Nuclear physics with radioactive beams

Abstract

Radioactive beams can be produced through two different and complementary ways: firstly by the production of radioactive nuclei at rest, followed by their acceleration using conventional techniques. This method is the best for producing low-energy radioactive beams. The second method is by the fragmentation of high-energy heavy ion beams (over 30 MeV/u), followed by the selection and purification of a given secondary beam using magnetic spectrometers. This technique leads to high-energy radioactive beams. Both methods have now been used in several laboratories in the World (Berkeley, Ganil, Louvain la Neuve, Riken, GSI Darmstadt). Examples of the corresponding experimental equipment are presented, and especially Lise 3, Sissi and the Spiral project at Ganil. Radioactive beams have been used for several purposes in nuclear physics. They constitute the fastest technique ever used for transferring exotic nuclei from the production point to a well-shielded place where detectors can be operated for studying their properties. They are used to induce nuclear reactions which reveal new information on nuclear structure. In the domain of nuclear astrophysics, radioactive beams are used to measure, through direct or indirect methods, the cross sections for reactions of crucial interest in nucleosynthesis. Finally, radioactive beams of light positron emitters, such as 19Ne have considerable interest for medical purposes and especially in the growing field of heavy-ion radiotheraphy.