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 sc solenoid magnets which act as high-effeciency collectors and magnetic filters of secondary radioactive nuclear beam products (RNB). 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 our knowledge this is the only large-scale in-beam ion-optical system to operate primarily in persistent mode. A similar device will be built at the University of São Paulo also for RNB research. Index Terms – Superconducting solenoid ion-optical system, radioactive nuclear beam apparatus.