Radioactive nuclear beam facilities based on projectile fragmentation

摘要

The production of radioactive ions by using direct in-flight separation techniques is discussed. The reaction mechanisms used to produce radioactive beams near projectile velocities can be broadly divided into four classes: projectile fragmentation, nucleon transfer, fission, and Coulomb excitation. Radioactive nuclei produced by these reactions have large forward momenta with relatively sharp angular distributions peaked close to zero degrees. Such narrow distributions are suitable for collection with magnetic devices. Further beam purification can be achieved by exploiting atomic energy-loss processes in profiled energy degraders combined with a second magnetic selection. Secondary beam intensities of up to 1%, or so, of the primary beam intensity are possible, although the beam emittance depends on the production mechanism and may be poor. The features of the production reaction mechanisms, separation techniques, and a review of worldwide efforts are presented. Also the relative advantages and disadvantages of the method are discussed along with techniques that can be used to overcome some of the disadvantages. [References: 75]