  Exotic beams of short-lived radioisotopes are produced in nuclear reactions
such as thermal neutron induced fission, target or projectile fragmentation and
fusion reactions. For a given radioactive ion beam (RIB), different production
modes are in competition. For each of them the cross section, the intensity of
the projectile beam and the target thickness define an upper production rate.
The final yield relies on the optimisation of the ion-source, which should be
fast and highly efficient in view of the limited production cross section, and
on obtaining a minimum diffusion time out of the target matrix or fragment
catcher to reduce decay losses. Eventually, either chemical or isobaric
selectivity is needed to confine unwanted elements near to the production site.
These considerations are discussed for pulsed or dc-driven RIB facilities and
the solutions to some of the technical challenges will be illustrated by
examples of currently produced near-drip-line elements.
