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Physical Review Letters 96 (2006) 012501
The N=14 shell closure in $^{22}$O viewed through a neutron sensitive probe
E. Becheva1, Y. Blumenfeld1, E. Khan1, D. Beaumel1, J. M. Daugas, F. Delaunay1, C.-E. Demonchy2, A. Drouart3, M. Fallot4, A. Gillibert3, L. Giot2, M. Grasso1, 5, N. Keeley3, K. W. Kemper, D. T. Khoa, V. Lapoux3, V. Lima1, A. Musumarra, L. Nalpas3, E. C. Pollacco3, O. Roig, P. Roussel-Chomaz2, J. E. Sauvestre, J. A. Scarpaci1, F. Skaza3, H. S. Than

To investigate the behavior of the N=14 neutron gap far from stability with a neutron-sensitive probe, proton elastic and 2+1 inelastic scattering angular distributions for the neutron-rich nucleus 22O were measured with a secondary beam intensity of only 1200 particles per second using the MUST silicon strip detector array at the GANIL facility. A phenomenological analysis yields a deformation parameter bp;p' = 0.26 +- 0.04 for the 2+1 state, much lower than in 20O, showing a surprisingly weak neutron contribution to this state. A fully microscopic analysis was performed using optical potentials obtained from matter and transition densities generated by continuum Skyrme-HFB and QRPA calculations, respectively. When the present results and those from a 22O + 197Au scattering experiment are combined, the ratio of neutron to proton contributions to the 2+1 state is found close to the N/Z ratio, demonstrating a strong N=14 shell closure in the vicinity of the neutron drip-line.
1 :  IPNO - Institut de Physique Nucléaire d'Orsay
2 :  GANIL - Grand Accélérateur National d'Ions Lourds
3 :  DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
4 :  SUBATECH - Laboratoire SUBATECH Nantes
5 :  LNS - Laboratori Nazionali del Sud
Physique/Physique Nucléaire Expérimentale
nuclear shell model – proton-nucleus reactions – nuclei with mass number 20 to 38 – nuclear forces – HF calculations – RPA calculations – nuclear optical model
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