Present Status and Perspectives of RIBF

Abstract

The RIKEN Radioactive Isotope Beam Factory (RIBF) is a top world-class RIB facility, which was constructed to establish new framework of nuclear physics, to elucidate the origin of elements, and to explore new applications with fast RIBs. To achieve these goals, the RIBF facility consists of a high-power accelerator complex, a large-acceptance in-flight separator and unique devices to cover various experimental programs. As illustrated in Fig. 1, the accelerator complex consists of the old facility and a newly constructed one [1]. The old facility has a K540-MeV ring cyclotron (RRC) and two injectors, a variable-frequency heavy-ion linac (RILAC) and a K70-MeV AVF cyclotron. A new highpower heavy-ion booster system consisting of three ring cyclotrons with K = 570 MeV (fixed frequency, fRC), 980 MeV (intermediate stage, IRC), and 2600 MeV (superconducting, SRC), respectively, boost energies of the RRC beams up to 440 A MeV for light ions and 350 A MeV for very heavy ions. The goal of the primary beam intensity is set to be 1 pμA. At the end of 2006, the first primary beam was successfully accelerated at and extracted from SRC. The new in-flight separator BigRIPS [2] is to convert the SRC primary beams into RIBs. Combination of the high-power accelerator complex and the in-flight separator makes it possible to explore the limit of of nuclei and provides high yield rates of exotic nuclei. The RIBF facility has started delivering RI beams since 2007. In 2007, the first commissioning with a 350A MeV U beam successfully produced and identified two new isotopes, Pd, even with a low intensity of 0.03 pnA [3]. In November 2008, the second attempt to search for new isotopes was performed by utilizing the U beam with a 10 times higher intensity of 0.3 pnA and more than 40 of new isotopes were produced