Düsseldorf 2007 – wissenschaftliches Programm

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MS: Fachverband Massenspektrometrie

MS 4: Neue Trends und Anwendungen in der AMS

MS 4.5: Vortrag

Dienstag, 20. März 2007, 17:30–17:45, 5F

The supernova-nucleosynthesis ⁴⁰Ca(α,γ)⁴⁴Ti reaction — Pankaj Baghel³, Thomas Faestermann¹, Klaus Knie¹, Moumita Maiti¹, Astrid Meier¹, •Hisham Nassar^1,2, Gunther Korschinek¹, Michael Paul², Mikhail Poutivtsev¹, and Georg Rugel¹ — ¹Technische Universität München, Fakultät für Physik — ²Hebrew University of Jerusalem, Israel — ³Nuclear Science Center, New Delhi, India

The ⁴⁴Ti (t_1/2=59y) nuclide is considered an important signature of core-collapse supernova (SN) nucleosynthesis and has recently been observed as live radioactivity by γ-ray astronomy from the Cas A SN remnant. We investigated in the laboratory the major ⁴⁴Ti production reaction, ⁴⁰Ca(α,γ)⁴⁴Ti (E_cm=0.6-1.2 MeV/u) by off-line counting of ⁴⁴Ti nuclei using accelerator mass spectrometry. The observed yield is significantly higher than inferred from other experiments. The derived astrophysical rate of this reaction is a factor 5-10 higher than calculated in current models. The yields calculated by multi-dimensional SN explosion calculations proposed to explain the observed ⁴⁴Ti yield of Cas A, in which parts of deeper layers can be ejected while some of the outer layers fall back, are expected to be enhanced in ⁴⁴Ti as well. The nucleosynthesis ⁴⁰Ca(α,γ)⁴⁴Ti reaction will be studied also using the MP tandem accelator in the Technical University of Munich (TUM). In this experiment, the reaction will be performed in finer steps to determine high productive energy regions in the relevant astrophysical energy regime. Preliminary results will be presented. In addition, a comparison of the different measurements in different laboratories will be discussed.