Evidence for core excitation in single-particle states of 19Na

• Published in: Physics letters. B 2008-02, Vol.659 (5), p.864-869
• Main Authors: Pellegriti, M.G., Achouri, N.L., Angulo, C., Angélique, J.-C., Berthoumieux, E., Casarejos, E., Couder, M., Davinson, T., Ghag, C., Murphy, A.St, Orr, N.A., Ray, I., Stefan, I.G., Descouvemont, P.
• Format: Article
• Language: English
• Subjects: Elastic scattering; Exact sciences and technology; Inelastic scattering; Nuclear physics; Physics; Single-particle states; The physics of elementary particles and fields
• ISSN: 0370-2693; 1873-2445
• DOI: 10.1016/j.physletb.2007.12.017

We present an experimental study of 19Na states in the excitation energy range between 2 and 3 MeV. The presence of 19Na 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 18Ne radioactive beam on a (CH2)n target. The H(18Ne, p)18Ne(g.s.) and H(18Ne, p′)18Ne*(2+,1.887 MeV) cross sections have been obtained in the laboratory angular range θlab=6.1°–18.4° and analyzed by using the R-matrix method. Two new states in 19Na have been observed at centre-of-mass energies Ec.m.=2.78±0.01 MeV and 3.09±0.05 MeV. Both resonances exhibit large widths in the Ne18(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 Ne18(2+)+p structure.