s-process nucleosynthesis in massive stars: new results on {sup 60}Fe, {sup 62}Ni and {sup 64}Ni
- Gesellschaft fuer Schwerionenforschung, 64291 Darmstadt (Germany)
- Forschungszentrum Karlsruhe, Institut fuer Kernphysik, 76021 Karlsruhe (Germany)
- Physik Department, TU Muenchen, 85748 Garching (Germany)
- Physikalisch-Technische Bundesanstalt, 38116 Braunschweig (Germany)
- University of Notre Dame, Department of Physics, Notre Dame, IN 46556 (United States)
- Laboratory for Environmental and Radiochemistry, PSI (Switzerland)
The s process synthesizes the elements between Fe and Sr in massive stars during two major evolutionary stages, convective core He burning and C shell burning. This scenario implies fascinating consequences for the chemical evolution of the star. For instance, the neutron capture rate at each isotope can have a big influence on the production of many of the subsequent higher mass isotopes. Correspondingly, one needs to know the (n,{gamma}) cross sections of the involved isotopes with high accuracy in order to determine the abundance pattern reliably and to obtain a consistent picture of this stage. This contribution gives an overview on recent and future experiments for the Fe/Ni nucleosynthesis in massive stars. New results on {sup 60}Fe, {sup 62}Ni and {sup 64}Ni are reported. {sup 60}Fe is mostly produced during the short convective C shell burning phase, where peak densities of {approx}10{sup 11} cm{sup -3} are reached, prior to the SN explosion. The stellar (n,{gamma}) cross section of {sup 60}Fe could be measured with a 1 {mu}g sample obtained at PSI (Switzerland), which was sufficient for an activation measurement using the intense, quasi-stellar neutron field for a thermal energy of 25 keV at the Karlsruhe Van de Graaff accelerator. The FZK accelerator was also used for an activation of {sup 62}Ni, whereas in this case, the number of {sup 63}Ni nuclei produced were determined via accelerator mass spectroscopy at the Maier-Leibnitz-Laboratorium in Garching/Munich. The (n,{gamma}) cross section of {sup 64}Ni at a stellar temperature equivalent to 50 keV has been measured in a collaboration between FZK Karlsruhe and PTB Braunschweig. Finally, complementary time of flight measurements on the Fe and Ni isotopes over a broad energy range are planned at the white neutron source n lowbar TOF of CERN for the future campaign in 2009.
- OSTI ID:
- 21255414
- Journal Information:
- AIP Conference Proceedings, Vol. 1090, Issue 1; Conference: 13. international symposium on capture gamma-ray spectroscopy and related topics, Cologne (Germany), 25-29 Aug 2008; Other Information: DOI: 10.1063/1.3087019; (c) 2009 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Determination of the stellar (n,{gamma}) cross section of {sup 40}Ca with accelerator mass spectrometry
Ni elemental neutron induced reaction cross-section evaluation