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• Minutes20180115

ISC Meeting on 2018/1/15 14:00 - 15:00

Participants: Kohei Yamamoto, Koji Nagano, Yutaro Enomoto, Koji Arai, Yoichi Aso, Yuta Michimura, Kentaro Somiya, Kiwamu Izumi, Keiko Kokeyama, Osamu Miyakawa

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

Next meeting

2018/1/29 14:00 - 15:00

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Minutes

• Calculations for requirements on Mach-Zehnder interferometer for RF AM generation [Kohei Yamamoto] JGW-G1807655

  • Requirements derived from full Optickle simulation and those derived from transfer function between displacement of MZI and sideband power do not match.
  • The transfer function seems funny. Might be mistake in the Optickle code (e.g. unnecessary mechanical response for MZI mirrors).
  • A/I: upload the code on SVN. RF AM camp in Ando group on Jan 18.

• bKAGRA cables [Michimura] JGW-T1707586

  • we have to soon purchase RF cables, but cable lengths depend on the position of ISC racks
  • discussion and cable length measurements in the week of Jan 22

Agenda

• KAGRA configuration for early phase of bKAGRA JGW-T1707334

  • SRM reflectivity
    • Mirror ordered
    • Black coating for metal mass?

  • ITM asymmetry [Enomoto] JGW-T1707565

    • ITM asymmetry is OK for early stages, but asymmetric ITMs cannot be used for achieving design sensitivity
• 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

• 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

• bKAGRA cables [Michimura] JGW-T1707586

  • cable lengths depend on the position of ISC racks
  • discussion in the week of Jan 22?

• 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 JGW-G1807655

    • 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.

• 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?
• 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.