Accelerator mass spectrometry measurement of the reaction Cl 35 (n,γ) Cl 36 at keV energies

The nuclide Cl35 can act as a minor "neutron poison" in the stellar slow neutron capture process. Neutron activation combined with accelerator mass spectrometry (AMS) was applied to measure the (n,γ) cross section of Cl35 for neutron spectra simulating Maxwell-Boltzmann distributions of kT≈30 and 40 keV. The neutron activations were performed at the Karlsruhe Van de Graaff accelerator and at the superconducting linear accelerator of the Soreq Applied Research Accelerator Facility utilizing the Li7(p,n)Be7 reaction. AMS measurements of the irradiated samples were performed at the 3 MV Vienna Environmental Research Accelerator, the 6 MV tandem accelerator at the Dresden AMS facility, and the 14 UD tandem accelerator of the Australian National University in Canberra. Our method is independent of previous measurements. For an energy of kT=30keV, we report a Maxwellian averaged cross section of 8.33(32) mb. Using this new value in stellar isotopic abundance calculations, minor changes for the abundances of Cl35, Cl36, and S36 are derived.