ISC Meeting on 2020/07/06 13:30 - 14:30

Participants: Kenta Tanaka, Shinji Miyoki, Haoyu Wang, Eleonora Caposaca, Kiwamu Izumi, Koji Nagano, Masayuki Nakano, Matteo Leonardi, Osamu Miyakawa, Ryutaro Takahashi, Kentaro Somiya, Tomotada Akutsu, Yoichi Aso, Yuta Michimura

Zoom meeting: https://zoom.us/j/5045179604

Your time zone: https://www.timeanddate.com/worldclock/fixedtime.html?iso=20200706T0430

Next meeting

When necessary (New meeting slot: bi-weekly Mondays, from 13:00 JST)

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Minutes

• Video record of the meeting: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11793

• Summary of current measurements so far
  • LSC sensing matrix, measurements vs simulation
    • The parameter choice of "BRSE_SDMR1_17_45" is OK for the Optickle simulation.
      • SDMR1 means single demodulation, using REFL_1I for CARM.
    • POP17Q (MICH error signal) seems to have too much DARM contribution.
      • Although DARM displacement is much smaller than MICH displacement and may be negligible, MICH feedforword would spoil DARM if DARM to MICH coupling is too large
      • DARM excitation was done by injecting signal at DARM error point, when DARM was fed back to both ETMs

    • A/I: Sensing matrix re-measurement with

      • Correct CARM calibration
      • Feedforword off (probably already done with FF off, but need to double check)
      • Measurement for both I-phase and Q-phase
  • Schnupp asymmetry

    • Result from time of flight measurement (3.36(1) m, https://klog.icrr.u-tokyo.ac.jp/osl/?r=14575) and that from laser frequency modulation measurement (0.56 m https://klog.icrr.u-tokyo.ac.jp/osl/?r=14541) are inconsistent

      • There might be an error in BS calibration, laser frequency calibration and/or calculations
        • ETM calibration starting from free-swinging Michelson and Pcal ETM calibration seems to be consistent
        • Laser frequency calibration using ALS AOM and Pcal ETM calibration seems to be consistent
        • Calculations are confirmed independently by Keiko and Masayuki

      • A/I Check the calculations again

  • PRC length measurements
    • Time of flight measurement would be possible if you use AS beam

    • A/I PRY length measurement to be done once IFO is recovered

  • OMC scan to see mode content of AS beam

    • Carrier and f1 HOM3 mode seems to be overlapped https://klog.icrr.u-tokyo.ac.jp/osl/uploads/14691_20200705054303_omcmodes.pdf

• New ISC member

  • Kenta Tanaka (ICRR) -> added to kagra-isc mailing list

Agenda

• RECORD THE MEETING
• Summary of current measurements so far
  • LSC sensing matrix, measurements vs simulation

    • Optickle simulation: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11767

      • Parameter choice of "BRSE_SDMR1_17_45" OK?

    • Measurements: https://klog.icrr.u-tokyo.ac.jp/osl/?r=14515, https://klog.icrr.u-tokyo.ac.jp/osl/?r=14593

  • Schnupp asymmetry measurements

    • Time of flight measurement successful https://klog.icrr.u-tokyo.ac.jp/osl/?r=14575

  • PRC length measurements

    • PRY length: 68.28 m with the error of roughly 1 m (designed: 64.926 m) https://klog.icrr.u-tokyo.ac.jp/osl/index.php?r=14555

    • PRX length: about 68 m (designed: 68.2559 m) https://klog.icrr.u-tokyo.ac.jp/osl/?r=14633

    • Actuator efficiency inconsistent between measurements?
  • OMC scan to see mode content of AS beam

    • Summary http://klog.icrr.u-tokyo.ac.jp/osl/?r=14696

    • carrier and f1 3rd mode is overlapped? http://klog.icrr.u-tokyo.ac.jp/osl/?r=14620

  • Frequency noise coupling

    • https://klog.icrr.u-tokyo.ac.jp/osl/?r=14614

  • Arm cavity round-trip loss measurement with birefringence effect correctly taken into account

    • P-pol and S-pol PDs placed on POS table https://klog.icrr.u-tokyo.ac.jp/osl/?r=14622

• Birefringence simulations with FINESSE
  • Any volunteer to add polarization to FINESSE code?
  • "directional beamsplitter" could be used to simulate DRFPMI with FINESSE using s/p two-world approach [Haoyu]

    • https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11792

• New ISC meeting slot?
  • Bi-weekly SEO and Chief meeting on Modays, from 15:00 JST
  • How about bi-weekly Mondays 13:00 JST (before chief meetings)

Copy from previous meeting

• 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 (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

    • LSC https://klog.icrr.u-tokyo.ac.jp/osl/?r=14515

  • 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)