High-resolution spectroscopy of exotic nuclei to study NN and 3N interactions

原子核是一个量子多体系统，其中质子和中子受到复杂的神经网络相互作用的影响，包括中心、自旋轨道、张量和多体（例如3N）的贡献。外来核中的核结构的改变是由这些神经网络相互作用的特定成分驱动的，通过实验研究非常外来的核，我们可以确定哪些成分负责外来核的不同特征。这些现象的研究需要测量外来核激发态的关键光谱信息，而RIKEN的新HiCARI项目提供了一个令人兴奋的机会，可以在核稳定的极端状态下对原子核进行测量。特别是，我们将研究非常富中子的20C核素的2+激发态的寿命，其中张量和两体自旋轨道力负责Z=6自旋轨道壳隙的侵蚀。同时，激发态的寿命对3N力非常敏感，这种在滴线上的测量将使我们对3N相关性如何在同位旋的极端情况下驱动壳层演化有一个独特的见解。我们将对78Ni进行详细的光谱分析，它的双重魔力已经被证实[nature 569, 53 (2019)]；然而，这些结果表明，一个潜在的变形状态靠近球形状态，这标志着78Ni以外的核结构发生了改变。我们将首次测量富中子Ca同位素的寿命，这是现象学和从头计算的关键试验场，在那里我们将能够阐明3N力的影响。我们将测量最重的可达N=Z核88Ru和86Tc的激发态寿命，以阐明在这些奇异系统中预测存在的一种特殊类型的中子-质子配对相关（等标量）的作用，并预测它会影响这些测量。

The atomic nucleus is a quantum many-body system, where protons and neutrons are subject to complex NN interactions that include central, spin-orbit, tensor and many-body (e.g. 3N) contributions. The modification of nuclear structure in exotic nuclei is driven by specific components of these NN interactions and by studying experimentally very exotic nuclei, we can identify which component is responsible for distinct features of exotic nuclei. The study of these phenomena requires measurement of key spectroscopic information on excited states of exotic nuclei, and the new HiCARI campaign at RIKEN provides an exciting opportunity to do so in nuclei at the extremes of nuclear stability. In particular, we will study the lifetime of the 2+ excited state of the very neutron-rich 20C nuclide, where tensor and two-body spin-orbit forces are responsible for the erosion of the Z=6 spin-orbit shell gap. At the same time, lifetimes of excited states are very sensitive to 3N forces and such measurements at the dripline will give us a unique insight on how 3N correlations drive the shell evolution at the extremes of isospin. We will perform detailed spectroscopy of 78Ni, whose doubly magic nature has been confirmed [Nature 569, 53 (2019)]; these results, however, show a potential deformed state lying close to the spherical one, signaling a modification of nuclear structure beyond 78Ni. We will measure for the first time lifetimes in neutron-rich Ca isotopes, a critical testing ground for phenomenology and ab initio calculations, where we will be able to shed light into 3N force effects. We will measure lifetimes of excited states in the heaviest accessible N=Z nuclei 88Ru and 86Tc to shed light on the role of a special type of neutron-proton pairing correlation (isoscalar) predicted to exist in these exotic systems and which is predicted to impact on these measurements.