The end-cap had to sit between the muon chamber wheels and the rest of the detector, to a precision of 2mm and with a margin of 10cm on either side.
The 13m high, 240t end-cap had arrived on the doorstep of the ATLAS building on May 29, but it took another six days before it could cross the threshold. A slope in front of the building, designed to collect and drain rainwater, was preventing it from entering the building. The recess therefore had to be filled in and drains installed.
The wet weather conditions made the fill material unstable, so concrete blocks had to be installed on either side, and steel plates were laid on top of the fill material to reinforce the whole structure, raising it by a few centimetres.
“Because of this, we had to cut out one of the roof girders in the eaves to make room for the end-cap to pass through,” said Arnaud Foussat, project leader for the installation of the ATLAS toroid magnet end-cap.
