The N=14 shell closure in $^{22}$O viewed through a neutron sensitive probe

E. Becheva (1) , Y. Blumenfeld (1) , E. Khan (1) , D. Beaumel (1) , J.M. Daugas , F. Delaunay (1) , C.E. Demonchy (2) , A. Drouart (3) , Muriel Fallot (4) , A. Gillibert (3) , Lydie Giot (2) , M. Grasso (1, 5) , N. Keeley (3) , K.W. Kemper , D.T. Khoa , V. Lapoux (3) , V. Lima (1) , A. Musumarra , L. Nalpas (3) , E.C. Pollacco (3) , O. Roig , P. Roussel-Chomaz (2) , J.E. Sauvestre , J. A. Scarpaci (1) , F. Skaza (3) , H.S. Than

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

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.

Mots clés: nuclear shell model; proton-nucleus reactions; nuclei with mass number 20 to 38; nuclear forces; HF calculations; RPA calculations; nuclear optical model

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

E. Becheva, Y. Blumenfeld, E. Khan, D. Beaumel, J.M. Daugas, et al.. The N=14 shell closure in $^{22}$O viewed through a neutron sensitive probe. Physical Review Letters, 2006, 96, pp.012501. ⟨10.1103/PhysRevLett.96.012501⟩. ⟨in2p3-00025255⟩