Parts | Days | Selection | Search | Downloads | Help
HK: Fachverband Hadronen und Kerne
HK 28: Nuclear Astrophysics
HK 28.2: Group Report
Tuesday, March 17, 2009, 14:30–15:00, H-ZO 60
Photon strength functions and cosmic nucleosynthesis. — •Chithra Nair1, Arnd R. Junghans1, Martin Erhard1, Roland Beyer1, Klaus D. Schilling1, Ronald Schwengner1, Andreas Wagner1, and Eckart Grosse1,2 — 1Institut für Strahlenphysik, Forschungszentrum Dresden-Rossendorf, Germany — 2Institut für Kern- und Teilchenphysik, Technische Universität Dresden, Germany
In network calculations for the cosmic nucleosynthesis the electromagnetic dissociation occurring in hot environments strongly depends on the low energy tail of the photon strength function peaking in the isovector giant dipole resonance (GDR). The widely used procedure of adjusting a single Lorentzian to the (gamma,n) cross section in the GDR maximum is clearly inadequate in various cases. Photo-dissociation studies of the p-rich nuclei 92Mo and 144Sm into several different exit channels show that competing processes are surprisingly strong, in particular in the tail region. Strength functions derived from a systematic study of many nuclei with A>80 were used in Hauser-Feshbach calculations performed with the code TALYS. They render a consistent description of the GDR for (gamma,n) and for the other observed channels. This study is based on droplet model results for the GDR-energy and on hydrodynamic considerations about its width as well as on nuclear shape parameters. For nuclei with A>80 these are sufficiently well known from nuclear structure studies resulting in a reliable prediction of photon strength functions also for deformed nuclei which can be used in calculations for the cosmic nucleosynthesis.