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HK: Hadronen und Kerne

HK 50: Nukleare Astrophysik III

HK 50.4: Vortrag

Mittwoch, 26. März 1997, 18:00–18:15, HS D

In-beam Coulomb excitation of ¹⁸⁰Ta^m and its relevance for s-process production^⋆ — •C. Schlegel¹, J. de Boer², J. Gerl³, M. Loewe², P.J. Napiorkowski⁴, P. von Neumann-Cosel¹, A. Richter¹, J. Srebrny⁵, and H.J. Wollersheim³ — ¹Institut f"ur Kernphysik, TH-Darmstadt, D-64289 Darmstadt — ²Sektion Physik, Universit"at M"unchen, D-85748 Garching — ³GSI, D-64291 Darmstadt — ⁴Heavy Ion Laboratory, Warsaw University, Poland — ⁵Nuclear Physics Division, Warsaw University, Poland

A central question concerning the nucleosynthesis of ¹⁸⁰Ta is whether s-process production can be ruled out due to the presence of intermediate levels at sufficently low excitation energy allowing for a depopulation of the stable K^π = 9⁻ isomer in the stellar photon bath. Here we report on an in-beam Coulomb excitation measurement using a E = 4 MeV/ u ¹³⁶Xe beam impinging on a ¹⁸⁰Ta target enriched from the natural abundance of 0.012% to 5.6%. Scattered particles were measured with a set of PPAC under forward angles 15^∘ − 95^∘. Coincidence photons were detected with a set of five EUROBALL cluster modules and with the Darmstadt-Heidelberg ’Crystal Ball’ covering the full solid angle. Excitations in ¹⁸⁰Ta are identified by comparison to results obtained with a natural Ta target containing 99.99% ¹⁸¹Ta. First results are presented.
Work supported by BMBF contract 06DA665I, DFG contract Bo 1109/1 and the Volkswagen Foundation