Overview of RIBF and direct reactions with fast RI beams at RIBF

New-generation RI beam facilities such as RI Beam Factory (RIBF) will drastically enlarge the experimental opportunities to study the structure of unstable nuclei. In this field, direct-reaction measurements by the detection of the de-excitation $\gamma $ rays are the indispensable tools to probe the single particle and collective nature of the low-lying states. First, overview of RIBF and the BigRIPS Separator recently commissioned will be presented. Secondly, the experimental cases at RIBF with existing $\gamma $-ray detector arrays and advanced $\gamma $ -ray detector arrays will be discussed.