= ISC Meeting on 2017/9/25 14:20 - 15:00 =
Participants: Enomoto, Koji Nagano, Kokeyama, Somiya, Michimura, Koji Arai, Miyakawa

=== Next meeting ===
2017/10/23 14:00 - 15:00

[[LCGT/subgroup/ifo/ISC/Meetings|back to Meetings page]]

== Minutes ==
 * SRM reflectivity for early phase of bKAGRA [Enomoto] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7078|JGW-G1707078]]
  * sensitivity with 50% SRM will be similar to that wit 85% SRM when excess noise at low frequency is x8 aLIGO O1
   * therefore, 50% SRM is OK in terms of excess noise
  * sensitivity for misaligning or adding extra loss with 85% SRM is worse than that for 0% SRM
  * A/Is
   * make a table what are necessary to reach 40 Mpc with different SRM reflectivity [Enomoto]
   * check LSC 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
   * ask Hirose-san for 2-inch SRM [Michimura]
   * make an overall budget/manpower/schedule estimate to reach 40 Mpc with different SRM reflectivity [Michimura]

== Agenda ==
 * bKAGRA sensitivity update [Komori] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7038|JGW-T1707038]]
  * basically approved at EO on Sept 20

 * bKAGRA Phase 1 [Michimura]
  * initial alignment work starts on Oct 10; see [[KAGRA/Subgroups/MIF/Commissioning|MIF Commissioning]] page
  * no AS optics for Phase 1, instead use reflection REFL beam from PRM
  * we have to prepare REFL optics

 * bKAGRA Phase 2 schedule [Michimura] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7079|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] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7078|JGW-G1707078]]
  * 50% reflectivity is better than default (85%) when input power is below ~30 W
  * A/Is
   * LSC and ASC check
   * excess noise at low frequency
   * schedule, budget, manpower
   * 2inch SRM quality
   * check how bad is PRFPMI with 85% misaligned or RSE with lossy SRC

 * IMMT1 and IMMT2 transmission [Michimura, Takeda]
  * IMMT2 transmission optics are too much squeezed

 * IR/green steering mirrors [Michimura]
  * will arrive at Mozumi on Sept 6
  * pedestals, mirror mounts

 * DC QPD holder [Michimura] {*}
  * beam height should be 4inch to use similar mount, with small modification of spacer (instead of 3inch in [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2607|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]

 * PSL EOM Layout re-consideration [Enomoto] ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6748|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 ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=5611|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.

 * Actuator noise modeling [Michimura,Miyamoto] ([[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3453|JGW-T1503453]])
  * Summarized in the paper [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7051|JGW-P1707051]]
   * waiting for Type-A seismic transfer function update [Okutomi]
  * 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 [[KAGRA/subgroup/ifo/MIF/Minutes20170410|this page]] for other agendas.