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Participants: Participants: Matteo Leonardi, Tomotada Akutsu, Masayuki Nakano, Koji Arai, Ryutaro Takahashi, Osamu Miyakawa, Shinji Miyoki, Koji Nagano, Hiro Yamamoto, Kiwamu Izumi, Yuta Michimura
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 * DRFPMI trial was done when the alignment is not so good. With current alignment, DRFPMI might be possible [Masayuki]
 * We also need to consider if compound SRM is good or not. If not, we have to think about making a monolithic 0% SRM or 70% SRM (takes 0.5 years?). [Matteo]
  * Compound SRM was used for aLIGO O1 and O2, but KAGRA might have more issue with compound SRM since KAGRA have more HOMs at AS [Koji A.]
 * If ITM re-polishing is necessary to compensate TWE map, it takes 1 year with the most optimistic case to do them. [Matteo]
 * The effect of contrast defect and frequency/intensity noise coupling should be measured more directly. [Koji A.]
 * A/I for Michimura
  * Add these discussion to the document and send it to SEO
  * Draft: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11541
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 * We want to know what to do for O4 with birefringence and ITM transmission asymmetry
 * Summary of current measurements
  * X-arm round-trip loss from reflectivity is 86(3) ppm https://klog.icrr.u-tokyo.ac.jp/osl/?r=7307
  * Y-arm round-trip loss: NOT MEASURED YET		  * We want to know what to do for O4 with birefringence and ITM transmission asymmetry https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=11541
  * Cryogenic temperature?
  * SRM reflectivity: 0% or 70% or 85%
  * Polarizers in PRC and SRC?
  * ITM transmission asymmetry: re-coating necessary?
 * Summary of measurements so far
  * X-arm round-trip loss from reflectivity is 86(3) ppm (if we assume no birefringence) https://klog.icrr.u-tokyo.ac.jp/osl/?r=7307
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  * Power recycling gain for the sidebands are
  * DRMI on 1f is fine. Lasts 30 min or so		   * Power recycling gain for the sidebands are 2 or so (very rough estimate).
  * DRMI on 1f is fine. Lasts 30 min or so.
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  * CMRR for intensity noise. https://klog.icrr.u-tokyo.ac.jp/osl/?r=13028

 * Summary of calculations
  * Effect of ITM asymmtery to sensitivity: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=10352
  * Effect of ITM asymmetry to ASC: https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=10359
  * Effect of inhomogeneity (without birefringence): https://journals.aps.org/prd/abstract/10.1103/PhysRevD.100.082005
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  * Try DRFPMI locking for one more week.
  * Updated shot noise calculation https://klog.icrr.u-tokyo.ac.jp/osl/?r=12772
  * X-arm and Y-arm reflectivity/loss measurements with polarization considered
  * Re-measurement of CMRR for frequency noise https://klog.icrr.u-tokyo.ac.jp/osl/?r=13069
  * Measure power recycling gain for sidebands (POP 2f with FPMI locked and PRFPMI locked)
  * Measure MICH contrast defect with MICH locked and FPMI locked
  * OMC cavity scan to scan mode content of AS beam
  * Measure if there are any structure to DARM sensitivity coming from compound SRM.
  * Scattered light measurement in PRC by sweeping PRM and PR2/3 deferentially.
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  * DRFPMI LSC and ASC sensing matrix with birefringence and ITM transmission asymmetry
  * Frequency noise and intensity noise coupling with birefringence and ITM transmission asymmetry
  * MICH/PRCL/SRCL to DARM coupling with birefringence and ITM transmission asymmetry

 * O4 Schedule https://gwdoc.icrr.u-tokyo.ac.jp/cgi-bin/private/DocDB/ShowDocument?docid=9209
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  *   * We are not sure yet whether birefringence is limiting our sensitivity and stability. DRFPMI locking probably possible with current interferometer.
  * Putting polarizers inside PRC and SRC might improve the sensitivity and stability, but it might introduce some extra issue (thermal lens, extra loss, scattered light etc).
  * May be better to focus on characterization of the interferometer and the preparation of better ITMs rather than the preparation of polarizers.
  * It is always good to prepare for the unexpected if we have manpower and money. Preparing polarizers now might save our lives in the future.
  * Measurement listed above must be performed before the vent for O4 to characterize the current situation and to make a plan for O4.

ISC Meeting on 2020/03/09 14:00 - 15:00

Participants: Matteo Leonardi, Tomotada Akutsu, Masayuki Nakano, Koji Arai, Ryutaro Takahashi, Osamu Miyakawa, Shinji Miyoki, Koji Nagano, Hiro Yamamoto, Kiwamu Izumi, Yuta Michimura

Zoom meeting: https://zoom.us/j/6676627462

Next meeting

TBD

back to Meetings page

Minutes

  • DRFPMI trial was done when the alignment is not so good. With current alignment, DRFPMI might be possible [Masayuki]
  • We also need to consider if compound SRM is good or not. If not, we have to think about making a monolithic 0% SRM or 70% SRM (takes 0.5 years?). [Matteo]
    • Compound SRM was used for aLIGO O1 and O2, but KAGRA might have more issue with compound SRM since KAGRA have more HOMs at AS [Koji A.]
  • If ITM re-polishing is necessary to compensate TWE map, it takes 1 year with the most optimistic case to do them. [Matteo]
  • The effect of contrast defect and frequency/intensity noise coupling should be measured more directly. [Koji A.]
  • A/I for Michimura

Agenda

KAGRA/subgroup/ifo/MIF/Minutes20200309 (last edited 2020-04-17 23:38:36 by YutaMichimura)