= ISC Meeting on 2017/10/23 14:00 - 15:00 =
Participants: Hirose, Kohei Yamamoto, Hiro Yamamoto, Koji Arai, Somiya, Enomoto, Koji Nagano, Aso, Michimura

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

=== Next meeting ===
2017/11/6 14:00 - 15:00

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

== Minutes ==
 * SRM reflectivity for early phase of bKAGRA 
  * Sensitivity calculations [Enomoto] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7078|JGW-G1707078]]
   * 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] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7296|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)

 * Requirements for RF AM generation [Kohei Yamamoto] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7309|JGW-G1707309]]
  * 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]

== Agenda ==
 * bKAGRA sensitivity update [Komori] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7038|JGW-T1707038]]
  * approved, and updated [[KAGRA|Wiki]] and [[http://gwcenter.icrr.u-tokyo.ac.jp/en/researcher/parameter|HP]]

 * bKAGRA Phase 1 [Michimura]
  * initial alignment work starts on Oct 10; see [[KAGRA/Commissioning|Commissioning]] page
  * 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

 * 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
  * 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 (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] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7296|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] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7281|JGW-T1707281]] {*}
  * 60ppm scattering, 200ppm coating absorption for ETMX
  * 287ppm scattering, 41ppm coating absorption for ETMY
  * is this compatible with RSE?

 * 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?

 * 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]] {*}
   * 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]
  * 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.