A dual 6T persistent-mode SC solenoid ion-optical system for radioactive nuclear beam research

A unique ion-optical system for the production of high-intensity, short-lived radioactive nuclear beams has been designed, constructed and put into operation at the Nuclear Structure Laboratory at the University of Notre Dame as a joint project between the University of Michigan and NSL-UND. The system consists of a matched in-line pair of large-bore (30 cm) 6T superconductive solenoid magnets which act as high-acceptance collectors and magnetic filters of secondary radioactive nuclear beam (RNB) products. The latter are brought to a focus on a secondary target and nuclear reactions using the RNB studied. These are primarily reactions of interest in Big-Bang nucleosynthesis and stellar helium burning and involve the production of ⁶He, ⁷Be, ⁸B and similar beams. A number of unique features were incorporated in the magnet design to permit use as a precise ion-optical device in the RNB mode. To the authors´ knowledge this is the only large-scale in-beam ion-optical system to operate primarily in persistent mode. A similar device will also be built at the University of Sao Paulo for RNB research