Measurement of La-139(n, gamma) 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

Measurement of ¹³⁹La(n,γ) cross section at n_TOF

The capture cross section of the 139La has been measured relative to 197Au standard at n_TOF. We provide here a short description of the experimental apparatus and of the data analysis procedures. The extracted resonance parameters allow to calculate the fundamental nuclear quantities such as average spacing > D D 250 eV neutron strength functions S0 = (0.79 +/- 0.03)x 10(4), and S1 = (0.73 +/- 0.05)x10-4 and the Maxwellian-averaged capture cross section (MACS). The MACS is particularly useful for the determination of the abundance synthesized by the main component of the s process [3]