Production and isobaric separation of 63Ni ions for determination of the 62Ni(n,γ)63Ni reaction cross section at stellar temperatures

Half-life ofTi44

The half-life of $^{44}\mathrm{Ti}$ has been measured to be ${T}_{\frac{1}{2}}=54.2\ifmmode\pm\else\textpm\fi{}2.1$ yr, somewhat higher than previously published values of 46.4\ifmmode\pm\else\textpm\fi{}1.7 and 48.2\ifmmode\pm\else\textpm\fi{}0.9 yr. The present value was obtained from the specific activity and the radioisotope concentration of several Ti${\mathrm{O}}_{2}$ samples, each spiked with a $^{44}\mathrm{Ti}$ activity of about 1.2 \ensuremath{\mu}Ci. The specific activity was measured via the 1157 keV $\ensuremath{\gamma}$ line from the decay of the $^{44}\mathrm{Sc}$ daughter. $^{44}\mathrm{Ti}$/Ti concentrations were measured with the Argonne FN tandem accelerator in conjunctio…

Stellar(n,γ)Cross Section ofNi62

The 62Ni(n,gamma)63Ni(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 63Ni product nuclei. The experimental value of 28.4+/-2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of 62Ni itself and the whole distribution of nuclei with 62<A<90 produced by the weak s process in massive stars.