Nuclear astrophysics with real photons

Majority of the light elements up to iron are formed by successive rounds of thermonuclear fusion burning in the stellar interiors. The nuclei heavier than iron (Z>26) are being synthesized mainly by neutron-capture reactions – the astrophysical r-and s-processes. But the 35 neutron deficient stable isotopes between Se and Hg, the so-called p-nuclei, are shielded from the rapid neutron capture by stable isobars [1]. The possible site for the formation of p-nuclei are astrophysical scenarios like supernova explosions and their production mechanism is understood as chains of photodisintegrations of the type (γ, n), (γ, p) or (γ, α) on heavy seed nuclei. The natural abundances of the p-nuclei are in the order of 0.01 – 1%. For the network calculations that yield the p-nuclei abundances, precise values of the relevant astrophysical reaction rates are necessary. The data used presently for p-process nucleosynthesis modelling are mainly based on theoretical cross sections obtained from Hauser-Feshbach statistical model calculations. In this context, the knowledge of the experimental cross sections of the p-nuclei is of crucial importance. We are focussing on the photo-dissociation studies of various medium-mass nuclei and our aim is to get more accurate experimental cross sections which will surely be able to improve the present astrophysical network calculations. To study the p-nuclei by the method of bremsstrahlung induced activation, the superconducting electron accelerator ELBE delivers beams up to 40 MeV energy with average currents up to 1mA. An overview on the experimental facilities for nuclear physics at the superconducting electron accelerator ELBE of Forschungszentrum Dresden-Rossendorf, Germany will be given . In particular, the photodissociation studies on the p-nuclei 92Mo and 144Sm will be discussed.