ISC Meeting on 2017/11/6 14:00 - 15:00

Participants: Aso, Enomoto, Hiro Yamamoto, Koji Arai, Koji Nagano, Hirose, Miyakawa, Kokeyama, Izumi, Somiya, Michimura

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

Next meeting

2017/11/20 14:00 - 15:00

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Minutes

KAGRA configuration for early phase of bKAGRA
- SRM reflectivity
  - Metal mass design [Aso]
    - design almost complete
    - estimate says roughly 15man-yen, 1-2 months
    - glue 2-inch SRM onto a ring, and fix the ring onto doughnut mass with screws
    - A/I: upload the design to JGWDoc by Nov 13 [Aso]
  - Sensitivity calculations [Enomoto] JGW-G1707078
    - made noise vs input power plot necessary to achieve ~6 event/year (~40 Mpc for BNS, ~580 Mpc for BBH30)
    - MICH coupling is worse with lower reflectivity SRM
    - suspension thermal noise will be 2 orders of magnitude worse in room temperature case [by Somiya]
    - A/I: somehow compare with AdV　[Enomoto]
    - A/I: laser intensity/frequency noise coupling [Izumi]
  - 2-inch SRM estimate [Michimura,Hirose]
    - Asked to 2 companies. Roughly ~100man-yen.
    - We want it to arrive at least before the final phase of SRM installation (August 2018)
- PRFPMI or RSE [Michimura]
  - PRFPMI with either spare ETM or real ETM will delay the overall schedule to make KAGRA compatible with GW detection
  - What is our target? Joining O3 or first detection ASAP?
  - We also have to consider what to do if we miss O3. It's harder to detect GW with single detector. Global coordination necessary.
  - Possibility of parallel work for joining O3?
  - A/I: sensitivity calculations for PRFPMI with spare ETM [Enomoto,Michimura]

Agenda

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
SRM reflectivity for early phase of bKAGRA [Enomoto] JGW-G1707078
- Sensitivity calculations [Enomoto]
  - Made excess noise vs input power plot necessary to achieve BNS range of 40 Mpc
    - SRM reflectivity of 70% seems least demanding in terms of excess noise and input power
    - A/I: redo calculation for BBH range (with estimate of event rate) [Enomoto]
  - LSC noise coupling calculation on going
    - UGF for auxiliary dof can be lower than 50 Hz [by Izumi]
    - MICH error signal from POP instead of MICH might be better considering phase flipping [by Izumi]
- SRM surface quality [Hirose] JGW-T1707296
  - MCe-level quality SRM will produce ~52 ppm (this estimate is based on surface quality without coating; coating could increase loss by x2 to x4)
  - A/I: SRM loss requirement for low reflectivity SRM [Michimura,Enomoto]
- SRM metal mass [Aso]
  - overall mechanical components will cost roughly ~1M JPY [Aso]
  - composite mass could create unwanted resonance (at ~3 kHz in aLIGO case, with PEEK screw)
- sensitivity for misaligning or adding extra loss with 85% SRM is worse than that for 0% SRM
- A/Is
  - check LSC (and ASC) with different SRM reflectivity and incident power [Enomoto]
  - make a budget/manpower/schedule plan for SRM suspension with 2-inch mirror holder [Aso]
    - since there is already a BS dummy metal mirror suspension design, making similar system for SRM should be easy
  - 2-inch SRM [Michimura, Hirose]
    - asking some companies for estimate
    - loss function estimate [Hirose] JGW-T1707296
  - make an overall budget/manpower/schedule estimate to reach 40 Mpc with different SRM reflectivity [Michimura]
bKAGRA Phase 1 spare ETM quality [Hirose,Michimura] JGW-T1707281
- 60ppm scattering, 200ppm coating absorption for ETMX
- 287ppm scattering, 41ppm coating absorption for ETMY
- is this compatible with RSE (and even PRFPMI)?
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.