ISC Meeting on 2020/06/15 12:30 - 14:00
Participants: Haoyu Wang, Eleonora Caposcasa, Hiro Yamamoto, Keiko Kokeyama, Kentaro Somiya, Kiwamu Izumi, Koji Arai, Koji Nagano, Masayuki Nakano, Osamu Miyakawa, Shinji Miyoki, Ryutaro Takahashi, Tomotada Akutsu, Yoichi Aso, Yubo Ma, Takaaki Yokozawa, Yuta Michimura
Zoom meeting: https://zoom.us/j/7631499341
Next meeting
TBD
Minutes
The latest KAGRA FINESSE file lives in https://granite.phys.s.u-tokyo.ac.jp/svn/LCGT/trunk/mif/Finesse_Simulations/
- Calculations done by Somiya and Hiro show that the effect from BS thermal lensing is smaller than the effect from BS maps, which is smaller than ITM maps
- Power at BS for bKAGRA design (670 W) is smaller than that for aLIGO design (5 kW ish?)
- Bifrefringence simulation with FINESSE needs more work.
- Two-world approach for DRMI could be OK, but some more tricks will be necessary for doing simulation with arms.
[A/I] Organize another meeting to discuss how to simulate s-p coupled interferometer [Michimura]
[A/I] Ask FINESSE developers for the possibility of modifying FINESSE to handle polarizations [Haoyu]
[A/I] Send current model with maps to Haoyu [Kokeyama]
- Lack of manpower for simulating LSC
- No one in KAGRA can run Optickle LSC right now
- LSC sensing matrix from FINESSE seems strange
- Probably FINESSE simulation is more urgent considering HOM effects are large with current ITMs
[A/I] Find people to work on LSC by Optickle or FINESSE [Michimura]
- Measurements at the site
- LSC sensing matrix measurement was done. Needs calibration.
- RF transimpedance measurement can be done with shot noise limited light
- DC power can be estimated with DC transimpedance and shot noise limited DC output
- RF transimpedance can be measured by measuring the shot noise dependence on input DC power
Measured RF PD transimpedance also summarized in JGW-E1910675
- Swept sine measurement for intensity noise coupling was done, but couldn't measure the coupling below ~100 Hz due to too much noise
- Measurements to be done this week
- PRC length
- Schnupp asymmetry (measurement done a while ago was for 3 km Michelson with more noise)
- etc.
- Others
- Is it OK to keep SVN public?
Agenda
- New members
Haoyu Wang (University of Shanghai for Science and Technology) JGW-G2011697
Yubo Ma (Shanxi Datong University) JGW-G2011696
- Useful links to know KAGRA interferometer design and status
List of optical parameters OptParam
MIF Design document JGW-T1200913
Interferometer design paper Phys. Rev. D 88, 043007 (2013)
Latest KAGRA status paper arXiv:2005.05574
Summary of measurements related to the interferometer so far Minutes20200309
O4 schedule JGW-E1809209
- Interferometer issues which require simulation studies
ITMs have different transmission (ITMX: 0.444 % ITMY: 0.479%) JGW-T1910352
ITMs have inhomogeneity Phys. Rev. D 100, 082005 (2019)
ITMs have inhomogeneous birefringence JGW-G1910369, JGW-G1910388, JGW-T2011633
So far no success in locking DRFPMI JGW-G2011693
WFS not working well JGW-G2011687
Laser intensity and frequency noise couplings are too high JGW-T2011662
Carrier power recycling gain for PRMI (roughly 3) and PRFPMI (11-12) are too different, which could be due to the Lawrence effect JGW-T2011633
- Status of simulation activities
LSC simulations with Optickle originally by Yoichi Aso https://granite.phys.s.u-tokyo.ac.jp/svn/LCGT/trunk/mif/IFOmodel
Used for designing the interferometer, and deriving requirements JGW-T1200913
Simulations for O3 by Yutaro Enomoto JGW-T1910341
Mach-Zehnder modulator simulations by Kohei Yamamoto Classical and Quantum Gravity 36, 205009 (2019)
ASC simulations with Optickle originally by Yuta Michimura https://granite.phys.s.u-tokyo.ac.jp/svn/LCGT/trunk/mif/ASC-Optickle
Used for designing the interferometer JGW-T1200913
Simulations for O3 by Yuta Michimura JGW-T1910359
FINESSE model originally by Kentaro Somiya JGW-T1402434 (any updated version?)
Used for OMC design JGW-T1808043, Optical Review 22, 149-152 (2015), J. Phys.: Conf. Ser. 957, 012009 (2018)
ITM inhomogeneity effects Phys. Rev. D 100, 082005 (2019)
Also being used for simulating birefringence effects by Keiko Kokeyama JGW-G1910461, JGW-T1910380
- Parametric instability by Kiichi Kaihotsu, Kazuhiro Yamamoto
Activities in University of Toyama using COMSOL JGW-E1910382
- Thermal lensing by Kentaro Somiya ?
- Thermal lensing in cryogenic sapphire mirrors should be small (orders of magnitude smaller than room temperature fused silica)
- Thermal lensing in room temperature fused silica BS needs investigation
- Rough estimation by Hiroaki Yamamoto shows it is OK-ish, comparing the result with aLIGO
- Further investigation necessary (also for future higher power)
- Simulation activities necessary
- LSC and ASC simulations with current ITMs and current interferometer setup
- Especially LSC simulations not done for PRFPMI and DRMI, and 3f locking
- Compare measured LSC and ASC sensing matrices with simulations
- Compare measured recycling gain (for carrier and sidebands) with simulations
- Compare measured AS mode content with simulations
- Compare measured MICH/PRCL/SRCL controls noise coupling with simulations
- Compare measured intensity/frequency noise coupling with simulations
- Thermal lensing in BS
- LSC and ASC simulations with current ITMs and current interferometer setup
- Measurements necessary to do simulation work
- PRC (SRC) length and Gouy phase
- Schnupp asymmetry
- modulation depth (arm cavity scan)
- arm cavity length (arm cavity scan)
arm cavity round-trip loss measurement with birefringence effect correctly taken into account (with PBS at POP/POS and TRX/TRY) JGW-T2011633
- Power recycling gain for carrier and sidebands
- Throughput from IMC output to AS RF, OMC DC, REFL, POP, TRX, TRY
- Measurements necessary to compare the result with simulation
- frequency/intensity noise coupling, down to ~10 Hz
- Measure power recycling gain for sidebands (POP 2f with FPMI locked and PRFPMI locked)
- DRFPMI LSC and ASC sensing matrix
- MICH/PRCL/SRCL to DARM coupling
- Measure MICH contrast defect with MICH locked and FPMI locked
- OMC cavity scan to scan mode content of AS beam
https://docs.google.com/spreadsheets/d/1w4q8OvX9E6nkYSgshLYLoZH5yvQXHvGmL1agux8ztx0/edit#gid=0
- Type-A, B, Bp actuation efficiency measurements (for actuator noise)