Studies with beams of unstable nuclei have greatly developed in the fields of nuclear structure physics and nuclear astrophysics. At RIKEN, beams of unstable nuclei with a few tens MeV/nucleon energies have been provided since 1990. For many light unstable nuclei, their beams are available with the world's highest intensity. Variety of studies have been performed on particle-stability in the vicinity of the neutron drip-line, properties of neutron halo and skin, appearance and disappearance of magic numbers, and decoupling of neutron and proton motion. Nuclear astrophysics studies have also been made with direct and indirect methods for nuclear burning processes involving unstable nuclei. Some recent results will be presented.
Currently a new project to build a next-generation facility for RI (Radioactive Isotope) beams is in progress at RIKEN. Its basic part (accelerators and an RI beam separator called BigRIPS) of this RI Beam Factory (RIBF) is now under construction and will be commissioned during the year 2006. In-flight fission of a 350~MeV/nucleon primary beam of uranium will be used as well as projectile fragmentation of ions, such as those of Xe, Kr and Ca. The RIBF is designed to provide much wider range of RI beams with higher intensities compared with existing facility including the present RIKEN accelerator complex. We aimed at greatly extending the region of nuclei to be studied. Together with other new generation facilities like RIA, FAIR and Spiral2, we hope that a new and comprehensive picture for the nuclear system is established and the mechanism of creating chemical elements in the universe is clarified.
