= ISC Meeting on 2018/5/22 14:00 - 15:00 =
Participants: Kiwamu Izumi, Koji Arai, Keiko Kokeyama, Eiichi Hirose, Koji Nagano, Yutaro Enomoto, Yuta Michimura

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

=== Next meeting ===
TBD (We might have ALS meeting on 6/4)<<BR>>
2018/6/18 (Mon) 14:00-15:00 (JST)<<BR>>
2018/6/18 (Mon) 07:00-08:00 (CEST) (Michimura at Virgo from June 4 to August 17)<<BR>>
2018/6/17 (Sun) 22:00-23:00 (PDT)<<BR>>
https://www.timeanddate.com/worldclock/meetingtime.html?day=18&month=6&year=2018&p1=248&p2=4399&p3=137&iv=0

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

== Minutes ==
 * New subchief: Kiwamu Izumi (green lock system)
  * Budget for green will be independent of main MIF budget

 * Summary of Phase-1 measurements [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8217|JGW-G1808217]] [Enomoto]
  * Noisebudget includes angular control noise from BS and PR2 oplev control (no oplev control for PR3 was applied because of glitches)
  * To measure the suspension TFs at low frequencies, white noise injection is better to resolve peaks.
  * DC value of actuator TF should have been measured.
  * Ask Miyamoto to write klog on ETMX,ETMY actuator efficiency
  * Schnupp asymmetry measurement was not so precise because Michelson contrast changed very much and there was suspected spurious coupling from IMC length to MICH signal.

 * KAGRA configuration for joining O3
  * There was suggestion from many people that PRFPMI option should not be deleted.
  * We have set FPMI as a minimum goal, but we this does not mean we cannot try PRFPMI.

 * bKAGRA RF cables [Michimura]
  * ordered 30m SMA cables on Apr 18, arrived on May 9, Hirata-san et al. brought them to Teion Kikaishitsu on May 11.

 * 2inch SRMs (70% and blank) are already arrived and stored at ICRR [Hirose]

== Agenda ==
 * New subchief: Kiwamu Izumi (green lock system) {*}

 * Summary of Phase-1 measurements [[KAGRA/Commissioning/Phase1/Operation/MeasurementsSummary|MeasurementsSummary wiki]] {*}
  * Slides for GWADW2018 [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8217|JGW-G1808217]] [Enomoto]

 * Report from GWDAW2018, F2F at Osaka {*}

 * Main topics for Phase-2 [Michimura] {*}
  * Fix initial alignment scheme for full IFO
  * Finalize ALS scheme and RF AM generation scheme and finalize lock acquisition scheme
  * ISC modeling, especially ASC modeling, for intermediate IFO configurations
  * Cabling schematic
  * In-vacuum RF PD and RF QPD
  * Readout DC PDs and OMC
  * Design output optics on optical tables

 * KAGRA configuration for joining O3 [Michimura] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8172|JGW-T1808172]]
  * Conclusion: We will keep RSE scenario. But we might switch to FPMI at some points (every end of Sep/2018, Dec/2018 and Mar/2019) if preparation is judged as insufficient for RSE.
  * Possibility of PRFPMI operation? {*}
   * Change f1 sideband frequency?
   * Use pick-off of BS for MICH signal?

 * bKAGRA RF cables [Michimura] {*}
  * ordered 30m SMA cables on Apr 18, arrived on May 9, Hirata-san et al. brought them to Teion Kikaishitsu on May 11.

 * SRM doughnut metal mass status? {*}
  * 2inch SRM arrived?

 * RF generation scheme [Michimura]
  * f1 = 3/8*f2, f3 = 10/8*f2
  * we need 2*f1, 2*f2, f3-f1, f3-f2 as well
  * use harmonics generator (x3, x5, x6, x7, x8, x10, x16 for f2/8 = 5.62698725 MHz (FSR for IMC))
   * Wenzel specsheet [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8028|JGW-D1808028]] {*}
    * ordered two units on Apr 21 (takes 14 weeks)
  * Usage of 6 Agilent N5181B [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6762|JGW-T1706762]] {*}
   * Current use: fFSS, fIMC, ISS AOM, f1, fALSX at UToyama, spare at Ando-Lab
   * Possible use in near future: fPMC, fFSS, fIMC, fALSX, fALSY, ALS AOM, ISS AOM, f1, f2, f3
    * buy new RF signal generators for fPMC and fFSS?
   * Final use: fPMC, fFSS, fIMC, fALSX, fALSY, f1/f2/f3 with harmonics generator
    * Use AOM drivers for ALS AOM and ISS AOM

 * RF generation using Mach-Zehnder interferometer [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]] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8029|JGW-G1808029]] {*}
  * simulation on imperfections (MZ arm asymmetry, MZ lock, EOM phase difference control etc.)
  * calculate requirements on MZI displacement, EOM modulation phase difference, EOM imbalance
  * Requirements derived from full Optickle simulation and those derived from transfer function between displacement of MZI and sideband power kind of matched after implementing RAM into calculation for the latter. However, we need more investigation on the following issues:
   * Modulation depth for RAM generating EOM changes the requirement.
   * Spectrum shapes of the requirements for mid-fringe do not match. Maybe coming from accuracy of the mid-fringe?
   * Unknown frequency response of the transfer function from the displacement of MZI and sideband power
   * Check if caluculated RF oscillator amplitude noise is relative one or not with simple Optickle model
  * calculations for requirements on delay line lock displacement noise, parallel EOM MZ lock displacement noise, EOM modulation phase difference, EOM imbalance on-going
  * Relative f1 PM and f1 AM also needs to be adjusted ([[http://iopscience.iop.org/article/10.1088/0264-9381/31/9/095003/meta|CQG 31, 095003 (2014)]]). Another EOM for f1 or relative amplitude adjuster between two EOMs?
  * 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.
  * Ref: [[https://dcc.ligo.org/LIGO-T040119/public|LIGO-T040119]]
  * MZI implementation starts in May, probably before high power laser installation
  * RF oscillator noise requirements for MZI should also be calculated

 * 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? ([[https://dcc.ligo.org/LIGO-D1002969/public|LIGO-D1002969]])
   * operational frequency range of IQ demodulator: upto 100 MHz
  * 3f
   * needs RF differential frequency generator (or harmonics generator) for 39.39 MHz (f3-f1) and 11.25 MHz (f3-f2), RF PD for those frequencies.
   * needs Mach-Zehnder modulation

 * ALS configuration [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7416|JGW-E1707416]] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=788|JGW-T1200788]] [[KAGRA/Subgroups/IOO/ALS|ALS Wiki]]
  * where to put a frequency offset: arm length or PLL offset [Enomoto] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=7726|JGW-L1807726]]
  * fiber selection meeting on March 23  {*}
   * determined to use end-cap for both
   * there was a suggestion to lay IR fibers also

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

 * 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.