== LVC meeting (parallel session) ==
 * SH could join the LVC meeting only in the first two days (parallel sessions) mainly in AIC and joint instrument plenary
 * [[https://dcc.ligo.org/cgi-bin/private/DocDB/DisplayMeeting?conferenceid=1022|DCC link to the agenda]] (Many of them are not KAGRA-readable)

== Some topics picked up by SH ==
 * [[https://dcc.ligo.org/LIGO-G1900521|kHz optimization for BNS post-merger (Haixing Miao)]]
   * Long SRC to dig into high frequency (kHz) region. Sensitivity will be limited by SRC loss.
   * Typically 6km arm with 150m SRC to make some detection of post-merger (~1 event/year)
   * 18 km arm may be needed to do some astronomy (~10 events/year)
 * [[https://dcc.ligo.org/LIGO-G1900515|Finesse 3]]
   * python implementation
   * It enables custom detectors (e.g. homodyne detector)
   * It can take account of 3G detectors (e.g. polarizing beam for Sagnac)
 * [[https://dcc.ligo.org/LIGO-G1900404|Low loss Faraday Isolator for squeezing injection]]
   * Try to reduce the optical loss which is limiting the squeezing level (currently ~3dB at LIGO)
   * Matteo's contribution mentioned
 * [[https://dcc.ligo.org/LIGO-G1900585|High power laser for O4 and 3G]]
   * Original High Power Oscillator (HPO) was given up due to the maintenance issue and the beam jitter affecting the sensitivity
   * Two neoVAN-4S-HP (solid state) amplifiers (+70W each) in series following LIGO front-end laser (30W) or NPRO seed (2W) to get 140~170 W power for O4
   * Development of fiber amplifiers at LZH in progress. To be tested at AEI Hannover soon.
   * Coherent beam combining (CBC) with two neoVAN-4S-HP amplifiers and/or fiber amplifiers can be tested at AEI Hannover.
   * Benno's AEI Hannover group is always supportive to KAGRA
 * [[http://www.gravity.uwa.edu.au|Gingin facility at UWA]] (DCC link is not KAGRA-readable)
   * Study on Parametric Instability - possible collaboration for KAGRA+ ?
   * 5W 2micron laser for silicon mass cavity
 * [[https://dcc.ligo.org/LIGO-G1900564|AdV suspension control status]]
   * Sensitivity improved from 25 Mpc to 40 Mpc by mitigating actuation electronics common mode noise coupled with electro-static charges
   * Electro static charge issue is important even for coil magnet actuator for Virgo (and KAGRA) and not only for ESD in LIGO
   * Still unknown noise around 100 Hz which avoids achieving stable sensitivity of 60 Mpc for Virgo (possibly still actuation noise ?)
 * LLO commissioning (DCC link is not KAGRA-readable)
   * Noise projection to O3; ER14 120-140 Mpc
   * Stable operation with 40W laser power but more noise with 50W
   * 3dB IFO measured squeezing achieved
   * Reduced ESD noise and stray field monitoring
   * Non-uniform absorption at TM optics - serious problem avoided for now by moving the beam position
   * Musical VCOs => for more robustness
   * Should be no big surprise for O3
 * Squeezing at MIT (DCC link is not KAGRA-readable)
   * Why not more than 3 dB ? => Angle noise, Losses, Pump power and Radiation pressure (in principle) 
   * Loss inside IFO: 30% expected but in reality 4~50 %
   * Towards O4: more than 3dB, A+ goal: 6dB (measured squeezing level)
 * [[ https://dcc.ligo.org/LIGO-G1900594|Voyager update]]
   * Silicon Suspension design and noise estimation updated by K.Arai
   * Is it really good to use the ribbon suspension ? (SH's personal thoughts and also discussion with Helios)
   * Tuning of quantum noise to be considered ; one possibility like high frequency tuning (related to Haixing's talk)
 * Coordination of prototypes (S.Hild)
   * Global coordination of prototype facilities is needed and also to be discussed among (LSC, Virgo, KAGRA, GWIC, ...) (David Shoemaker)
   * After the GW detection we are more restricted to keep observation for science (Ray Weiss)
   * If we have 4~5 detector in the world (including KAGRA and LIGO-india) we can rotate the down time for the upgrades ?
   * Still not clear conclusion in this meeting how to coordinate and define the roles of each prototype facilities
 * [[https://dcc.ligo.org/LIGO-G1900203|Point absorvers at aLIGO]]
   * Looks like to be getting one of the major issues
   * 4 out of 8 TM optics at LHO and LLO show some indication of point absorption
 * [[https://dcc.ligo.org/LIGO-G1900503|KAGRA+]] (5~6 comments/questions were given)
   * (David) what is the time scale ? => Something like O5 and beyond
   * High power (HF) option is to give up the cryogenics ? => No we keep basically around 20 K by thicker and/or shorter fiber suspension
   * Suspension with different material with higher Young's modulus ? => We should consider about that
   * Long filter cavity possible ? => in principle yes but the space inside the tunnel is limited; 30m is Ok >30m needs some efforts
   * EPR entanglement should need shorter filter cavity => we should consider some QND for the far future options