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High-precision mass measurements of nickel, copper, and gallium isotopes and the purported shell closure at N=40

C. Guenaut·G. Audi·D. Beck·K. Blaum·G. Bollen·P. Delahaye·F. Herfurth·A. Kellerbauer·H. -J. Kluge·J. Libert·D. Lunney·S. Schwarz·L. Schweikhard·C. Yazidjian
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Abstract

High-precision mass measurements of more than thirty neutron-rich nuclides around the Z=28 closed proton shell were performed with the triple-trap mass spectrometer ISOLTRAP at ISOLDE/CERN to address the question of a possible neutron shell closure at N=40. The results, for 57,60,64-69Ni (Z=28), 65-74,76Cu (Z=29), and 63-65,68-78Ga (Z=31), have a relative uncertainty of the order of 10^8. In particular, the masses of 72-74,76Cu have been measured for the first time. We analyse the resulting mass surface for signs of magicity, comparing the behavior of N=40 to that of known magic numbers and to mid-shell behavior. Contrary to nuclear spectroscopy studies, no indications of a shell or sub-shell closure are found for N=40.

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C. Guenaut, G. Audi, D. Beck, K. Blaum, G. Bollen, P. Delahaye, F. Herfurth, A. Kellerbauer, H. -J. Kluge, J. Libert, D. Lunney, S. Schwarz, L. Schweikhard, C. Yazidjian. 2007-01-22. High-precision mass measurements of nickel, copper, and gallium isotopes and the purported shell closure at N=40. https://doi.org/10.1103/physrevc.75.044303

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