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

Participants:

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

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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.
- 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.
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 for 39.39 MHz (f3-f1) and 11.25 MHz (f3-f2), RF PD for those frequencies.
  - needs Mach-Zehnder modulation

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.