Stellar ( n,γ ) cross sections of Na23

Abstract

The cross section of the 23 Na(n, γ) 24 Na reaction has been measured via the activation method at the Karlsruhe 3.7 MV Van de Graaff accelerator. NaCl samples were exposed to quasistellar neutron spectra at kT = 5.1 and 25 keV produced via the 18 O(p, n) 18 F and 7 Li(p, n) 7 Be reactions, respectively. The derived capture cross sections σ kT=5keV = 9.1 ± 0.3 mb and σ kT=25keV = 2.03 ± 0.05 mb are significantly lower than reported in literature. These results were used to substantially revise the radiative width of the first 23 Na resonance and to establish an improved set of Maxwellian average cross sections. The implications of the lower capture cross section for current models of s-process nucleosynthesis are discussed.