Stellar neutron capture cross sections of Ne20,21,22

The stellar (n,γ) cross sections of the Ne isotopes are important for a number of astrophysical quests, i.e., for the interpretation of abundance patterns in presolar material or with respect to the s-process neutron balance in red giant stars. This paper presents resonance studies of experimental data in the keV range, which had not been fully analyzed before. The analyses were carried out with the R-matrix code sammy. With these results for the resonant part and by adding the components due to direct radiative capture, improved Maxwellian-averaged cross sections (MACS) could be determined. At kT=30keV thermal energy we obtain MACS values of 240±29,1263±160, and 53.2±2.7 μbarn for Ne20,Ne21, and Ne22, respectively. In earlier work the stellar rates of Ne20 and Ne21 had been grossly overestimated. Ne22 and Ne20 are significant neutron poisons for the s process in stars because their very small MACS values are compensated by their large abundances.