N = 14 and 16 shell gaps in neutron-rich oxygen isotopes

• Published in: Physical review. C, Nuclear physics Nuclear physics, 2004, Vol.69 (3), Article 034312
• Main Authors: Stanoiu, M., Azaiez, F., Dombrádi, Zs, Sorlin, O., Brown, B. A., Belleguic, M., Sohler, D., Saint Laurent, M. G., Lopez-Jimenez, M. J., Penionzhkevich, Y. E., Sletten, G., Achouri, N. L., Angélique, J. C., Becker, F., Borcea, C., Bourgeois, C., Bracco, A., Daugas, J. M., Dlouhý, Z., Donzaud, C., Duprat, J., Fülöp, Zs, Guillemaud-Mueller, D., Grévy, S., Ibrahim, F., Kerek, A., Krasznahorkay, A., Lewitowicz, M., Leenhardt, S., Lukyanov, S., Mayet, P., Mandal, S., van der Marel, H., Mittig, W., Mrázek, J., Negoita, F., De Oliveira-Santos, F., Podolyák, Zs, Pougheon, F., Porquet, M. G., Roussel-Chomaz, P., Savajols, H., Sobolev, Y., Stodel, C., Timár, J., Yamamoto, A.
• Format: Article
• Language: English
• Subjects: drip-line; magic number; n=20; nuclei; o-28; projectile fragmentation; spectroscopy; stability; state
• ISSN: 0556-2813; 1089-490X; 1089-490X
• DOI: 10.1103/PhysRevC.69.034312

In-beam gamma-ray spectroscopy using fragmentation reactions of both stable and radioactive beams has been performed in order to study the structure of excited states in neutron-rich oxygen isotopes with masses ranging from A=20 to 24. For the produced fragments, gamma-ray energies, intensities, and gamma-gamma coincidences have been measured. Based on this information new level schemes are proposed for O-21,O-22 up to the neutron separation energy. The nonobservation of any gamma-decay branch from O-23 and O-24 suggests that their excited states lie above the neutron decay thresholds. From this, as well as from the level schemes proposed for O-21 and O-22, the size of the N=14 and 16 shell gaps in oxygen isotopes is discussed in the light of shell-model calculations.