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Physics Letters B 659 (2008) 864-869
Evidence for core excitation in single-particle states of $^{19}$Na
M.G. Pellegriti1, N.L. Achouri2, C. Angulo1, J.C. Angélique2, E. Berthoumieux3, E. Casarejos1, M. Couder1, T. Davinson4, C. Ghag4, A.St. Murphy4, N.A. Orr2, I. Ray5, I.G. Stefan5, P. Descouvemont6

We present an experimental study of $^{19}$Na states in the excitation energy range between 2 and 3 MeV. The presence of $^{19}$Na single-particle levels at these energies was first predicted by a microscopic cluster model and then experimentally confirmed by measuring the elastic and inelastic scattering of a 66 MeV $^{18}$Ne radioactive beam on a $(CH2)_n$ target. The H($^{18}$Ne,p)$^{18}$Ne(g.s.) and H($^{18}$Ne,p')18Ne*($2^+$, 1.887 MeV) cross sections have been obtained in the laboratory angular range $\theta$_lab$ = 6.1°−18.4° and analyzed by using the R-matrix method. Two new states in $^{19}$Na have been observed at centre of mass energies $E_c.m.$ = 2.78 ± 0.01 MeV and 3.09 ± 0.05 MeV. Both resonances exhibit large widths in the $^{18}$Ne($2^+$)+p channel, and low branching ratios into the elastic channel. The reduced proton widths confirm the single-particle nature of these states, with a $^{18}$Ne($2^+$)+p structure.
1 :  Centre de Recherches du Cyclotron and Institut de Physique Nucléaire
2 :  LPCC - Laboratoire de Physique Corpusculaire de Caen
3 :  DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée
4 :  Department of Physics and Astronomy
5 :  GANIL - Grand Accélérateur National d'Ions Lourds
6 :  Physique Nucléaire Théorique et Physique Mathématique
structure nucléaire
Physique/Physique Nucléaire Expérimentale
Elastic scattering – Inelastic scattering – Single-particle states
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19na.pdf(276.8 KB)