Critical aspects in the development of a curved fast ramped superconducting dipole for FAIR SIS300 synchrotron

The FAIR facility, under development at GSI, includes a large synchrotron for heavy ions acceleration: The SIS300, so called for having a magnetic rigidity of 300 Tm. The dipoles of this synchrotron shall be pulsed at the rate of 1 T/s up to 4.5 T maximum field in a bore of 100 mm. The magnets have a magnetic length ranging from 3.94m to 7.89 m with a cos-theta configuration. The coils with have the particular characteristic to be curved (the sagitta is 114 mm for the long dipoles). Design activities, coupled with conductor R&D and model coil construction, are under way for developing a curved fastcycled superconducting dipole, suitable for operations of the SIS300. The main goal is the construction, before the end of 2009, of a prototype magnet, including cold mass, fully integrated into a horizontal cryostat. An important intermediate milestone is the industrial feasibility assessment of the winding technology developed for a curve cos-theta dipole, through the construction of cured curved magnet poles, actually under way. The paper covers the critical aspects of this development, with particular emphasis on the constructive problems.