Minute of KAGRA commissioning meeting

Date: 2018/7/24 11AM~12PM
Attendance: Miyakawa, Aso, Enomoto, Yokozawa, Kozakai
- eZuce: Miyoki, Suzuki, Nakano, Shoda, Ushiba, Yamamoto, Kimura, Uchiyama

LAS (Nakano)

40W laser started working on last Friday.
- Limite 1W will be used to alignment or so.
Remote desktop will be installed on Windows PC for 40W laser control.
Monitor of laser power should be displayed on door or something.

MZ of single arm mode matching is much better now. No Lager-Gaussian is seen.
- MZ contrast is 99.4% and 96.9%. Second one has 3m arm length difference.
- Lock wil be tried soon. Common mode servo will be used to control MZ.
RAM(residual amplitude monitor) monitor will be installed.
ISS TF model and measurement were done. Model still does not have phase delay at high frequency.
RIN is limited by PD dark noise up to 1kHz. Shotnoise is almost comparable.
- UGF is currently 10kHz. Above 1kHz, suppression is not enough. It will be limited to 50kHz max in future by AOM driver.

MZ alignment is being proceeded, and MC has been already locked with single arm of MZ.

On 7/9, we started take IMMT out from the chamber.
All the replacement of magnetized screws is done by the end of last week.
Mirror position (distance between mirror and coile) was shifted a ~mm, probably caused by tilt of optical.
TF will be measured soon.

To fix BS GeoPhone, we should open the chamber.
TMS GeoPhone looks fine, but some strange coupling can be seen in the TF measurement.
- Feedback bandwidth is limited ~10Hz.

DAC is almost out of stock. We should think to start using old DAC used in CLIO.