Secondary beams and the synthesis of exotic nuclei

With the advent of modern fast cycling synchrotrons capable of delivering high intensity heavy ion beams up to uranium, the production of secondary radioactive ion beams (RIBs) with sufficient intensity has become feasible. The basic production mechanism is the fragmentation of near relativistic heavy ion beams on light targets. The physical facts underlying the efficient conversion of stable beams into RIBs are: (1) at beam energies of several 100 MeV/A thick conversion targets (1-10 g/cm2) can be used, which, for nuclei near stability, convert on the order of .1 to 1% of the primary beam into secondary beams, (2) the secondary beams are emitted into a narrow phase space (small transverse and longitudinal emittances), and (3) these emittances are of the correct magnitude to match the acceptances of suitably designed storage accumulator rings. From a primarily experimental point of view experiments with RIBs can be divided into three categories: (1) Experiments that measure properties of the secondary beams as such, like masses, Q-values, and magnetic moments, β-decay studies of implanted exotic nuclei, and Moessbauer spectroscopy. (2) Experiments that use external targets. This includes the synthesis of exotic nuclei with neutron- or proton-rich beams, implantation of RIBs for tracer studies in solid state physics, and biomedical applications. Many well established experimental techniques can be used in these two categories, while (3), the use of internal targets, represents in many ways new challenges to experimenters in nuclear and atomic physics