Speaker
Description
In-beam γ-ray spectroscopy with fast radioactive beams is a powerful approach for exploring nuclear structure far from stability, particularly at high-intensity rare-isotope facilities such as RIKEN’s Radioactive Isotope Beam Factory (RIBF). Using the high-efficiency DALI2+ array, we have investigated nuclear collectivity across several key regions of the nuclear chart employing inelastic scattering, quasi-free scattering, and nucleon knockout reactions. These studies have yielded a number of notable results, including enhanced deformation in the island of inversion around 32Mg, evidence for mirror symmetry in proton-rich krypton isotopes, and systematic investigations of collectivity in the vicinity of the doubly magic nuclei 100Sn and 132Sn. More recently, we have extended these measurements to the calcium isotopes near the proposed new magic numbers N = 32 and 34.
For experiments requiring higher gamma-ray energy resolution, we have employed the high-purity germanium array HiCARI. Using inelastic scattering and Doppler-corrected line-shape analyses, we have studied quadrupole deformation in neutron-rich Ge, Se, Mo, and Zr isotopes, providing complementary and more detailed insights into collective phenomena.
Looking ahead, we are developing HYPATIA, a next-generation in-beam γ-ray spectrometer based on fast scintillators (GAGG and CeBr3), designed to combine high efficiency, fast timing, and good energy resolution. HYPATIA will gradually replace DALI2, offering increased granularity, improved timing performance, and enhanced efficiency, thereby significantly extending the reach of in-beam spectroscopy at the RIBF.
In this presentation, I will give an overview of these ongoing activities, highlight selected recent results, and outline future directions of our in-beam γ-ray spectroscopy program.