= ISC Meeting on 2018/10/22 14:00 - 15:00 =
Participants: Hiroaki Yamamoto, Koji Nagano, Yutaro Enomoto, Satoshi Tsuchida, Takahiro Miyamoto, Kiwamu Izumi, Yoichi Aso, Osamu Miyakawa, Yuta Michimura

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

=== Next meeting ===
2018/11/5 (Mon) 14:00-15:00 (JST)

https://www.timeanddate.com/worldclock/meetingtime.html?day=5&month=11&year=2018&p1=248&p2=4399&p3=137&iv=0

NOTE: We will use Zoom from the next meeting https://zoom.us/j/6676627462

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

== Minutes ==
 * Main topics for Phase-2 [Michimura]
  * In-vacuum RF PD and RF QPD
   * Laser welding would be tough (resonant circuit cannot be re-tuned)
   * Use similar design to OMC DC PD preamplifier?
  * Design output optics on optical tables
   * A/I: Count how many [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8429|20 mm diameter optics post]] necessary [Michimura] -> DONE

 * RF modulation system
  * Low noise VCO [Enomoto]
   * Two Prototype Low Noise VCO for ALSX and Y assembled, and noise of the one of them was measured. Meets the requirement.
   * We need three 
   * For PLLX and PLLY, Keysight E8663D is used.
    * A/I: Need to develop a code to sweep the frequency.
  * RF source [Enomoto]
   * There are some amplifiers for f1 and f2 EOM (ZHL-1A). They should be replaced.
   * A/I: Make a EOM driver (use spare LNBA-11-23-CK-100-15 and [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6469|Low Noise Power Board for RF Circuit]]?)

 * Common mode servo board [Enomoto]
  * To be finalized and request to AEL soon.
  * We will make 20 boards, and 10 will be assembled as chassis
  * We currently have 5 chassis and used for 1st MZI, IMC, CARM, PLL X, ALS PDHX
  * Needs 4 chassis more soon: 2nd MZI, PLL Y, ALS PDHY, ALS COMM summing node
  * 6 chassis for spare: MZI, IMC, CARM, PLL, PDH, summing node

 * OMC status [Somiya]
  * Electronics status
   * In-vac DC PD amplifier board finalized [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9177|JGW-D1809177]]
   * In-air DC QPD amplifier board arrived (without chassis and interfaces)

 * ITMY inhomogeniety [Somiya]
  * ASC simulation by FINESSE show worse signal when ITMY inhomogeniety is added (a few % degradation in shot noise?)
  * higher order contents, especially odd-order modes are worse
  * But still need to check the Finesse code (alignment loop not closed yet)

 * SRM-M with metal parts [Hirose via email]
  * Will be characterized this week

== Agenda ==
 * Main topics for Phase-2 [Michimura] {*}
  * Fix initial alignment scheme for full IFO
   * Enomoto?
   * For XY arm [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8462|JGW-G1808462]]
  * Finalize ALS scheme and RF AM generation scheme and finalize lock acquisition scheme
   * Enomoto?
  * ISC modeling, especially ASC modeling, for intermediate IFO configurations
   * Tanioka for ASC?
  * Cabling diagram {*}
   * Almost finalized [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8394|JGW-D1808394]]
  * In-vacuum RF PD and RF QPD
   * Izumi will ask LIGO people first. And ask Doi for handling fabrication?
  * Readout DC PDs and OMC
   * In-vac amplifier board made [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9177|JGW-D1809177]] {*}
   * Cabling diagram around OMC [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9012|JGW-G1809012]] {*}
  * Design output optics on optical tables
   * REFL [Aritomi] (almost done, to be ordered) {*}
   * POP [done for green; ? for IR]
   * POS [done for green; ? for IR]
   * TRX/TRY [K. Nagano for both IR and green]
    * TRX designed and assembled [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8962|JGW-T1808962]] {*}
   * AS [??]

 * RF modulation system {*}
  * Three-f or f3
   * Agreed to work on both three-f and f3 for redundancy
   * O3 requirement for MZI was calculated (and met?)
    * A/I: The deadline and when to disassemble MZI (remove some of BSs) when the requirement was not met are to be discussed
   * A/I: How to proceed with broadband PDs for f3-f1/f3-f2? Modify our resonant RF PD? (BB PD also necessary for SPOP (and SPOS))
  * Low noise VCO
   * Assembled [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8968|JGW-D1808968]]
    * performance to be checked?
   * Needs at least 5?
    * FSS AOM (80 MHz), ALSX AOM (80 MHz), ALSY AOM (80 MHz), PLLX (40 MHz), PLLY (40 MHz)
    * Replacing Refcav AOM (currently at 110MHz) will be after ALS AOM
   * In case Low Noise VCO has some trouble or is too noise, we have an option to use PLL VCO
    * Estimate arrived. VCO option will be available within 3 days after order. [Aso]
     * So, we agreed on ordering when we had trouble with Low Noise VCO.
  * RF source
   * Harmonics Generator will arrive in the beggining of Nov (or end of Nov in worst case)
   * We currently have 6 Agilent N5181B, but we need 7 [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=6762|JGW-T1706762]] {*}
    * PMC PDH (15MHz)
    * Refcav PDH (51.75MHz)
    * IMC PDH (13.78MHz)
    * seed for Harmonics Generator
     * if Harmonics Generator delayed, we need 2 for f1 and f2, so we will use one for ALSY PDH
    * ALSX PDH (33MHz) (NOTE that 33MHz for ALSX PDH, not 32MHz)
    * ALSY PDH (32MHz)
     * Not necessary until Yarm commissioning starts (mid-Nov?)
    * seed for ALS VCO (~70MHz)
     * for now, we will use Keysight 33612A (Enomoto's own)
     * will be replaced to Keysight 33611A-OCX (ordered)

 * Common mode servo board [[KAGRA/Subgroups/MIF/AEL/CMSB|CMSB wiki]] [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8547|JGW-G1808547]] {*}
  * There was a request from AEL to finalize how many and what kind of variations we need
  * We currently have 5 and used for 1st MZI, IMC, CARM, PLL X, ALS PDHX
  * Needs 4 more? 2nd MZI, PLL Y, ALS PDHY, ALS COMM summing node

 * OMC status {*}
  * Calculations on DC power and circuit noise -> Somiya & Arai
   * Koji's calculation: [[KAGRA/Subgroups/IOO/OMC/DCPDCalculation|DCPDCalculation]]
  * Electronics status
   * In-vac DC PD amplifier board finalized [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9177|JGW-D1809177]]
   * In-air DC QPD amplifier board arrived (without chassis and interfaces)

 * ITMY inhomogeneity [[https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=8715|JGW-T1808715]]
  * We should check impact on sensitivity and locking as soon as possible
   * For both O3 and full bKAGRA
  * Somiya is working on FINESSE model to calculate higher order content of AS (AS RF before OMC and AS DC after OMC)
  * There was a discussion whether we should re-optimize OMC for BRSE or DRSE without homodyne angle optimization.

----

 * 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

 * 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)
   * It should be x2, x3, x6, x7, x8, x10, x16 (Michimura realized this on June 30) {*} {*}
  * 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

 * 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.