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• Minutes20180409

ISC Meeting on 2018/4/9 14:00 - 15:00

Participants: Osamu Miyakawa, Yoichi Aso, Yutaro Enomoto, Keiko Kokeyama, Koji Arai, Hiroaki Yamamoto, Tomotada Akutsu, Kentaro Somiya, Yuta Michimura

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

Next meeting

2018/4/23 (Mon) 14:00 - 15:00 ?? (upto Phase 1 operation status)

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Minutes

• KAGRA configuration for joining O3 [Michimura] JGW-T1808126

  • Maybe we should check if continuous alignment to OMMTs is necessary or not. Alignment to OFI could be done only with OMMTs. [Somiya]
  • OMC commissioning will start soon, and we will experimentally check which is better, RF readout or DC readout. [Somiya]
    • Comparison between RF readout and DC readout should be done with calculations also
  • Difficulty of locking RSE and PRFPMI is almost the same if we have ALS in our hand. The hardest part is handing off CARM from green to IR. [Arai]
  • f1 buildup is x10 less without SRC. This will be critical for MICH, and ASC of differential arm. Achieving both lock and good sensitivity is almost impossible with PRFPMI. [Aso]
  • Simpler configuration gives more time for noise hunting. PRFPMI is more simple than RSE and should be easier. [Miyakawa]
  • I heard that joining O3 is very important for KAGRA since we have a MEXT review by 2021. [Kokeyama]
  • Is is so critical for KAGRA to join O3? Why not O4? [Arai, Hiro]
    • In high event rate regime expected in O3, KAGRA joining O3 could be minimal from the scientific point of view.
    • It will be a better strategy to build a fully functional KAGRA targeting to join O4.
    • I am not optimistic if LIGO is willing to extend the end of O3 for KAGRA. [Hiro]
      • Anyway, Kajita-san already announced LV to join O3 and we have no other choice right now.
    • If the chance is to join O3, the important factor will be if KAGRA can show that it will be surely operational in time, not promising descent sensitivity.
  • I wanted to talk more on technical things, not political things... [Akutsu]
  • Conclusion
    • Most of attendees were positive for RSE.
• 2inch SRM status [Hirose via email]
  • 2inch SRM will arrive this Month
  • We need a review how to fix this optic to the doughnut metal mass.

Agenda

• Site report

• KAGRA configuration for joining O3 [Michimura] JGW-T1808126

  • There is a discussion to go with PRFPMI for O3.
  • SRM doughnut metal mass status? black coating?

• bKAGRA RF cables [Michimura] klog #4362

  • purchased almost all the SMA cables, except for 30m cables

• RF generation using Mach-Zehnder interferometer [Kohei Yamamoto] JGW-G1707309 JGW-G1807655 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 (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: 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? (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 JGW-E1707416 JGW-T1200788 ALS Wiki

  • where to put a frequency offset: arm length or PLL offset [Enomoto] JGW-L1807726

  • fiber selection meeting on March 23

    • determined to use end-cap for both
    • there was a suggestion to lay IR fibers also
• 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 JGW-D1808028

      • if Wenzel reference is input, it gives -155 dBc/Hz @ 100Hz for f1, -147 dBc/Hz @ 100 Hz for f2

      • meets the BRSE requirement (but not DRSE requirement without f1 AM) JGW-T1200913

      • updated specsheet (with updated phase noise and harmonics requirement) and quote arrived
      • will order at least two units

      • 14 weeks of delivery, order soon !!

  • Usage of 6 Agilent N5181B 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 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 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 this page for other agendas.