Structure of $^{12}$Be : intruder d-wave strength at N=8

S.D. Pain , W.N. Catford (1) , N.A. Orr (1) , J.C. Angélique (1) , N.I. Ashwood , V. Bouchat , N. M. Clarke , N. Curtis , M. Freer , B. R. Fulton , F. Hanappe , M. Labiche , J.L. Lecouey (1) , R. C. Lemmon , D. Mahboub , A. Ninane , G. Normand (1) , N. Soic , L. Stuttge (2) , C. N. Timis , J. A. Tostevin , J.S. Winfield (1) , V. Ziman

1 LPCC - Laboratoire de physique corpusculaire de Caen
2 IReS - Institut de Recherches Subatomiques

The breaking of the N=8 shell-model magic number in the $^{12}$Be ground state has been determined to include significant occupancy of the intruder d-wave orbital. This is in marked contrast with all other N=8 isotones, both more and less exotic than $^{12}$Be. The occupancies of the 0hw vp$_{1/2}$ orbital and the 1hw, vd$_{5/2}$ intruder orbital were deduced from a measurement of neutron removal from a high-energy $^{12}$Be beam leading to bound and unbound states in $^{11}$Be.

Domaines: Physique Nucléaire Expérimentale [nucl-ex]

S.D. Pain, W.N. Catford, N.A. Orr, J.C. Angélique, N.I. Ashwood, et al.. Structure of $^{12}$Be : intruder d-wave strength at N=8. Physical Review Letters, 2006, 96, pp.032502. ⟨10.1103/PhysRevLett.96.032502⟩. ⟨in2p3-00025637⟩