Direct neutron capture cross sections of 62Ni in the s-process energy range

Direct neutron capture on 62Ni is calculated in the DWBA and the cross sections in the energy range relevant for s-process nucleosynthesis are given. It is confirmed that the thermal value of the capture cross section contains a subthreshold resonance contribution. Contrary to previous investigations it is found that the capture at higher energies is dominated by p-waves, thus leading to a considerably increased cross section at s-process energies and a modified energy dependence.Comment: 10 pages, 1 figure, corrected typos in Eq. 6 and subsequent paragrap

Thermonuclear Reaction Rate of 23Mg(p,gamma)24$Al

Updated stellar rates for the reaction 23Mg(p,gamma)24Al are calculated by using all available experimental information on 24Al excitation energies. Proton and gamma-ray partial widths for astrophysically important resonances are derived from shell model calculations. Correspondences of experimentally observed 24Al levels with shell model states are based on application of the isobaric multiplet mass equation. Our new rates suggest that the 23Mg(p,gamma)24Al reaction influences the nucleosynthesis in the mass A>20 region during thermonuclear runaways on massive white dwarfs.Comment: 13 pages (uses Revtex) including 3 postscript figures (uses epsfig.sty), accepted for publication in Phys. Rev.

The importance of nuclear masses in the astrophysical rp-process

The importance of mass measurements for astrophysical capture processes in general, and for the rp-process in X-ray bursts in particular is discussed. A review of the current uncertainties in the effective lifetimes of the major waiting points 64Ge, 68Se, and 72Kr demonstrates that despite of recent measurements uncertainties are still significant. It is found that mass measurements with an accuracy of the order of 10 keV or better are desirable, and that reaction rate uncertainties play a critical role as well.Comment: 14 pages, 4 figures, to appear in International Journal of Mass Spectroscop

Thermonuclear reaction rate of 23 Mg ( p , γ ) 24 Al

Updated stellar rates for the reaction 23Mg(p,g )24Al are calculated by using all available experimental information on 24Al excitation energies. Proton and g -ray partial widths for astrophysically important resonances are derived from shell-model calculations. Correspondences of experimentally observed 24Al levels with shell-model states are based on application of the isobaric multiplet mass equation. Our new rates suggest that the 23Mg(p,g )24Al reaction influences the nucleosynthesis in the mass A.20 region during thermonuclear runaways on massive white dwarfs