Minute of KAGRA commissioning meeting
- Date: 2018/7/17 11AM~12PM
- Attendance: Miyakawa, Miyamoto, Aso, Nakano, Yokozawa
- eZuce: Shoda, Izumi, Ushiba
Clipping loss (Izumi)
- 20mm misalignment is acceptable for beam cetering.
- 40mm misalignment is acceptable for WAB cetering.
- Could be factor of 2 different in loss.
ETMX (Miyamoto)
- Side of screw of frame was almost touching in the room temperature and after starting cooling it was actually touching.
- Then it was found that F2 was almost dead. Even VIS team pulled wire but LVDT did not work.
- Then pump down started without F2 fix.
- New measurement shows it seems to be OK except for 2.4Hz peak probably due to the dead of F2.
- Cooling started the last Friday.
- Heat link does not affect so much.
LAS
- Fiber was broken just before moving the laser to Kamioka.
- We have 1 + 1spare = 2.
- Low power below 15A has many peaks.
- Low frequency RIN is proportional to the power.
40W laser and RIN measurement -> Tahara, Nakano
- Noise floor increase with power increment.
- Movement to Kamioka will be the end of July.
ALS
VCO noise measurement -> Sugimoto, Enomoto
- Any good idea to control only high frequency? (Aso)
- 40MHz less noise VCO can be used for also high frequency.
Green Fiber Noise Measurement -> Sugimoto, Enomoto
- Transmissivity was 60% first, then reduced to 40%.
- 5m fiber noise was measured and fitted, and will be scaled to 50m longer.
VIS
Geophone Noise Hunting -> Tanioka
- Circuit inside of pre-ampifier seems to be something wrong.
- LED light can be a noise. (Miyoki)
- Long cable could be noise, but after changing did not fix.
- Current monitor of HPCD can oscillate easily. At the coil output, no noise increment, no strange transfer function can be seen, but we did not check offset jump. We should do.
AOS
WAB alignment and the final saving-mode -> Akutsu, Simon
rack cleaning
- Cable cleaning on BS rack will be done this weekend.
- pile of AA or HPCD can be hot.
Others
Necessary number of High power coil driver -> Aso -> Current number of HPCD including 16 spares seems to be enough.
NAB PD cabling -> Aso
- Beam height brain storming
- ETMX and ITMX should be located at half low temperature stage and room temperature stage. It means that ~5mm off from the nominal position. Type A can compensate ~5mm.
Where is an actual beam hight? -> 30urad * ~10m -> not a big amount.
- Effect of window of gate valve?
Others
- Next meeting: 7/17.