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Reports until 17:12, Wednesday 20 September 2017
H1 AOS
betsy.weaver@LIGO.ORG - posted 17:12, Wednesday 20 September 2017 - last comment - 16:29, Monday 21 August 2023(38727)
Today's in-chamber vent report

Vent progress today:

HAM2 (Hugh, Kissel, Jim, Rick, Sheila)

HAM2 ISI dampers are installed, minus the 3 TMDs which are currently being tuned by Jeff K and will be reinstalled in ~ the morning.  Thanks to Sheila The Bolt Breaker for crumpling and contorting her skeleton in order to reach those difficult to reach ISI guts in that one corner inside the ISI.

Rick assisted with unplugging and moving the ISS array out of the way for the damper install.  He also hunted more appropriate cable relief hardware which he'd like to install in the next few days when the ISS goes back into place.

BSC3 (Betsy, Travis)

ITMX was thoroughly inspected to check for any mechanics* which may have cause the IFO to need it to be maxed in pitch after the May cleaning vent.  All looked fine with zero pitch offset and with maxed pitch offset.  We have zeroed the biases on the main and reaction chains and will reset both chain mechanical pointing to the optical lever when we reinstall the new ITM optic. 

While looking at it, we also mapped the optical lever beams heading out of the viewport down the manifold (Travis hoofed it down there with a head lamp, target and a pen while I steered the suspension around with a CDS laptop).  I'll post results of that separately - at first glance the CP-HR beam and ITM-AR beam look much closer together than we found months ago on the ITMy, good.

Started work to remove the sleeve, vibration absorber blocks, wedges, structure cross braces, and flooring panels (to get the sleeve off).  Face shields were added to the exposed QUAD optic surfaces.  (The suspension is still suspended so violin measurements can be done in the next day or so after we get the LSAT on the structure for measurement equipment support.)

HAM3

Bubba, Mark, and Tyler removed the doors from HAM3 today.

Jim locked the HAM3 ISI.

 

* All 4 main chain pitch adjuster rods were found tightly locked in place.  All chain cabling was as we left it - nominal, not touching any place it shouldn't.  The ACB assembly was still nominal at only ~1mm away from the QUAD structure, but not touching. All magnet flags looked reasonably centered at all stages.  All EQ stops looked well positioned and not touching.  Nothing was found that possibly fell from higher up and landed on a stage in order to cause a pitch change.  (Recall the suspension had a clean bill of health via TFs a few times over the last month, so we didn't expect to find anything really.)

 

Comments related to this report
jeffrey.kissel@LIGO.ORG - 18:15, Thursday 21 September 2017 (38739)DetChar, SEI
Link 

J. Kissel

I second the many thanks to Sheila for getting in all of the damping mechanisms for the "Corner 1" blade and V2 GS13 can. I attach some great pictures of her crumpling skills. 

Also attached are pictures of the blade tip and flexure dampers post-install. While the flexure dampers arrangement isn't amazing, I'm quite confident viton is forgiving enough that this will still do the job. I'm also confident that although it looks messy, the flexure damper still won't move around.

Note because this was a difficult ask to just install these components, I made the executive decision *not* to B&K hammer the blades as we'd done for Corner 2 and 3 (in LHO aLOG 38716). The cabling would likely have been a nightmare to keep from touching the innards of the chamber, let alone trying to get a good strike with the hammer while not interfering with the table / measurement. We've seen enough post-blade-tip-damper-install blade responses to know that the fundamental blade mode moves from 153 Hz to 139 Hz, and the Q of the TMDs is low enough that it'll cover any spread we see. (However, this is an exception, we will continue to hammer ever other HAM blade.)

And for the record, at the close of business this day, all of ISIHAM2's dampers (save the to-be-tuned TMDs) on all corners have been installed:
    - Blade-Tip Dampers
    - Flexure Dampers
    - Horz. and Vert. GS13 Can Dampers

Also, also, I grabbed a publicity photo of the back of MC3 while I was there.
Images attached to this comment
jeffrey.kissel@LIGO.ORG - 16:29, Monday 21 August 2023 (72361)EPO
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Retroactively tagging EPO for the great pictures, now that we have the tag!
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