= ISC Meeting on 2017/7/3 14:00 - 15:00 =
Participants: Hiro Yamamoto, Arai, Kokeyama, Akutsu, Aso, Izumi, Michimura (eZuce meeting)

=== Next meeting ===
2017/7/31 14:00 - 15:00 (July 17 is a holiday)

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

== Minutes ==
 * Vibration from heat links
  * information also needed for WAB

 * OMC suspension
  * frame resonant frequency should be fixed based on vibration isolation requirements
  * frame should be made like Bosch frame (screws screwed in the direction of pillars are bad!)
  * flipped OMC is inconvenient for alignment
  * put beam dumps as much as possible on OMC
  * Somiya and Kasuya visit Koji's OMC lab (Amaldi at Caltech)

 * DC QPD holder
  * 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

 * bKAGRA sensitivity update
  * torsion modes of blade springs could complicate the suspension thermal noise

== Agenda ==
 * 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.

 * OFI and OMC status? [Somiya]
  * look for OFI with larger aperture [Somiya]
  * output optics task sharing status?
  * OMC baseplate issue?
  * design review on June 26 at Titech ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6853|JGW-G1706853]],[[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6854|JGW-G1706854]]), layout review on July 3 {*}
   * OMC suspension (Flipped optics or not? 3 or 4 wires? 2 or 1 DC PD? How to damp and actuate pendulum?), OFI suspension

 * Actuator noise modeling [Michimura,Miyamoto] ([[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3453|JGW-T1503453]])
  * Updated magnet size for cryopayload marionette ([[KAGRA/Subgroups/VIS/ActuatorDesign|ActuatorDesign wiki]])
  * Updated lock acquisition section to derive velocity requirements for suspensions (see [[KAGRA/subgroup/ifo/MIF/Minutes20170410|ISC Meeting minutes 20170410]]) [Michimura]
  * Magnetic noise calculation updated ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=4459|JGW-T1504459]]) [Shimoda] {*}
   * Added torque effect on magnets
  * Needs to implement frequency noise, but FSS modeling with ALS is complicated [student!]
  * Discuss mirror vibration from heat link {*}
   * Ochi is measuring vibration of cryo-shield, which is different cryo system from the mirror
   * Yamada is measuring spring constant of heat links
   * Miyamoto has the cryopayload suspension model

 * bKAGRA Phase 1 initial alignment / commissioning plan [Michimura]: [[http://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=5692|JGW-T1605692]]
  * Fixed mirrors for AS port (including SR2)
  * Some comments from the Chief Meeting
   * Revised schedule seems compatible with PRMI. Why not?
    * PRMI is an option after achieving the Phase 1 goal, if it doesn't delay the final bKAGRA [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=5595|JGW-T1605595]]
   * Initial alignment does not interfere with ITM Type-A installation work?
   * Evacuation of IXC/IYC compatible with Type-A installation work?
   * Baffle PDs for initial alignment in vacuum
    * confirmed with Akutsu that he is thinking of putting PDs on narrow angle baffles
    * vibration isolation for baffle PDs necessary?
    * possibility of seeing beams with Tcam

 * IR/green steering mirrors [Michimura] (see [kagra-isc 01649])
  * for POP/POS and green steering in PR2/SR2 chamber, needs picomotors and ~40 cm pedestals
  * need this by the end of August 2017 (after PR2 installation on June, before IR initial alignment starts on September)
  * proposed mirror specs
   * HR reflectivity: more than 99% for both 1064nm and 532nm
   * AR refectivity: less than 0.3 % for 1064nm, similar for 532nm
   * incient angle: 20-45 deg, s-polarization
   * radius of curvature: flat
    * should be something like: larger than *** km {*}
   * size: 2-inch
   * wedge: 1 deg
   * substrate: Fused Silica
   * surface quality: λ/20, 0.1 nm rms roughness

 * DC QPD holder [Michimura] {*}
  * we are using oplev QPD ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=2411|JGW-D1402411]]) for ISC DC QPD
  * we will need QPD mounts for them, just like oplev QPD mount ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=3562|JGW-D1503562]])
  * 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

 * bKAGRA sensitivity update {*}
  * quantum noise calculation was wrong (pointed out by Haino)
   * sign mistake, very slight effect on sensitivity
  * suspension thermal noise calculation was wrong (pointed out by Komori)
   * strange behavior with respect to sapphire blade resonant frequency
   * temperature gradient treatment was wrong
  * update on sapphire mirror temperature
   * ITM substrate absorption turned out to be ~30 ppm/cm ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6429|JGW-G1706429]])
   * 80 ppm/cm was assumed in the last update, so mirror temperature was 23.1 K ([[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=5698|JGW-G1605698]])
  * currently re-calculating the thermal noise, with non-equilibrium condition and less substrate absorption [Komori, Somiya, Ballmer, Michimura]

See [[KAGRA/subgroup/ifo/MIF/Minutes20170410|this page]] for other agendas.