Simultaneous impacts of nuclear shell structure and collectivity on β-decay: evidence from ⁸⁰Ga₄₉

The Gamow-Teller strength distribution covering the entire β-decay window, up to 10.312(4) MeV, of ⁸⁰ᵍ⁺ᵐGa was measured for the first time in photo-fission of UCₓ induced by 50 MeV electron beam. The new data show significant enhancement in the high-energy region with a jump-structure. Simultaneously, the γ de-exciting behavior of β-populated states presents a competition between de-excitation to 2₁⁺ [β₂ = 0.155(9)] and to 2₂⁺ [β₂ = 0.0530.0090.008)] in ⁸⁰Ge. Based on these facts and combined with a realistic shell model calculation and systematic analysis of logft ratio between precursor β-decay to 2₂⁺ and to 2₁⁺ of Ga isotopes, we conclude that these phenomena evidence simultaneous impacts of nuclear shell structure and collectivity on B(GT) and its distribution and, therefore, the half-life of the precursor. These data prove that the nucleus as a multi-nucleon correlated quantum system reacts as a whole when β-decay occurs in contrast to simple single-particle excitation. Additionally, the comparison with the theoretical results evidence how challenging is the description of the experimental data obtained, and render this experimental outcome a sound test for the theoretical models.