An important step for the ATLAS toroid magnet

The ATLAS experiment's prototype toroid coil arrives at CERN from the CEA laboratory in Saclay on 6 October.

The world's largest superconducting toroid magnet is under construction for the ATLAS experiment. A nine-metre long fully functional prototype coil was delivered to CERN at the beginning of October and has since been undergoing tests in the West Area. Built mainly by companies in France and Italy under the supervision of engineers from the CEA-Saclay laboratory near Paris and Italy's INFN-LASA, the magnet is a crucial step forward in the construction of the ATLAS superconducting magnet system.
Unlike any particle detector that has gone before, the ATLAS detector's magnet system consists of a large toroidal system enclosing a small central solenoid. The barrel part of the toroidal system will use eight toroid coils, each a massive 25 metres in length. These will dwarf the largest toroids in the world when ATLAS was designed, which measure about six metres. So the ATLAS collaboration decided to build an intermediate nine metre prototype coil to validate each step of the manufacturing process before embarking on the full-scale toroids. At each stage in the nine-metre toroid coil's manufacture, acquired know-how has fed directly into the manufacture of the larger toroids. Consequently, the first of those is already well advanced and due to be delivered to CERN late next year. By then, the nine-metre toroid coil will have completed its final task - as commissioning coil for the test set-up in the West Area where the full toroid system will be put through its paces before installation in the ATLAS experimental hall.