Neutron capture measurements of the noble gas isotopes 22Ne, 40Ar and 78,80,84,86Kr in the keV energy region Original Research Article

At the Karlsruhe and Tübingen 3.75 MV Van de Graaff accelerators the cross sections of 22Ne(n,γ)23Ne (37.2 s), 40Ar(n,γ)41Ar (1.83 h), and the Kr isotopes 78Kr(n,γ)79Krm (50 s), 78Kr(n,γ)79Kr (35.04 h), 80Kr(n,γ)81Krm (13.1 s), 84Kr(n,γ)85Krm (4.48 h), and 86Kr(n,γ)87Kr (76.3 m), were measured in the keV energy range by the regular and/or the fast cyclic activation techniques via the characteristic γ-ray lines in the decay of the respective residual nuclei. High pressure gas samples which consisted of 22Ne–Kr and 40Ar–Kr mixtures were irradiated using the 7Li(p,n) and T(p,n) reactions. The measurements were carried out at the neutron energies 25, 30, 52, 104, 149, 180, and 215 keV. Stellar reaction rates for thermal energies kT between 1 and 250 keV were determined. The population probability of the 85Krm isomeric state by neutron capture of 84Kr was studied as a function of neutron energy. No significant energy dependence was found.