FPC Meeting on 2019/05/20 17:00 - (JST)

Participants: Kentaro Komori, Atsushi Nishizawa, Kentaro Somiya, SH Chunglee Kim, Kentaro Komori, Matteo Leonardi, Yuta Michimura, Atsushi Nishizawa, Kentaro Somiya, SH

Zoom meeting(2): https://zoom.us/j/6676627462

• Next meeting will be in early June before KIW ? (doodle poll will be circulated).

• Back to FPC page

Action items

• Update science scenario with new scoring while keeping the optimistic case for the funding request (Nishizawa)
• Update technology section and add another column like "additive" in the technology scoring sheet (Somiya)
  • DECIGO, Optical levitation, cooling capacity(?), ...
• Science Figure of Merits (FoM) for each scenario (Haino, Nishizawa, ...)
• New sensitivity curves (Haino, ...)

Minutes

• Any feedbacks from KAGRA collaboration since the last f2f ?
  • K.Yamamoto-san is checking the white paper
  • Related with Observing Scenario Paper (OSP) preparation, timelines towards O5 is in a discussion in LIGO. Currently, O5 will start in late 2024, while the duration of O4 is still in discussion (ranging between 1~2.5 years). So it is not clear how long we will have between O4 and O5.
• Science scenario (Nishizawa et al)
  • Scoring updated by considering detector network (A+, AdV+ and K or K+)
  • Scores for many science topics get worse as 0 (less than 20%), which is reasonable.

  • Improvement in the polarization measurements ? => If K+ sensitivity is not good the improvement is also limited

  • LF, BB and HF scenario
  • Primary and secondary science targets
  • Instead of choosing one or two (or dropping one) we should plan to achieve all the scenario but put priorities and time scale for each scenario
  • Based on technological scoring, FD-squeezing and HP laser are more feasible than heavy mass and/or suspension thermal noise improvement.
  • Following the technological feasibility study, we consider BB and HF as near-term scenario and include LF as middle-term scenario
• Science Figure of Merits
  • We want to evaluate each science scenario in the quantitative way.
  • Proposal: BBH(100?) range for LF, BNS(1.4?) range for BB and sky localization range* for HF

  • Sky localization range: average distance to achieve sky localization confidence area < X deg^2 (e.g. X= 20 ~ 16 @ GW170817)

• Additional scoring of technologies
  • Cost and risk in the scoring ? Are they already included in "Feasibility" ?
• New sensitivity designs
  • Production of new sapphire mirrors is the key to understand the baseline
  • Currently, we have no plan to produce new sapphire mirrors until O4, i.e. we will go without any spare ITM/ETM

  • A few weeks ago, Tomaru-san and SH visited iLM and discussed with Geppo and his group. As shown in KIW5, they submitted a proposal to procure a big oven in order to produce large sapphire bulk up to 200~250 kg and aiming low heat absorption (< 10ppm/cm).

  • If this is realized, sapphire can be a good candidate also for 3G competition with Silicon.
  • Since we benefit for both sides, PI and deputy-PI agreed to support their proposal and consider the collaboration.
  • As a FPC-related activities, SH is now researching a few companies for the polishing because it is one of the most costly and time consuming part. Based on the suggestion by deputy-PI, SH has briefly reported about this in today's chiefs meeting. Even though Matteo is currently the chief if MIR, it is a heavy duty for him to work both on sapphire mirror and squeezing/filter cavity. We should better share the work.
  • First let's define a big goal (dream) to use 200kg, 10ppm/cm absorption sapphire and see which sensitivity curves we can achieve. Heavy mass will help not only the radiation pressure noise bug also suspension thermal noise.
  • Can this dream plan go with 3G (ET and CE) to improve e.g. sky localization ?
  • Then for O5, we should consider at least two cases: optimistic and pessimistic, assuming, FD squeezing and HP laser are feasible in 5 years.
  • Optimistic case: we will produce new sapphire mirrors (even with 22kg) with ITM issued fixed and some tuning for the Finesse (like extreme RSE ?) and hopefully some improvement of heat absorption (20~50 ppm/cm ?)
  • Pessimistic case: we will not produce sapphire mirrors even for O5 and we have use the current one

  • We should limit the range of suspension fiber length (>30 cm ?)

  • For each cases (dream-3G, optimistic-O5, pessimistic-O5), we can evaluate the improvement with respect to 2G-O4 for three science scenario (LF, BB, HF)
• PAB report (Somiya)
  • There was a question about the general scheme that each group should obtain funding to do upgrades. Should it be better that young people decide what they do ?
  • Data analysis pipeline should be discussed in DAC white paper (or LVK white paper ?) instead of FPC white paper
  • We should invite experts in the system engineering or some of us should take a lecture like JAXA
  • What is the advantage of underground for HF option ? The sensitivity curve for LF looks not so good.
  • Issue on the ITM non uniformity.
• Mirror risk management
  • Currently, we don't have any spare for ITM nor ETM. If some accident happens to TM, KAGRA project can end at that point.
  • As a framework and motivation of FPC, SH is looking for some alternative companies for the polishing
  • Some company says that they can polish in nm-precision roughness but large curvature is not feasible.
  • Can we modify the IFO design to make an arm cavity even with flat TMs ? If so this could help us to reduce the TM procurement cost.
• Conferences

  • GWADW (Elba), May/19-25 - M.Leonardi, K.Yamamoto

  • KIW6, June/21-23 - A.Nishizawa(science review including O3,O4,O5) and S.Haino(FPC overview and white paper)

  • Amaldi conference (Valencia), July/7-12 - Y.Michimura, (and H.Shinkai for KAGRA status talk)