Low-loss NbTi Rutherford Cable for Application to the Development of SIS-300 Dipoles

INFN (Istituto Nazionale di Fisica Nucleare, Italy) has started in 2006 the DISCORAP project, which foresees the design, manufacture and test of a dipole prototype for the SIS-300 synchrotron of the FAIR facility at GSI. In order to minimize the losses produced by the fast ramp rate (1 T/s) at which the magnet is operated, we are developing with European industries, a Rutherford cable which incorporates several technologies to reduce the losses, and namely a NbTi filament diameter in the order of 2.5-3.5 μm, Cu 0.5wt%Mn interfilamentary matrix and stainless steel core. In this paper we present the design principles and the first experimental results. Special attention is paid to the analysis of the impact of the superconductor reversible and irreversible magnetization and of the CuMn paramagnetism on the field distortion at the different operating magnetic fields.