The Euroschool Lectures on Physics with Exotic Beams, Vol. I - In-flight separation of projectile fragments

Abstract

The in-flight or direct production of secondary beams of radioactive ions is discussed. Two reaction mechanisms, fragmentation and fission of fast projectiles, have been shown to be very effective at producing beams of an extremely broad range of interesting nuclei. The resulting nuclei have large forward momenta with relatively sharp angular distributions peaked close to zero degrees. Such narrow distributions are readily collected and purified with magnetic devices by exploiting atomic energy-loss processes in profiled energy degraders. With large aperture magnets and high energy primary beams, collection of nearly the full momentum and angular distribution of a given fragment are now possible, although the beam emittance may be poor and depends on the production mechanism. The features of the production reaction mechanisms, separation techniques, and a survey of the present and proposed devices are presented.