München 2006 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 19: Kern- und Teilchen-Astrophysik
HK 19.4: Vortrag
Dienstag, 21. März 2006, 15:00–15:15, E
Neutron capture rates on neutron-rich Argon isotopes measured in inverse kinematics — •A.N. Ostrowski1, L. Godefroy2, O. Sorlin2, Y. Blumenfeld2, and K.-L. Kratz3 — 1Fakultät für Physik und Astronomie, Universität Heidelberg, D-69120 Heidelberg, Germany — 2Institut de Physique Nucléaire, F-91406 Orsay Cedex, France — 3Institut für Kernchemie, Universität Mainz, D-55099 Mainz, Germany
In order to evaluate the influence of the N=28 closed shell on astrophysical neutron capture rates and to determine the size of the N=28 shell gap a series of transfer reactions in inverse kinematics using radioactive 44,46Ar-beams and deuterated polythene targets have been performed at the SPIRAL accelerator complex at the GANIL facility.
In the astrophysical context this experiment will enable us to understand the large 48Ca/46Ca abundence ratio of up to 250 found in refractory meteoritic inclusions, e.g. the EK 1-4-1 sample from the Allende meteorite. 46Ar is thought to be the main progenitor of the 46Ca and the determination of its neutron capture cross section provides a constraint on the neutron densities present in explosive stellar environments to account for the large isotopic ratio found.
In addition, neither the size of the N=28 shell gap nor the occupation of the orbitals involved have been determined experimentally in any of the abovementioned Argon nuclei so far. The result therefore opens a window on either the erosion or the persistence of the N=28 shall gap. The experiments performed and their results will be discussed.