News Physics Colloquium at 4:30 pm, today at Room 216-1 “Spectroscopy of neutron rich nuclei at RIKEN-RIBF” Prof. Yoshiteru Sato (SNU) Abstract According to theoretical estimates, about 10,000 different short-lived radioactive isotopes are expected to exist in nature; of these, only about one third have been experimentally confirmed so far. Once a new isotope is discovered, its properties, such as mass, radioactive half-life, electromagnetic moment, and spectrum of excited states, can be studied. This information is not only useful for the development of a comprehensive, predictive theory of complex nuclei, but also for the elucidation of the origin of elements & abundances of matter in the universe, and the mechanism of energy generation in stars. The major goals of radioactive isotope beam facilities worldwide are to address these issues. In this talk, firstly, a brief introduction of the RIKEN RI Beam Factory (RIBF), which recently came into regular operation following a major, ten-year-long upgrade program, will be given. Emphasis is placed on the discovery of 47 new isotopes with the newly commissioned BigRIPS fragment separator. Secondly, I will focus on experiments that search for unbound excited states in neutron-rich nuclei. A novel experimental technique called the invariant mass method in inverse kinematics has been successfully used to identify new resonant nuclear states in a number of light neutron-rich nuclei such as 19C, 17C, 14B, and 13Be. The consequence of each study will be presented, together with a perspective of the study at RIBF Trigger 1