ISC Meeting on 2017/7/3 14:00 - 15:00

Participants: (eZuce meeting)

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2017/7/31 14:00 - 15:00 (July 17 is a holiday)

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Agenda

• 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
    • 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
  • 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.
• OFI and OMC status? [Somiya]
  • look for OFI with larger aperture [Somiya]
  • output optics task sharing status?
  • OMC baseplate issue?

  • design review on June 26 at Titech (JGW-G1706853,JGW-G1706854), layout review on July 3

    • OMC suspension (Flipped optics or not? 3 or 4 wires? 2 or 1 DC PD? How to damp and actuate pendulum?), OFI suspension

• Actuator noise modeling [Michimura,Miyamoto] (JGW-T1503453)

  • Updated magnet size for cryopayload marionette (ActuatorDesign wiki)

  • Updated lock acquisition section to derive velocity requirements for suspensions (see ISC Meeting minutes 20170410) [Michimura]

  • Magnetic noise calculation updated (JGW-T1504459) [Shimoda]

    • Added torque effect on magnets
  • Needs to implement frequency noise, but FSS modeling with ALS is complicated [student!]

  • Discuss mirror vibration from heat link

    • Ochi is measuring vibration of cryo-shield, which is different cryo system from the mirror
    • Yamada is measuring spring constant of heat links
    • Miyamoto has the cryopayload suspension model

• bKAGRA Phase 1 initial alignment / commissioning plan [Michimura]: JGW-T1605692

  • Fixed mirrors for AS port (including SR2)
  • Some comments from the Chief Meeting
    • Revised schedule seems compatible with PRMI. Why not?

      • PRMI is an option after achieving the Phase 1 goal, if it doesn't delay the final bKAGRA JGW-T1605595

    • Initial alignment does not interfere with ITM Type-A installation work?
    • Evacuation of IXC/IYC compatible with Type-A installation work?
    • Baffle PDs for initial alignment in vacuum
      • confirmed with Akutsu that he is thinking of putting PDs on narrow angle baffles
      • vibration isolation for baffle PDs necessary?
      • possibility of seeing beams with Tcam
• IR/green steering mirrors [Michimura] (see [kagra-isc 01649])
  • for POP/POS and green steering in PR2/SR2 chamber, needs picomotors and ~40 cm pedestals
  • need this by the end of August 2017 (after PR2 installation on June, before IR initial alignment starts on September)
  • proposed mirror specs
    • HR reflectivity: more than 99% for both 1064nm and 532nm
    • AR refectivity: less than 0.3 % for 1064nm, similar for 532nm
    • incient angle: 20-45 deg, s-polarization
    • radius of curvature: flat

      • should be something like: larger than *** km

    • size: 2-inch
    • wedge: 1 deg
    • substrate: Fused Silica
    • surface quality: λ/20, 0.1 nm rms roughness

• DC QPD holder [Michimura]

  • we are using oplev QPD (JGW-D1402411) for ISC DC QPD

  • we will need QPD mounts for them, just like oplev QPD mount (JGW-D1503562)

  • 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

See this page for other agendas.