Coulomb Excitation of 68,70Cu: First Use of Post-accelerated Isomeric Beams

We report on the first low-energy Coulomb excitation measurements with radioactive 𝐼𝜋 =6− beams of odd-odd nuclei
68,70
Cu
. The beams were produced at ISOLDE, CERN and were post-accelerated by REX-ISOLDE to 2.83 MeV/nucleon. 𝛾 rays were detected with the MINIBALL spectrometer. The 6− beam was used to study the multiplet of states (3−, 4−, 5−, 6−) arising from the 𝜋⁢2⁢𝑝3/2⁢𝜈⁢1⁢𝑔9/2 configuration. The 4− state of the multiplet was populated via Coulomb excitation and the 𝐵⁡(𝐸⁢2;6− →4−) value was determined in both nuclei. The results obtained illustrate the fragile stability of the 𝑍 =28 shell and 𝑁 =40 subshell closures. A comparison with large-scale shell-model calculations using the
56
Ni
core shows the importance of the proton excitations across the 𝑍 =28 shell gap to the understanding of the nuclear structure in the neutron-rich nuclei with 𝑁 ≈40.

Authors: I. Stefanescu, G. Georgiev, F. Ames, J. Aysto, D.L. Balabanski, G. Bollen, P.A. Butler, J. Cederkäll, N. Champault, T. Davinson, A. De Maesschalck, P. Delahaye, J. Eberth, D. Fedorov, V.N. Fedosseev, L.M. Fraile, S. Franchoo, K. Gladnishki, D. Habs, K. Heyde, M. Huyse, O. Ivanov, J. Iwanicki, J. Jolie, B. Jonson, Th. Kröll, R. Krücken, O. Kester, U. Köster, A. Lagoyannis, L. Liljeby, G. Lo Bianco, B.A. Marsh, O. Niedermaier, T. Nilsson, M. Oinonen, G. Pascovici, P. Reiter, A. Saltarelli, H. Scheit, D. Schwalm, T. Sieber, N. Smirnova, J. Van De Walle, P. Van Duppen, S. Zemlyanoi, N. Warr, D. Weißhaar, F. Wenander

Doi: 10.1103/PhysRevLett.98.122701

Issue number:

Journal: Phys. Rev. Lett.

Page number: 122701

Published on: 2007-03-23

Year: