= ISC Meeting on 2018/1/15 14:00 - 15:00 =
Participants: Kohei Yamamoto, Koji Nagano, Yutaro Enomoto, Koji Arai, Yoichi Aso, Yuta Michimura, Kentaro Somiya, Kiwamu Izumi, Keiko Kokeyama, Osamu Miyakawa

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

=== Next meeting ===
2018/1/29 14:00 - 15:00

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

== Minutes ==
 * Calculations for requirements on Mach-Zehnder interferometer for RF AM generation [Kohei Yamamoto] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7655|JGW-G1807655]] {*}
  * Requirements derived from full Optickle simulation and those derived from transfer function between displacement of MZI and sideband power do not match.
  * The transfer function seems funny. Might be mistake in the Optickle code (e.g. unnecessary mechanical response for MZI mirrors).
  * A/I: upload the code on SVN. RF AM camp in Ando group on Jan 18.

 * bKAGRA cables [Michimura] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7586|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

== Agenda ==
 * KAGRA configuration for early phase of bKAGRA [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7334|JGW-T1707334]] {*}
  * SRM reflectivity
   * Mirror ordered
   * Black coating for metal mass?
  * ITM asymmetry [Enomoto] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7565|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] [[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

 * bKAGRA cables [Michimura] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7586|JGW-T1707586]] {*}
  * cable lengths depend on the position of ISC racks
  * discussion in the week of Jan 22?

 * 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 [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7309|JGW-G1707309]] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7655|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]
  * 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.

----

 * 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 [[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]
   * 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 [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7051|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 [[KAGRA/subgroup/ifo/MIF/Minutes20170410|this page]] for other agendas.