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 ??

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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.