Session 4WFB: Science of Intense High Energy Rare Isotope Beams II

Decay spectroscopy of exotic nuclei at RIBF

The advent of radioactive ion beam facilities, such as RIBF at RIKEN and FRIB at MSU, is expected to grant nuclear physics access to the study of unstable nuclei, ranging from proton drip line to neutron-rich nuclei close to the astrophysical r-process path. Nuclear decay is a common process for most of the unstable nuclei that decay into more stable forms via the emission of beta particles, alpha particles, protons, and neutrons, with the exception of heavier nuclei that undergo fission.

Nuclear decay spectroscopy has emerged as a crucial tool for examining these exotic nuclei, especially where the production yield at RI beam facilities is insufficient for reaction-based studies. At RIBF, a diverse array of decay spectroscopy setups has been implemented, including isomer and beta-gamma spectroscopy (EURICA), beta-delayed neutron branching ratio measurement (BRIKEN), beta-delayed neutron spectroscopy (VANDLE), alpha-decay measurement, two-proton radioactivity, and others. These experiments have charted various regions of the nuclear landscape and provided systematic data that provide unique insight into the nuclear shell structure, collective properties such as deformation, and astrophysical nucleosynthesis.

This talk will offer an overview of decay spectroscopy at RIBF and suggest potential avenues for future experiments.   

The ESPRI project at RIBF

Proton elastic scattering at intermediate energy is the most fundamental probe to study both nuclear structures and nuclear reactions. Based on the microscopic optical model within the relativisitc framwork, the proton and neutron density profiles are found to be directly determined by the angular distributions of the cross sections. Precise extractions of the density distributions make it possible to understand the roll of the isospin in the nuclear many-body system. Particularly, the asymmetric nuclear matter EOS is one of the highlights of this research. We have already started an experimental project of the proton elastic scatternig from unstable nuclei to extend our knowledge to the system with large isospin asymmetry. The so-called ESPRI project is now in progress at RIBF, which can provide the highest-intensity RI beams in the world. I will talk about the results and the future plans.