your time zone: https://www.timeanddate.com/worldclock/fixedtime.html?iso=20210802T0400
Next meeting
2021/08/16 13:00 - 15:00
Minutes
- Why POP WFS was not commissioned well? (Akutsu)
- Not sure. (Terrence)
- Probably it was hard to design the Gouy phase telescope with dirty beam. (Michimura)
- The issues in Xarm ASC commissioning were that we were not sure if it was the best alignment, and we didn't compared the sensing matrix with the simulation (Ushiba)
- We shouldn't take too much time for Xarm, but we should proceed to FPMI (Miyakawa)
- We didn't spend too much time on ASC for O3GK, since it was not required. (Aso)
- We should check POP beam when the vacuum tank is open. (Aso)
- AS WFS was hard because of the dirty beam. SR could help this and this is the reason I'm pushing DR. (Aso)
- Quantitative AS beam comparison between no-recycling, PR, SR should be done.
- DC centering loops for AS was tough because of the dirty beam. Also, the beam shape changed depending on the lock conditions, and feedback signal was somehow too large. (Ushiba)
In aLIGO, DC centering loops were always on when the WFS loops were closed. Try closing DC centering loops after the beam shape gets stable. DC centering loops had UGF higher than that for WFS because beam jitter from tip-tilts (they are used as actuators for the centering loops) were high. (Kiwamu) -> Checking with Jenne and Keita, UGF for DC centering loops now is 4-5 Hz, with a steep cut-off filter.
- For KAGRA, the situation could be different since we don't use tip-tilts. Try starting from low UGF for the centering loops?
- We faced so many mysteries in O3GK. ASC commissioning should be done with a good interferometer condition. (Miyoki)
- Here, "good" means "repeatable," I think. (Michimura)
- In O3GK, we didn't have enough time to compare the measurements with simulations. We were also not sure what are the things to be measured, and how to calibrate the signal to compare the measurement with the simulations. (Ushiba)
- Actually, calibration between each sensor is not so important. Relative amplitudes of the signal are important. (Michimura)
- Good communication with simulation people is necessary.
- FINESSE GUI for ASC is also under development. Should be done within Koyama-kun's Master thesis schedule (within this JFY). (Miyakawa)
- Cross check necessary. Maybe first with Xarm?
- It is important that suspension people accompany with interferometer people. (Miyoki)
- How to check the beam clipping when the center area is in air? There will be a gate valve viewport in between BS and ITMX. (Ushiba)
- Should be OK since the gate valve viewports are made not to clip the main beam. (Michimura)
- But we never checked. (Akutsu)
- What's the latest timeline? Is it reasonable? (Akutsu)
- The latest one is being prepared by Uchiyama-san. (Miyoki)
- 12 week for Xarm sounds reasonable to me. (Michimura)
- Where does the lock stretch requirement of 2 hours come from? (Izumi)
- We've set the 2 hours criteria also for Xarm commissioning and DRMI commissioning for O3. I also think 2 hours is necessary to see the alignment drift. (Michimura)
- Make sure that "2 hours" criteria won't be taken as a serious requirement. (Izumi)
- What is the final goal of this list of goals? Any requirements for the noise performance or duty cycle? (Izumi)
- Hard to answer. It depends on the schedule. (Miyoki)
- My personal goal is to close all the necessary ASC loops for PRFPMI. Assuming this is the final goal, I've listed the goals for each commissioning stage. (Michimura)
- Other requirements like throughput should be added. (Akutsu)
- I will add IMC throughput and the interferometer mode-matching. (Michimura)
- We all agreed to present this list as our list, not as Michimura's personal list, with some modifications.
Agenda
- Summary of what we have achieved so far for ASC
- Why we couldn't implement global controls using WFS and QPDs during the O3GK run?
- What would be the steps necessary to improve the situation?