ISC Meeting on 2017/11/20 14:00 - 15:00

Participants: Yutaro Enomoto, Koji Arai, Koji Nagano, Eiichi Hirose, Kentaro Somiya, Yoichi Aso, Hiro Yamamoto

eZuce meeting: "KAGRA ISC Meeting" in the KEK community.

Next meeting

2018/1/15 14:00 - 15:00 ??

back to Meetings page

Minutes

• SRM reflectivity

  • Reflectivity is decided to be 70% +/- 5% JGW-G1707078

  • Vendor is also decided
    • Continue to seek for reducing RoC error
  • 2-inch mirror holder for the metal mass will be black coated, to be bought this JFY
• OMC PD
  • aLIGO uses 93% QE PD (without window) in O1, 98% QE PD in O2
  • KAGRA will use 93% QE PD for now, and 98% one in future

Agenda

• KAGRA configuration for early phase of bKAGRA JGW-T1707334

  • SRM reflectivity
    • Approved to go for metal mass SRM. Budget within this JFY
    • Item to be discussed:
      • how much SRM reflectivity
        • also, ASC check
      • mirror company

        • loss function estimate [Hirose] JGW-T1707296

      • black coating for metal mass
  • ETM swap

    • spare ETM quality [Hirose] JGW-T1707281

    • timing depends on final ETMX arrival
• bKAGRA Phase 1 [Michimura]
  • no AS optics for Phase 1, instead use reflection REFL beam from PRM
  • we have to prepare REFL optics
    • height of the beam from PR/BS breadboard will be 380 mm instead of 400 mm?
  • experiments for Phase 1 paper

• bKAGRA Phase 2 schedule [Michimura] JGW-T1707079

  • meeting with SEO on Sept 6
  • Goal: 1 hour lock of cryogenic RSE with RF readout, probably with ASC, no sensitivity goal
  • input laser power not decided
  • when to swap ETM, SRM reflectivity, vacuum
  • schedule adjustment between AS WFS and OMC test necessary
• IMMT1 and IMMT2 transmission [Michimura, Takeda]
  • IMMT2 transmission optics are too much squeezed
• IR/green steering mirrors [Michimura]
  • mirrors arrived, mirror mounts and picomotor driver ordered, pedestals by Akutsu, vacuum cables by Aso
• DC QPD holder [Michimura]

  • beam height should be 4inch to use similar mount, with small modification of spacer (instead of 3inch in JGW-D1402607)

    • RF PD, RF QPD boxes are designed for 4inch beam height
  • stages are not needed for ISC DC QPD

  • design new ones; they can be very simple [-> Michimura?]

  • calibration can be done in different ways
  • put strain relief and anchors for cables to protect QPD board
• OMC and OFI [Somiya]
  • look for OFI with larger aperture [Somiya]
  • DC PD and DC QPD [Michimura]
    • DC PD not available. Look for product with similar specs
    • DC QPD available from RS

• In-vacuum RF PD and RF QPD

  • we need them within 1 year, considering OMC REFL and AS RF

• In-vac beam-dumps

  • required spec?

• PSL EOM Layout re-consideration [Enomoto] (JGW-T1706748)

  • Delay-line length decided to be 2.66 m (instead of 8.88 m)
  • Modulation phase between f1 AM and PM is always aligned (we need this to be aligned)

  • Modulation index needed at each EOM is less than measured maximum index by Uehera (JGW-T1605611)

  • Optickle simulation by Kohei Yamamoto JGW-G1707309

    • simulation on imperfections (MZ arm asymmetry, MZ lock, EOM phase difference control etc.)
    • start with hand calculation, simple setups, and then to full IFO simulation
    • Optickle model basically made, and checked with hand calculations
    • calculations for requirements on delay line lock displacement noise, parallel EOM MZ lock displacement noise, EOM modulation phase difference, EOM imbalance on-going
    • A/I: check phase noise calculations, requirements for f1 AM-PM mixed case [Kohei Yamamoto]
  • Requirement on carrier power loss?
  • Comment from Stefan Ballmer
    • Similar calculation was done in LIGO in the past. Displacement noise requirement for MZ was tough (~1e-14 m/rtHz).
    • Any in-air interferometer suffer from jitter and frequency noise which cannot be suppressed.
• Actuator noise modeling [Michimura,Miyamoto]

  • Summarized in the paper JGW-P1707051

  • Needs to implement frequency noise, but FSS modeling with ALS is complicated [student!]

  • Discuss mirror vibration from heat link

    • Meeting on July 14 [Yamada, Miyamoto, Ushiba, Michimura]

See this page for other agendas.