Overview and status of the Next European Dipole Joint Research Activity

The Next European Dipole (NED) Joint Research Activity was launched on 1 January 2004 to promote the development of high-performance Nb₃Sn conductors in collaboration with European industry (aiming at a non-copper critical current density of 1500A mm^-2 at 4.2 K and 15 T) and to assess the suitability of Nb₃Sn technology to the next generation of accelerator magnets (aiming at an aperture of 88 mm and a conductor peak field of ∼15 T). It is part of the Coordinated Accelerator Research in Europe (CARE) project, which involves eight collaborators, and is half-funded by the European Union. After briefly recalling the Activity organization, we report the main progress achieved over the last year, which includes: the manufacturing of a double-bath He II cryostat for heat transfer measurements through Nb ₃Sn conductor insulation, detailed quench computations for various NED-like magnet configurations, the award of two industrial subcontracts for Nb₃Sn conductor development, the first results of a cross-calibration programme of test facilities for Nb₃Sn wire characterization, detailed investigations of the mechanical properties of heavily cold-drawn Cu/Nb/Sn composite wires, and the preliminary assessment of a new insulation system based on polyimide-sized glass fibre tapes. Last, we briefly review the efforts of an ongoing Working Group on magnet design and optimization.