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

Phys. Rev. Lett.

98
122701
(2007)
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

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.

DOI
10.1103/PhysRevLett.98.122701
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