Theoretical Neutron-Capture Cross Sections for r-Process Nucleosynthesis
In The 48Ca Region
T. Rauscher, W. Boehmer, K.-L. Kratz, W. Balogh, H. Oberhummer;
Proc. Int. Conf. on Exotic Nuclei and Atomic Masses "ENAM 95", eds.
M. de Saint Simon and O. Sorlin (Editions Frontières, Gif-sur-Yvette 1995), p
p. 683.

Abstract:
We calculate neutron capture cross sections for r-process
nucleosynthesis in the $^{48}$Ca region, namely for the isotopes
$^{40-44}$S, $^{46-50}$Ar, $^{56-66}$Ti, $^{62-68}$Cr, and $^{72-76}$Fe.
While previously only cross sections resulting from the compound nucleus
reaction mechanism (Hauser-Feshbach) have been considered, we recalculate
not only that contribution to the cross section but also include direct
capture on even-even nuclei. The level schemes, which are of utmost
importance in the direct capture calculations, are taken from quasi-particle
states obtained with a folded-Yukawa potential and Lipkin-Nogami pairing.
Most recent deformation values derived from experimental data on $\beta$-decay
half lives are used where available.
Due to the consideration of direct capture, the capture rates are enhanced
and the turning points'' in the r-process path are shifted to slightly
higher mass numbers. We also discuss the sensitivity of the direct capture
cross sections on the assumed deformation.

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