Level structure of Mg21: Nuclear and astrophysical implications
Resonant elastic scattering of a radioactive $^{20}\mathrm{Na}$ beam incident upon protons in a polyethylene target has been used to probe the level structure of $^{21}\mathrm{Mg}$ above the proton decay threshold. Three states have been observed, and their properties deduced through analysis based on the R-matrix formalism. The results improve and extend previous studies of this nucleus. An estimate of the $^{20}\mathrm{Na}$(p,\ensuremath{\gamma})$^{21}\mathrm{Mg}$ reaction rate, including these new data, suggests this reaction will not play a significant role in explosive hydrogen burning in astrophysical sites such as novae and x-ray bursts.
Nuclear Astrophysics with Radioactive Beams
The quest to comprehend how nuclear processes influence astrophysical phenomena is driving experimental and theoretical research programs worldwide. One of the main goals in nuclear astrophysics is to understand how energy is generated in stars, how elements are synthesized in stellar events and what the nature of neutron stars is. New experimental capabilities, the availability of radioactive beams and increased computational power paired with new astronomical observations have advanced the present knowledge. This review summarizes the progress in the field of nuclear astrophysics with a focus on the role of indirect methods and reactions involving beams of rare isotopes.
Proton single-particle states in [sup 21,23]Na through the ([ital d],[ital n]) reaction
Proton single-particle states in [sup 21,23]Na were studied through the ([ital d],[ital n]) reaction on [sup 20,22]Ne at [ital E][sub [ital d]]=25 MeV. Angular distributions of the emitted neutrons leading to the final states up to [ital E][sub [ital x]]=15 MeV were measured. Spectroscopic information has been obtained from an analysis with the adiabatic deuteron breakup approximation, where [ital s]-wave deuteron breakup effects have been included. Proton unbound transitions were analyzed by means of Vincent and Fortune's method. It was found that the observed proton single-particle states in [sup 21,23]Na exhausted almost all the strength for the 2[ital s]1[ital d] shell. The distributions of the 2[ital s]1[ital d] strength were reasonably reproduced by recent 2[ital s]1[ital d] shell model calculations. The occupation probabilities and single-particle energies of the proton orbits near Fermi levels in the ground states of [sup 20,22]Ne were deduced in a framework of combined analysis of the stripping and pickup data on the same target nucleus.