${}^{62}$Ni($n,\gamma$) and ${}^{63}$Ni($n,\gamma$) cross sections measured at n_TOF/CERN

Abstract

The cross section of the ${}^{62}$Ni($n,\gamma$) reaction was measured with the time-of-flight technique at the neutron time-of-flight facility n_TOF at CERN. Capture kernels of 42 resonances were analyzed up to 200~keV neutron energy and Maxwellian averaged cross sections (MACS) from $kT=5-100$ keV were calculated. With a total uncertainty of 4.5%, the stellar cross section is in excellent agreement with the the KADoNiS compilation at $kT=30$ keV, while being systematically lower up to a factor of 1.6 at higher stellar temperatures. The cross section of the ${}^{63}$Ni($n,\gamma$) reaction was measured for the first time at n_TOF. We determined unresolved cross sections from 10 to 270 keV with a systematic uncertainty of 17%. These results provide fundamental constraints on $s$-process production of heavier species, especially the production of Cu in massive stars, which serve as the dominant source of Cu in the solar system.

References in corpus (1)

• Neutron capture cross section of unstable 63Ni: implications for stellar nucleosynthesis

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• The s process in massive stars, a benchmark for neutron capture reaction rates
• Experimental nuclear astrophysics in Italy
• Microscopic folding model analysis of the radiative $(n,\gamma )$ reactions near the $Z=28$ shell-closure and the weak s-process
• Stellar ${\beta }^{-}$-decay rate of ${}^{63}$Ni and its impact on the $s$-process nucleosynthesis in massive stars