ISC Meeting on 2020/06/15 12:30 - 13:30

Participants:

Zoom meeting: https://zoom.us/j/6676627462

Time: https://www.timeanddate.com/worldclock/meetingdetails.html?year=2020&month=6&day=15&hour=3&min=30&sec=0&p1=248&p2=237&p3=4399&p4=137

Next meeting

TBD

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Minutes

Agenda

• 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
  • 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
• Measurements necessary to do simulation work
  • PRC 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

  • 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