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NN相互作用，包括中心，自旋轨道，张量和多体（例如3 N）贡献。奇异核的核结构的修改是由这些NN相互作用的特定组件驱动的，通过研究实验非常奇异的核，我们可以确定哪个组件是负责奇异核的独特特征。对这些现象的研究需要测量奇异核激发态的关键光谱信息，而RIKEN的新HiCARI活动为在核稳定性极端的核中这样做提供了一个令人兴奋的机会。特别是，我们将研究的2+激发态的非常丰富的中子20 C核素，张量和两体自旋轨道力的Z=6自旋轨道壳隙的侵蚀负责的寿命。与此同时，激发态的寿命对3 N力非常敏感，在滴线上的这种测量将使我们对3 N相关性如何在同位旋的极端情况下驱动壳层演化有独特的见解。我们将对78 Ni进行详细的光谱分析，其双重魔法性质已得到证实[Nature 569，53（2019）];然而，这些结果显示了一个潜在的变形状态，接近球形状态，表明78 Ni以外的核结构发生了变化。我们将首次测量富含中子的Ca同位素的寿命，这是现象学和从头计算的关键测试场，在那里我们将能够揭示3 N力效应。我们将测量最重的N=Z原子核88 Ru和86 Tc中激发态的寿命，以阐明预测存在于这些奇异系统中的一种特殊类型的中子-质子配对相关（isoscillation）的作用，并预测对这些测量产生影响。

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.