Measurement of the stellar 58Ni( n,γ)59Ni cross section with accelerator mass spectrometry

The Ni-58(n,gamma)Ni-59 cross section was measured with a combination of the activation technique and accelerator mass spectrometry (AMS). The neutron activations were performed at the Karlsruhe 3.7 MV Van de Graaff accelerator using the quasistellar neutron spectrum at kT = 25 keV produced by the Li-7(p, n) Be-7 reaction. The subsequent AMS measurements were carried out at the 14 MV tandem accelerator of the Maier-Leibnitz Laboratory in Garching using the gas-filled analyzing magnet system (GAMS). Three individual samples were measured, yielding a Maxwellian-averaged cross section at kT = 30 keV of <sigma >(30 keV) = 30.4 (23)(syst)(9()stat) mbarn. This value is slightly lower than two recently published measurements using the time-of-flight (TOF) method, but agrees within the uncertainties. Our new results also resolve the large discrepancy between older TOF measurements and our previous value.