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VIS (SRM)
mark.barton - 20:12 Wednesday 28 November 2018 (7175) Print this report
SRM Installation

With Hirata-san and Fabian.

Today:

  • Fabian estimated the excess length in the cables around the BF and SF, in case we ever do this again and want to optimize the cable lengths. See paper logbook (or Google Photos).
  • We took position-count data for calibration of the F0 LVDT sensing. See forthcoming separate klog.
  • We noted the F0 LVDT actuation sign was reversed, but didn't have time to correct it.
  • We put 6 x 38 mm x 120° (CAD amount) + 4 x 19 mm x 120° arc weights and the geophones on the IP.
  • We adjusted the security structure to be vertical and centered around the hanging chain. (We used the manual F0 yaw adjuster to correct some yaw of the chain and then loosened the top poles of the SS to set the angle to the vertical and the gaps around the hanging chain.)
  • We unlocked the IP and adjusted it to be approximately central and without yaw.
  • We locked the IP, and rechecked the security structure and it was still good.
  • We set the F0 fishing rod to mid-range.
  • We unlocked the BF and SF keystones and checked that they were close to nominal height.
  • We put a small amount of extra mass on the F0 keystone to get 11. 5 mm keystone height.
  • We left the IP locked, but everything else unlocked and ready for TFs.

Things remaining to be done before craning:

  • TFs of F0 and everything below.
  • Inventory of the weights that were used on the SF.
  • Check the pitch of the optic with the OL and adjust if necessary.
  • Further the centering and yaw of the IP and check the actuation signs.
  • Set the SF damper to 6.5 mm.
Comments to this report:
fabian.arellano - 10:28 Thursday 29 November 2018 (7182) Print this report

I attach an spreadsheet with the calibration data of F0 LDVT. The following applies:

  1. Nominal position: 11.5 mm.
  2. Calibration factor: 0.147 µm/count.
  3. Offset to set in the medm screen: +585 counts.
  4. Linear range: 4 mm total, [ -2.5 , 1.5 ] mm from the nominal position.
  5. The slope of the line shown in the plot is negative because the position reference is above the keystone and the gap increases as the keystone goes down (see picture in the spreadsheet). Nevertheless, the calibration factor is written as positive in the medm screen.
  6. The medm screen as been modified already.
Non-image files attached to this comment
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