Solving the stellar 62Ni problem with AMS
| Autor: | S. Walter, F. Käppeler, R. Schwengner, Andreas Wagner, M. Poutivtsev, J. Lachner, Georg Rugel, Arnd R. Junghans, Moumita Maiti, Iris Dillmann, T. Faestermann, C. Nair, M. Erhard, Gunther Korschinek |
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| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Předmět: |
Physics
Nuclear and High Energy Physics Isotope FOS: Physical sciences nucleosynthesis neutron capture branching supernova photoactivation accelerator masse spectrometry Branching points Tandem accelerator Nuclear physics Neutron capture Cross section (physics) Astrophysics - Solar and Stellar Astrophysics Nuclear Experiment (nucl-ex) s-process Astrophysics - Instrumentation and Methods for Astrophysics Instrumentation and Methods for Astrophysics (astro-ph.IM) Instrumentation Nuclear Experiment Solar and Stellar Astrophysics (astro-ph.SR) Accelerator mass spectrometry |
| Zdroj: | Nuclear Instruments and Methods in Physics Research B 268(2010), 1283 AMS-11-THE 11th International Conference on Accelerator Mass Spectrometry, 14.-19.09.2008, Roma, ItalyNuclear Instruments and Methods in Physics Resarch B: Elsevier |
| Popis: | An accurate knowledge of the neutron capture cross sections of 62,63Ni is crucial since both isotopes take key positions which affect the whole reaction flow in the weak s process up to A=90. No experimental value for the 63Ni(n,gamma) cross section exists so far, and until recently the experimental values for 62Ni(n,gamma) at stellar temperatures (kT=30 keV) ranged between 12 and 37 mb. This latter discrepancy could now be solved by two activations with following AMS using the GAMS setup at the Munich tandem accelerator which are also in perfect agreement with a recent time-of-flight measurement. The resulting (preliminary) Maxwellian cross section at kT=30 keV was determined to be 30keV = 23.4 +/- 4.6 mb. Additionally, we have measured the 64Ni(gamma,n)63Ni cross section close to threshold. Photoactivations at 13.5 MeV, 11.4 MeV and 10.3 MeV were carried out with the ELBE accelerator at Forschungszentrum Dresden-Rossendorf. A first AMS measurement of the sample activated at 13.5 MeV revealed a cross section smaller by more than a factor of 2 compared to NON-SMOKER predictions. Comment: Proceedings of the 11th International Conference on Accelerator Mass Spectrometry in Rome, Sept. 14-19, 2008; to be published in Nucl. Instr. Meth. A |
| Databáze: | OpenAIRE |
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