Ushiba, Fujii,

= ITMY =

• We started an investigation for the issue of ITMY (klog#9011).
  • We measured some BFY-excited transfer functions. It was found that:
    • in BFY2BFY-TF, the lowest peak at about 30mHz was not bserved, instead it was found at about 43mHz.
    • in BFY2BFY-TF, the DC-gain was smaller than the ther suspension (IX and EY) by one order of magnitude.
    • in BFY2MNoplev-TF, the payload main-chain mode at 0.34Hz was not observed, instead it was at 0.43 Hz.
  • It was also found that this newly-measured BFY2BFY transfer function was consistent with the one measured before the cooling-down work.
• For the next, will look for a sweet condition by moving the BF position.

Note

• Figure1, ITMY-TF.
• Figure2, ETMY-TF
• The order is:
  • (blue, light-green, brown, magenta, cyan, orange) = (BFY2BFY, BFY2MNYoplev, BFY2MNYps, BFY2IMYps, BFY2TMYoplev, BFY2BFY of IX).
• Figure3, ITMY-TF, measured on February 19th 2019. It seemed that the colling down started on Feb. 26th 2019.