CARM signal detection by using 2nd PD 2023/07/24

Participants: Komori, Aso, Miyoki, Ushiba, Uchiyama, Miyakawa, Akutsu, Dan, Oshino, Washimi, YamaT, Takahashi.R, Kanda,

Zoom meeting: https://zoom.us/j/5045179604

Minutes

• Presentation by Komori-kun

  • 2/7 CARM out of loop measurement.

    • Old estimation: shotnoise should be below the unknown noise (< kHz).

    • For noise budget: If shot noise at in-loop PD1 limits, the shot noise of PD2 has no coherence with shot noise at PD1.
    • Analog excitation is necessary for injection. But MOC is connected at this point. So we need cable reconnection. SW can be introduced?
  • 3/7 RF PD
    • We have several.
    • Shunt R should be removed. Tune RF properties.
  • 5/7 Reck preparation: OK
  • 6/7 Where we should put PD2?: Wide space
  • 7/7 Schedule: Aug/21~28 (2 days)
• Opinion:
  • How about 3rd PD for the MICH control?
    • CARM PD can be used, however, the laser power is minimized for CARM. While MICH requires more power!

    • Haoyu calculated we could obtain a better S/N signal or not -> Yes!! 10 times better than CARM Q phase signal.

    • 2nd PD can be used for this purpose?
    • 50mW can be detected by these PDs.
    • 10W is necessary.
    • Model number will increase. Can we?? Dual IQ can be added in a rack?. Quad IQ can be used for minimization? Whitening one more.
    • Let's put 3rd PD anyway. After we will check DGS.
  • The 2nd PD will not require Dolphine?