The superconducting magnet components of the large acceptance QQD spectrometer ALADiN

A magnetic spectrometer system for the investigation of projectile fragmentation and nuclear reactions in inverse kinematics consists of independent elements for focusing (two superconducting quadrupole magnets) and momentum analysis (one superconducting dipole magnet as its major component). The dipole magnet consists of two superconducting solenoid coils symmetric to the midplane with pole pieces at room temperature outside the coil vacuum chambers and a large iron yoke to return the magnetic flux. The most important parameters are summarized. Optimizations with the 3-dimensional magnet program TOSCA yielded a total current of 4*10⁶ A which produces a central field of 4.2 T in the dipole magnet with H-shaped iron yoke; the stored energy is approximately=21 MJ. The force acting between the iron plates is approximately=1.5*10⁶ MPa. The forces were estimated with the two-dimensional computer code POISSON. The authors review design considerations for the coils, special requirements demanded of the superconductor, and quench protection for the magnet.