Journal Article

Measurement and microscopic description of odd–even staggering of charge radii of exotic copper isotopes

Stroke, H. H., Day Goodacre, T., Holt, J. D., Miyagi, T., Billowes, J., Farooq-Smith, G. J., Yang, X. F., Gins, W., Franchoo, S., Fedorov, D. V., Rothe, S., Neyens, G., Bissell, M. L., de Groote, R. P., Garcia Ruiz, R. F., Flanagan, K. T., Reinhard, P.-G., Nazarewicz, W., Wilkins, S. G., Koszorús, Á., Vernon, A. R., Xu, Z. Y., Binnersley, C. L., Cocolios, T. E., Lynch, K. M., Wendt, K. D. A.

2020

Overview

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 78 Cu (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 ≤ 4 nuclei. 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.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Publishing Group [2005-....],Nature Publishing Group (NPG)
• Subject: 639/766/387/1126 / 639/766/387/1129 / Atomic / Atomic properties / Classical and Continuum Physics / Complex Systems / Condensed Matter Physics / Copper / Copper isotopes / Density / experimental nuclear physics / Ionization / Letter / Mathematical and Computational Physics / Molecular / Neutrons / Nuclear Experiment / Nuclear matter / NUCLEAR PHYSICS AND RADIATION PHYSICS / Nuclear Theory / Optical and Plasma Physics / Physics / Physics and Astronomy / Protons / Reduction / Separators / Staggering / Theoretical / theoretical nuclear physics