A nuclear physics program at the Rare Isotope Beams Accelerator Facility in Korea

Abstract

This paper outlines the new physics possibilities that fall within the field of nuclear structure and astrophysics based on experiments with radioactive ion beams at the future Rare Isotope Beams Accelerator facility in Korea. This ambitious multi-beam facility has both an Isotope Separation On Line (ISOL) and fragmentation capability to produce rare isotopes beams (RIBs) and will be capable of producing and accelerating beams of wide range mass of nuclides with energies of a few to hundreds MeV per nucleon. The large dynamic range of reaccelerated RIBs will allow the optimization in each nuclear reaction case with respect to cross section and channel opening. The low energy RIBs around Coulomb barrier offer nuclear reactions such as elastic resonance scatterings, one or two particle transfers, Coulomb multiple-excitations, fusion-evaporations, and direct capture reactions for the study of the very neutron-rich and proton-rich nuclides. In contrast, the high energy RIBs produced by in-flight fragmentation with reaccelerated ions from the ISOL enable to explore the study of neutron drip lines in intermediate mass regions. The proposed studies aim at investigating the exotic nuclei near and beyond the nucleon drip lines, and to explore how nuclear many-body systems change in such extreme regions by addressing the following topics: the evolution of shell structure in areas of extreme proton to neutron imbalance; the study of the weak interaction in exotic decay schemes such as beta-delayed two-neutron or two-proton emission; the change of isospin symmetry in isobaric mirror nuclei at the drip lines; two protons or two neutrons radioactivity beyond the drip lines; the role of the continuum states including resonant states above the particle-decay threshold in exotic nuclei; and the effects of nuclear reaction rates triggered by the unbound proton-rich nuclei on nuclear astrophysical processes.

The impact of individual nuclear properties on r-process nucleosynthesis

“…In-flight projectile fragmentation involves collisions of nuclei at relativistic energies to produce the highly radioactive unstable fragments. The project in KORIA [203] plans to use both approaches of ISOL and fragmentation. There are advantages and disadvantages to both methods with the fragmentation approach allowing access to shorter half-lives while the ISOL method depending on the chemistry involved can produce more intense beams of potentially higher quality.…”

Nuclear structure and β -decay schemes for Te nuclides beyond N=82

“…Especially illuminating are the systematics of the first 2 + excited states of isotopic and isotonic chains which span the major shell closures. Figure 1 depicts such systematics of the even-even 46 ≤ Z ≤ 54 isotopes that show clear correlations between the 52 Te - 48 Cd and 54 Xe - 46 Pd isotopic chains [4]. + excited states in the nuclides around Sn (Z = 50) as a function of neutron number [4].…”

“…Figure 1 depicts such systematics of the even-even 46 ≤ Z ≤ 54 isotopes that show clear correlations between the 52 Te - 48 Cd and 54 Xe - 46 Pd isotopic chains [4]. + excited states in the nuclides around Sn (Z = 50) as a function of neutron number [4]. Data are primarily from [5], [6] for 126,128 Pd, [7] for 136,138 Sn, [8] for 138 Te, and the present work for 140 Te.…”

“…Fundamental characteristics of nuclear structure are best represented by systematic changes of experimental observables across the nuclear chart [1][2][3][4]. Especially illuminating are the systematics of the first 2 + excited states of isotopic and isotonic chains which span the major shell closures.…”