Stellar (n,gamma) cross section of Ni-62

The Ni-62(n,gamma)Ni-63(t(1/2) = 100 +/- 2 yr) reaction plays an important role in the control of the flow path of the slow neutron-capture (s) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT = 25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the Ni-63 product nuclei. The experimental value of 28.4 +/- 2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of Ni-62 itself and the whole distribution of nuclei with 62 < A < 90 produced by the weak s process in massive stars.status: publishe