Akutsu, Yano, Tanaka, Simon
After the delivery of the NAB into the IYA clean-booth, we firstly checked the balance of the baffle while it was still inside the construction-jig in order to observe any misbalancing happen due to the transport before we proceed with inserting into the chamber:
- Firstly, we balanced the jig with its feet
- Then, we released the baffle and checked the situation with a bubble-level and a laser-level
- Pitch seemed quite well balanced and we did not see any misalignments in logitudinal, transversal, or vertical direction (at least not with our eyes)
- We found a slight roll-misbalance but this seemed to be there from the beginning
After this first check-up, we fixed the baffle again.
Take-out the NAB
We moved the jig under the crane and screwed the eye-bolts from the jig on the NAB-structure (on the bottom yaw-adjuster plate). Then, we used two slings for clean-booth use (thanks to Hirata-san who gave them to us) and connected them to the eye-bolts with some shackles. Another shackle was connecting the slings to the crane's hook.
Note: We are using a chain block in addition to the (very rough) crane in IYA for realizing a smooth lift.
In order to take out the NAB from the jig, we had to remove the M5 screws which are connecting the IF-plate with the jig. We recognized, however, that the current screws doesn't have a vent-hole and are too long for the NAB-tower. So, Akutsu-san organized some shorter M5 screws (M5x20) with a vent-hole.
Also, the magnet-damper holders on the side of the NAB structure had to be removed. Otherwise, they would form an obstacle together with the jig's lateral beams. Due to difficulties in accessing the fixing-screws of the holders and taking-out the holders from the side, this work took us some while (we had to move the whole NAB structure sidewards for removing the holders first on one side and then on the other).
With these things done, we lifted the NAB out of the jig and carefully into the tower. While Akutsu-san was doing the lifting, Yano-san, Tanaka-kun, and I were taking care that the NAB is placed centered inside the tower.
Things we recognized when the NAB was placed:
- The M5 through-holes in the tower-beams for fixing the NAB to the tower are matching the respective screw-holes on the IF-plate only on one side (BS-side)! On the other side there is a mismatch of ~1-2mm sidewards! → We had this situation already in IXA... Also, the holes are not easily accessible with wrenches due to the T-beam structure of the beams
- The NAB itself seems to sit slightly obligued on the tower
- There is an indication line obviously not centered on the upper tower-beam and we have no clue what this means. Was the tower not centered inside the chamber from the beginning? Anyway, the NAB sits in the center of the tower somehow.
- There are also some indication lines on the tower's side-beams. When we do the final alignment, we will see what they actually mean...
Preparation for Tomorrow
We replaced the magnet-damper holders. This time, the mounting went much faster.
To realize a good fixing to the tower anyway, we moved carefully the NAB fully toward the side where the screws could get through (per design, there is a gap of ~4mm between IF-plate and beam-structure) and fixed it there. Then, we used the longitudinal slider of the NAB-structure to move the NAB (except the IF-plate) 4mm toward the other side, so that the NAB is again centered inside the tower. As for the lifting into the chamber, the side without screws is fixed temporarily with clamps.
As a last measure for today, we checked the lifting of the NAB+tower for tomorrows work. We are using two slings underneath the upper tower-beams. Their distance is fixed by a wooden bar (wrapped with white tape) similar to our doings during the NAB installation in IXA.