Darmstadt 2008 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 36: Kern- und Teilchen-Astrophysik
HK 36.8: Vortrag
Donnerstag, 13. März 2008, 18:45–19:00, 2B
Parity Dependent Nuclear Level Densities in Hauser-Feshbach Calculations for Stellar Reaction Rates — •Hans Peter Loens1, Gabriel Martínez-Pinedo1, Karlheinz Langanke1, Friedrich-Karl Thielemann2, and Thomas Rauscher2 — 1Gesellschaft für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt, Germany — 2Universiät Basel, Klingelbergstrasse 82, 4056 Basel, Switzerland
The statistical Hauser-Feshbach model is used to obtain reaction rates that are being used in nucleosynthesis simulations. The necessary nuclear level densities (NLD) have been calculated with equipartioned parities. However, newer theoretical calculations [1-4] and as well as experimental investigations [4] show that the assumption of equipartitioned parities within the NLD is not generally true up to rather high energies.
We calculated (n,γ)-reaction-rates - that are necessary for r-process modelling - with a parity dependent level density and developed a simple model to introduce a parity dependence for the compound nucleus. Our investigations clearly show that the new treatments can have an influence on the reaction rate itself. Moreover, we studied the combination of our new parity treatment with microscopical results (pygmy resonances) of γ-strengths for certain nuclei.
[1] H. Nakada and Y. Alhassid in Phys. Rev. Lett. 79, 2939 (1997)
[2] S. Hilaire and S. Goriely in Nucl. Phys. A 776, 63-81 (2006)
[3] D. Mocelj et al.in Phys. Rev. C 75, 045805 (2007)
[4] Y. Kalmykov et al. in Phys. Rev. Lett. 99, 202502 (2007)