Münster 2011 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 25: Nukleare Astrophysik II

HK 25.7: Vortrag

Dienstag, 22. März 2011, 18:15–18:30, HS3

59Fe(n,γ)60Fe measured by Coulomb Dissociation — •Tanja Heftrich — University of Frankfurt, Germany

One of the fundamental signatures for active nucleosynthesis in our galaxy is the observation of long-lived radioactive elements using γ-ray observatories such as INTEGRAL. Of particular importance are the two long-lived radioactive isotopes ²⁶Al and ⁶⁰Fe whose production is thought to be associated with the nucleosynthesis in hot carbon or oxygen shell burning in massive pre-supernova stars and in the subsequent shockfront driven explosive nucleosynthesis of type II supernovae. While the reactions of ²⁶Al has been studied extensively, very little is known about the reactions associated with the nucleosynthesis of ⁶⁰Fe. The production rate ⁵⁹Fe(n,γ)⁶⁰Fe is difficult to measure directly because of the short half-life of ⁵⁹Fe (t_1/2=44.5 d). Coulomb dissociation measurements of ⁵⁹Fe and ⁶⁰Fe were performed at the R3B/LAND Setup at GSI. The unstable iron isotopes were produced by fragmentation of a 660 AMeV primary beam of ⁶⁴Ni on a 4 g/cm2 Be target. The dissociation cross section ⁶⁰Fe(γ, n)⁵⁹Fe is important to study the inverse neutron capture process via detailed balance. In order to prove this method, ⁵⁹Fe(γ, n)⁵⁸Fe was studied to determine the already directly measured ⁵⁸Fe(n,γ)⁵⁹Fe cross section. The astrophysical motivation, an overview of the experimental setup and first results of the measurements will be presented. This project is supported by the HGF Young Investigator Project VH-NG-327.