FPC Meeting on 2019/05/20 17:00 - (JST)
Participants: Kentaro Komori, 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).
- 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, icing of TM, cooling capacity(?), ...
- Science Figure of Merits (FoM) for each scenario (Haino, Nishizawa, ...)
- New sensitivity curves (Haino, ...)
- 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 or K+ (4th detector) 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. (e.g. arxiv:1902.09485 thanks to Somiya-san)
- 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" ?
- Let's add "additive" in the scoring
- 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 of 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 but also suspension thermal noise.
- Can this "dream" plan go with 3G (ET and CE) to improve e.g. sky localization, or anything else ?
- 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 issues fixed and some possible tunings 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 to 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 the funding to do upgrades. Should it be better that young people decide what to 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 (SE) or some of us should take a SE lecture like JAXA does.
- What is the advantage of underground for HF option ? The sensitivity curve for LF looks not so good.
- Issues 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.