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|* []||* [[http://klog.icrr.u-tokyo.ac.jp/osl/?r=5255]]|
Workers: Akutsu, Ikenoue, Simon, L. Shimizu, Yokozawa
Hanged up the whole NAB tower (the NAB suspension + the inner tower) with the ceiling crane.
- Again laid the wooden (but covered by white tapes) bar to keep the distance of the two slings at the hanging points; this time the bar was softly taped to the inner tower's upper beam in order to avoid accidental fall off to the NAB.
Found the vertical move of the crane by one click was also ungentle.
Again used two (but new) koyoris to control or handle the NAB tower to avoid the accidental rotations (pitching, yawing, and rolling); the koyoris were handled by two workers.
Note: one crane person (Ikenoue) , two handlers (Simon and Shimizu), one watcher (Akutsu); so this work needs 4 people at least, hopefully 5 people (Yokozawa)!
- Transported on the IXA chamber.
- Handled by koyori as well.
- To find where is the center, firstly I stepped on the chamber and looked down at the center with my eyeballs.
- Hanged down the NAB tower into the IXA chamber while looking carefully whether the inner tower's four feet, which were the most sticking out, would not crash the chamber.
- Tried to sit down the NAB tower on the optical table in the chamber, but the one vertical step of the crane was so coarse (as described above) that it bounced on the table and made large sound!
- Hanged up the NAB tower again, slightly.
- I (Akutsu) entered into the chamber from the top, as the side doors were barriered by the inner tower's pillars; note that the NAB tower was hanged around the center of the chamber at this timing. First I tried to use a long ladder, which Uchiyama-san prepared, but we could not set the ladder stably in the chamber. So, we put a short ladder-like step, and I stepped down into the chamber with it from the top of the chamber.
- Then I put a laser leveler, and shot a vertical line so that the laser line was along a red line drawn on the optical table; the red line was drawn as a projection of the actual (but assumed) interferometer's laser line by Yokozawa-san, Uchiyama-san, and Telada-san the other day.
- Tried to set guide blocks along the feet of the NAB tower, when it was in the nice alignment and position. But we don't have nice ways today; today we used dog clamps, which were used to fix the inner tower's feet before, as the guide blocks, but we could not find how to fix them... anyway we used white tapes to fix them, but the tapes were too weak against the dancing NAB tower.
- Shifted about 10cm in +X direction
- Pushed the NAB tower in +X direction about 10cm so that TCam's requirement can be fulfilled.
- With pushing it, lowered the NAB tower by the crane; large sound again, but it sat on the optical table somehow.
Workers: Akutsu, Ikenoue, Simon, L. Shimizu
- Aligned the NAB tower further
- Inserted a clean lever block between the crane's hook and the slings; the lever block was borrowed from VIS (and got back later). We actually liked to use a chain block, but the max weight of the VIS's clean chain block was 250kg, which was comparable to the weight of the NAB tower, so we avoided the chain block. As the hook of the lever block was relatively small, we used two shackles to connect the hook and the slings.
- After several trials, the NAB tower was sat on the optical table.
- Some shims were inserted underneath the feet of the NAB tower.
- Fixed the NAB tower
- Used two dog clamps for each foot of the NAB tower.
- Tighten the dog clamps symmetrically by two persons.
- Note: due to the bad design of the dog clamp, we cannot find any nice screw holes for regular usage of the dog clamps... Need new design!
- Released and balanced the NAB
Before stating, set up the laser lever to shot cross laser beams; the vertical one was aligned to the red line drawn on the optical table, while the horizontal laser line was aligned by my eyeballs, at first. Interestingly, the laser light beams were matching all with the drawn lines on the optical table and the inner tower, so I think the inner tower got back to the original position almost.
Release the EQ stops for the NAB from the top; the reason why we started from the top is to reduce forces to the suspension wires.
- Fortunately, without any precise alignment the suspended NAB seemed balanced; balancing work sufficiently in Mitaka would be helpful!!
- It seemed the laser lever showed the NAB was centered (note that there is uncertainty due to the eyeball fitting.); According to eyeballs, the NAB was slightly rolled, but I think this is within allowable level.
- Installed a viewport window for oplev
- ICF70, S/N001 for oplev window.
- This will be used to test the frequencies of the NAB.
- Chain block for 500kg. (What I found was that of 250kg, which Hirata-san had, and the NAB suspension +the inner tower would be comparable to this number so I felt it was dangerous to use the one.)
Guide blocks to guide the inner tower + NAB suspension. They are must!!
Modified dog clamps to clamp the legs of the inner tower. They are must!!
- A small bottle for ethanol
- Long ruler; use with a laser lever
- We found installing the dampers is mostly impossible the current structure; !!!! Urgently discuss how to resolve this!!!!
- The crane should be renewed!
- Measure the resonant frequencies and damping factors.