ISC Meeting on 2020/07/06 13:30 - 14:00
Participants:
Zoom meeting: https://zoom.us/j/5045179604
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)