Manufacturing aspects of the ATLAS barrel toroid double pancakes

In 1999 INFN (Istituto Nazionale di Fisica Nucleare) ordered to ANSALDO the manufacturing of 16 double pancakes for the ATLAS BARREL TOROID. In July 2001 four Double Pancakes have already been completed and shipped to the integration site. In this paper the main aspects of the manufacturing of the largest superconducting coils ever built (5×25 m) are described. The main phases of the manufacturing procedure are reviewed starting from the conductor preparation to the VPI impregnation, including references to the materials used as well as to the relevant customer´s requirements. In particular the special winding form and the winding technique are treated. For each phase the most critical aspects and the relevant solutions are pointed out. Particular details about the technical solutions adopted for the impregnation and curing of the Double Pancake, which could not be performed inside an autoclave due to the huge dimension of the coil itself, are reported. Finally the methods used for the dimensional and electrical tests are described and the results obtained on the first double pancakes are analyzed.