ISC Meeting on 2018/8/27 14:00 - 15:00

Participants:

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

Next meeting

2018/9/10 (Mon) 14:00-15:00 (JST)

https://www.timeanddate.com/worldclock/meetingtime.html?day=10&month=9&year=2018&p1=248&p2=4399&p3=137&iv=0

back to Meetings page

Minutes

Agenda

• Main topics for Phase-2 [Michimura]

  • Fix initial alignment scheme for full IFO
    • Enomoto?

    • For XY arm 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

    • Michimura's trial JGW-D1808336

    • Izumi started from ALS cabling diagram and then FSS cabling JGW-D1808394

    • Making a whole cabling diagram would be tough, but cabling for RF PD/QPDs is kind of obvious and we can simplify them.
  • In-vacuum RF PD and RF QPD
    • Izumi will ask LIGO people first. And ask Doi for handling fabrication?
  • Readout DC PDs and OMC
    • DC PDs purchased. We have to make holders and in-vac amp. Somiya?
  • Design output optics on optical tables
    • REFL [??]
    • POP [done for green; ? for IR]
    • POS [done for green; ? for IR]
    • TRX/TRY [K. Nagano for both IR and green]
    • AS [??]

• RF modulation system

  • Agreed to work on both three-f and f3 for redundancy

    • Harmonics generator modified for three-f, modification ordered on Aug 3, shipping by Oct
    • Broadband PD for three-f?
  • MZI experiment

    • There was a proposal from MZI team to keep MZI (including delayline) for O3

      • Do we all agree on this?
    • Status

      • Both MZIs locked, noise requirement not yet met, modulation depth measured but not quite right JGW-G1808871

• Low noise VCO

  • LIGO one (79-81 MHz) LIGO-D0900605, spec LIGO-E1101019

    • needs 71 MHz reference source
  • at least 5?
    • FSS AOM (80 MHz), ALSX AOM (80 MHz), ALSY AOM (80 MHz), PLLX (40 MHz), PLLY (40 MHz)
      • 80 MHz for PLL possible? PFD spec?

    • draft of circuit production request JGW-T1808339

    • VCO modification LHO alog #30869, LIGO-E1600292

  • G&H VCO for ALS AOM turned out to be too noisy

  • Make low noise VCO similar to aLIGO one JGW-G1808433

  • RF power seems to be enough to drive ALS AOM
  • Replacing Refcav AOM (currently at 110MHz) will be after ALS AOM

• ALS configuration JGW-E1707416 JGW-T1200788 ALS Wiki

  • ALS schematic diagram on ALS Wiki updated to reflect recent changes

    • summing node for ALS COMM (fast servo is necessary)
    • use feedback signal instead of error signal for ALS COMM
    • use SLOW instead of FAST for ALS VCO loop (DC gain necessary)

  • possibility of using PLL VCO for locking green PDH?

  • 50m green fiber laid
  • RF PD for green
    • Decided not to use commercial ones for green RF PDs. Modify our IR RF PD to green.

  • ALS circuit diagram JGW-D1808394

• How to proceed with DC PDs for DC readout [Aso]

  • Calculations on DC power and circuit noise -> Somiya & Arai

    • Koji's calculation: DCPDCalculation

  • Box for in-vac amplifier
    • VIC?
    • How to extract heat? Alumina coating? Fix on the optical table (be careful of electrical short)?

• 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
• 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

      • 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 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.