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HK: Hadronen und Kerne

HK 31: Nuclear Astrophysics II

HK 31.2: Vortrag

Dienstag, 17. März 1998, 14:15–14:30, G

Determination of the ³⁷Ar(n_th,α)³⁴S and ³⁷Ar(n_th,p)³⁷Cl cross sections — •Ronald Bieber¹, Cyriel Wagemans², Heinz Oberhummer³, Marc Loiselet⁴, Michel Gaelens⁴, Bruno Denecke¹, Jan Wagemans¹, and Peter Geltenbort⁵ — ¹Institute for Reference Materials and Measurements, Retieseweg, B-2440 Gent — ²Dept. of Subatomic and Radiation Physics, University of Gent, Proeftuinstraat 86, B-9000 Gent — ³T.U. Vienna, Austria — ⁴Universite Catholique de Louvain, Belgium — ⁵Institut Laue-Langevin, BP 156, F38042 Grenoble Cedex 9, France

³⁷Ar was produced at the cyclotron of the U.C.L. via the ³⁷Cl(p,n)³⁷Ar reaction. Several samples were prepared by implanting ³⁷Ar-ions in a thin aluminium foil, with a number of atoms varying between 10¹⁴ and 2×10¹⁵. These samples were used at a thermal neutron guide of the High Flux Reactor of the ILL (Grenoble) for the study of the ³⁷Ar(n_th,α)³⁴S and ³⁷Ar(n_th,p)³⁷Cl reactions. The charged particles emitted were detected with suited Si surface barrier detectors. The flux calibration was done using a well-defined ²³⁵U layer and relying on the ²³⁵U(n_th,f) reference cross-section. In this way we obtained a value of (1070±70)b for the ³⁷Ar(n_th,α) and (37±3)b for the ³⁷Ar(n_th,p) cross-section. These results are about two times smaller than the corresponding values reported by Asghar et al, Z. Phys. A288(1978)45.