Measurement and microscopic description of odd-even staggering of charge radii of exotic copper isotopes
Measurement and microscopic description of odd-even staggering of charge radii of exotic copper isotopes
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DOI：
10.1038/s41567-020-0868-y
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发表时间：
2020-04-13
期刊：
影响因子：
19.6
通讯作者：
Yang, X. F.
中科院分区：
文献类型：
--
作者：
de Groote, R. P.;Billowes, J.;Yang, X. F.
具有奇数中子的同位素通常比它们的偶数中子邻居的尺寸略小。在短寿命铜同位素的电荷半径中，当中子数接近50时，这种效应会减弱。核电荷半径与原子质量数A的整体比例为A（1/3），并且具有奇数中子数的同位素通常比其偶数中子邻居的尺寸略小。这种奇异的现象在整个核领域中普遍存在（1），随着质子和中子的数量而变化，并对核理论提出了重大挑战（2-4）。在这里，我们报告的电荷半径的短寿命的铜同位素的测量非常奇特的Cu-78（质子数Z = 29和中子数N = 49），产生在只有20个离子s（-1），使用共线共振电离光谱法在同位素质量分离器在线设备设施（ISOLDE）在欧洲核子研究中心。我们观察到一个意想不到的减少，在奇数-偶数交错接近N = 50壳间隙的同位素。为了描述数据，我们应用了基于核密度泛函理论（5，6）和A体价空间介质相似性重整化群理论（7，8）的模型。通过这些比较，我们证明了电荷半径的整体行为与核物质饱和密度之间的关系，并表明反映多体极化效应的局域电荷半径变化自然地出现在适合于A性质的A体计算中
Isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. In charge radii of short-lived copper isotopes, a reduction of this effect is observed when the neutron number approaches fifty.Nuclear charge radii globally scale with atomic mass number A as A(1/3), and isotopes with an odd number of neutrons are usually slightly smaller in size than their even-neutron neighbours. This odd-even staggering, ubiquitous throughout the nuclear landscape(1), varies with the number of protons and neutrons, and poses a substantial challenge for nuclear theory(2-4). Here, we report measurements of the charge radii of short-lived copper isotopes up to the very exotic Cu-78 (with proton number Z = 29 and neutron number N = 49), produced at only 20 ions s(-1), using the collinear resonance ionization spectroscopy method at the Isotope Mass Separator On-Line Device facility (ISOLDE) at CERN. We observe an unexpected reduction in the odd-even staggering for isotopes approaching the N = 50 shell gap. To describe the data, we applied models based on nuclear density functional theory(5,6) and A-body valence-space in-medium similarity renormalization group theory(7,8). Through these comparisons, we demonstrate a relation between the global behaviour of charge radii and the saturation density of nuclear matter, and show that the local charge radii variations, which reflect the many-body polarization effects, naturally emerge from A-body calculations fitted to properties of A