ISC Meeting on 2018/1/29 14:00 - 15:00

Participants:

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

Next meeting

2018/2/13 (Tue) 14:00 - 15:00 ??

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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

  • 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

• 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]
    • Requirements derived from full Optickle simulation and those derived from transfer function between displacement of MZI and sideband power do not match.
      • A/I: upload the code on SVN. RF AM camp in Ando group on Jan 18.
        • The discrepancy could be from residual AM requirement being pretty strict?
    • Relative f1 PM and f1 AM also needs to be adjusted. Another EOM for f1 or relative amplitude adjuster between two EOMs?
  • 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.

  • Ref: LIGO-T040119

• Three-f or 3f for early phase of bKAGRA ?

  • Three-f (THD)

    • Needs RF tripler for 16.88 MHz and 45 MHz, RF PD for 50.64 MHz (3*f1) and 135 MHz (3*f2). Broadband photo detector? (LIGO-D1002969)

    • operational frequency range of IQ demodulator: upto 100 MHz
  • 3f
    • needs RF differential frequency generator (or harmonics generator) for 39.39 MHz (f3-f1) and 11.25 MHz (f3-f2), RF PD for those frequencies.
    • needs Mach-Zehnder modulation

• ALS configuration JGW-E1707416 JGW-T1200788

  • E8663D with FM option or AOM driver for AOM VCO for green PDH
  • where to put a frequency offset: arm length or PLL offset
• RF generation scheme [Michimura]
  • f1 = 3/8*f2, f3 = 10/8*f2
  • we need 2*f1, 2*f2, f3-f1, f3-f2 as well
  • use harmonics generator (x3, x5, x6, x7, x8, x10, x16 for f2/8 = 5.62698725 MHz (FSR for IMC))
    • seeking for vendors

• 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.