Evolution of the nuclear structure in neutron-rich Cu isotopes; First spectroscopy of odd-odd Cu and Cu

中性子過剰なCu同位体における原子核構造の進化; 奇奇核CuおよびCuの初の分光測定

Pedersen, L. G.*; Sahin, E.*; Orlandi, R.   ; 他64名*

Pedersen, L. G.*; Sahin, E.*; Orlandi, R.; 64 of others*

This study reports the first spectroscopic observation of excited states in odd-odd isotopes Cu and Cu, following Ni decay. Performed at RIKEN, the experiment analyzed -ray coincidences to construct level schemes for these nuclei. The findings interpret the low-lying states as spin multiplets resulting from the coupling of specific single-particle orbitals (protons and neutrons). The results provide crucial data on how single-particle orbitals evolve in neutron-rich Cu isotopes and characterize the proton-neutron interaction near Ni. Furthermore, they constitute key benchmarks for nuclear structure theory, detailing orbital evolution in neutron-rich Cu. Most significantly, the non-observation of a predicted isomer, combined with observed decays, definitively assigns the spin-parity ( vs ), resolving long-standing ambiguities for advanced shell-model calculations.