Abstract. The use of unstable nuclei in the form of energetic beams for nuclear physics studies is now entering into a new era. "New-generation" facilities are either in operation, under construction or being planned. They are designed to provide radioactive isotope (RI) beams with very high intensities over a wide range of nuclides. These facilities are expected to provide opportunities to study nuclear structure, astrophysical nuclear processes and nuclear matter with large proton-neutron imbalance in grate detail. This article reports on the current status of such new-generation RI-beam facilities around the world.
RI beams in nuclear physics studies
Extension of our knowledge in the nuclear chartRadioactive isotopes (RI), or unstable nuclei, play a crucial role in enhancing our knowledge on atomic nuclei. The discovery of new methods for artificial RI production has advanced nuclear physics research substantially. A total of around 500 isotopes were known in 1940, including almost 300 stable ones. The number of known nuclides has increased in a linear manner since then, with some variations due to social constraints or technical innovations [1]. The nuclear chart, shown in Fig. 1, exhibits the present status of our knowledge. About 3,000 isotopes including 2,700 radioactive ones have been identified so far. According to theoretical predictions by, for example, the KTUY theory [2], another 7,000 isotopes might exist if fissioning nuclei with lifetimes longer than 1 µs are counted as well as β emitters [3]. The effort to extend our knowledge on the nuclear chart is an ongoing process: construction of new facilities and development of new experimental methods should support such activities.
Development of RI beamsIn the mid 80s, the idea of using unstable nuclei in the form of energetic beams was realized for the first time at LBL [4]. The projectile-fragmentation reaction with fast ion-beams was the mechanism to produce RI's in-flight. The first application of these RI beams was to measure interaction cross sections of light unstable nuclei. The enhancement of matter radius owing to neutron halos was observed for some light, neutron-rich nuclei. This success triggered the construction of new facilities that could provide RI beams with high intensities using the same production method. In the 90's, dedicated a