Considerations for a QD0 with Hybrid Technology in ILC

The baseline design of the QD0 magnet for ILC, the International Linear Collider, is a very compact superconducting quadrupole (coil-dominated magnet). A prototype of this quadrupole is under construction at Brookhaven National Laboratory (USA). In CLIC, the Compact Linear Collider under study at CERN, we are studying a different conceptual solution for the QD0. This is due to two main reasons: all the magnets of the Beam Delivery System will need to be stabilized in the nano-meter range and extremely tight alignment tolerances are required. The proposed solution, now baseline for CLIC, is a room temperature hybrid quadrupole based on resistive coils and permanent magnet blocks (iron-dominated magnet). In this paper we present a conceptual design for a hybrid solution studied and adapted also to the ILC project. A super-ferric solution (superconducting coils with warm iron poles) is proposed to make the cross section compatible with the layout of the experiments. This design matches the compactness requirement with the advantages of stability and alignment precision, aspects also critical for ILC in order to achieve its design luminosity. Final Focus optics design considerations for this solution are also presented.