= ISC Meeting on 2015/11/30 =
14:00 - 15:15 on SeeVogh

Participants: H. Yamamoto, Michimura, Aso, Akutsu, Okutomi, Hirose, Somiya


 1. Requests for coating requirements from LMA (Aso)
  * We got requests to relax requirments for coating of various mirrors from LMA.
  * The following changes will be made
   1. Green transmission for TMs
     * Finesse of the arm for green should be higher than 6 to avoid unwanted resonances of higher order modes. For safety, we decided to make it 50. With the relaxed transmission error, the finesse will be in the range of 40 - 60, which is still fine.
     * Old: 6% +/- 0.5%
     * New: 6% +/- 1%
   1. ITM AR reflectivity
     * ITM AR reflection will be used as POX and POY. Therefore, we need non-zero reflectivity. The PRC cavity can tolerate a loss of 1000ppm.
     * Old: 200ppm +100/-0
     * New: 300ppm +/-100ppm
   1. ETM AR reflectivity
     * The ghost beam from the ETM AR will be separated inside the BRT when the beam size becomes small. 
     * Old: <50ppm
     * New: < 100ppm
     * Reference: LIGO requirement is < 500ppm. Actually measured value vary a lot from 20ppm to 700ppm.
     * The difference between 50ppm and 100ppm is insignificant
   1. PRM/SRM AR reflectivity
     * Separation of the PRM ghost beam was not yet considered.
     * Old: < 50ppm
     * New: < 100ppm
   1. SRM HR transmission
     * Old: 15.36% +/-0.1%
     * New: 15%+/-1%
     * The linear range of the SRCL signal is fine with this relaxed error range.
     * The WFS shot noise change only about 5% with the above error.
     * Somiya-san will check the effect on the sensitivity.
 

 1. Electronics Preparation Status (Michimura, Aso)
  * Cable (Michimura)
   * Delivered to the site. Now in the tunnel (低温機械室)
   * RF flexible cables are also included, but some RF flexible cables are in NAOJ room at Kamioka.
   * See [[https://docs.google.com/spreadsheets/d/1VPkv64gDrbhSX4LiO5aNc-miSf3h3pl1dRQPKUhnuCs/|this ISC cable list]].

  * RF distribution (Komori, Michimura)
   * The panel should have been delivered to Kamioka
   * Need to arrange people to assemble the box

  * RFPD/QPD (Aso, Doi)
   * The first delivery will be in the middle of Dec.
   * For MC lock, we need one extra RFPD. We have the stuffed PCB but no box. Fujisawa-san at Toyama University is now making a box. Asked Doi-san to supervise her and finish the box production by the end of the week of 11/30.

  * Diff-to-Single converter
   * For bKAGRA, we need to make official converters.
   * For iKAGRA, we can use a passive conversion boxes. Just connect the cold line to GND through a resistor (1kOhm or so).
   * The above box needs to be made

 1. Magnet Noise (Michimura)
  * Decided to reduce the size of BS magnets by a factor of 30 from the current design. IM magnets will also be smaller (1/3 to 1/10).
  * VIS members (Mark and Fabian) will design new flags for the BS and SR

 1. OMC (Somiya)
  * We need to decide where to level the beam in the output chain: Befoer OFI ?, after OFI ?
  * Do we need steering mirrors before OFI ? -> Needs to be discussed with quantitative assesment of scattering noise from various optical components.
  * How much light power will be picked off for the AS WFS ? -> 1%
  
 1. FFT Simulation (Hirose, H. Yamamoto)
  * No update