Measurement of ¹³⁹La(n, γ) cross section

We measured the neutron capture cross section of La-139 relative to Au-197 in the energy range of 0.6 cV to 9 keV at n_TOF, the neutron time-of-flight facility at CERN. After a description of the experimental apparatus, we discuss data analysis procedures. The data were fitted using R-matrix formalism to extract resonance parameters which, in turn, were used to calculate average level spacings D-0 = 268 +/- 22 eV and D-1 > 250 cV, and neutron strength functions S-0 = (0.79 +/- 0.03)x 10(-4) and S-1 = (0.73 +/- 0.05)x 10(4) for s- and p-wave resonances. The data also were used to determine Maxwellian-averaged neutron capture cross sections which, in turn, were used to calculate the La-139 abundance synthesized in a stellar model of the main component of the s process