The stellar (n,gamma) cross section of 62Ni

The 62Ni(n,gamma)63Ni(t_1/2=100+-2 yrs) reaction plays an important role in nucleosynthesis by controlling the flow path of the slow neutron capture (s-) process. We have determined 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 a new technique of fast-neutron activation in which accelerator mass spectrometry (AMS) is applied to detect the 63Ni product nuclei. The experimental value of 22.6+-2.4 mb differs significantly from predicted values and affects the whole distribution of nuclei with A=60-90 produced by the weak s-process in massive stars