First Evidence of Shape Coexistence in the Ni-78 Region: Intruder 0(2)(+) State in Ge-80

The N = 48 Ge-80 nucleus is studied by means of beta-delayed electron-conversion spectroscopy at ALTO. The radioactive Ga-80 beam is produced through the isotope separation on line photofission technique and collected on a movable tape for the measurement of gamma and e(-) emission following beta de...

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Bibliographic Details
Published in:Physical review letters 2016-05, Vol.118 (issue 18)
Main Authors: Gottardo, A., Verney, D., Delafosse, C., Ibrahim, F., Roussiere, B., Sotty, C., Roccia, S., Andreoiu, C., Costache, C., Delattre, M., Deloncle, I., Etile, A., Franchoo, S., Gaulard, C., Guillot, J., Lebois, M., Maccormick, M., Marginean, N., Marginean, R., Matea, I., Mihai, C., Mitu, I., Olivier, L., Portail, C., Qi, L., Stan, L., Testov, D., Wilson, J., Yordanov D., T.
Format: Article
Language:English
Subjects:
Nuclear Experiment
Physics
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Summary:The N = 48 Ge-80 nucleus is studied by means of beta-delayed electron-conversion spectroscopy at ALTO. The radioactive Ga-80 beam is produced through the isotope separation on line photofission technique and collected on a movable tape for the measurement of gamma and e(-) emission following beta decay. An electric monopole E0 transition, which points to a 639(1) keV intruder 0(2)(+) state, is observed for the first time. This new state is lower than the 2(1)(+) level in Ge-80, and provides evidence of shape coexistence close to one of the most neutron-rich doubly magic nuclei discovered so far, Ni-78. This result is compared with theoretical estimates, helping to explain the role of monopole and quadrupole forces in the weakening of the N = 50 gap at Z = 32. The evolution of intruder 0(2)(+) states towards Ni-78 is discussed.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.116.182501