| R. Terlizzi et al. (G. Aerts, S. Andriamonje, E. Berthoumieux, C. Carrapico, W. Dridi, F. Gunsing, C. Lampoudis, J. Pancin, L. Perrot, A. Plukis) |
The nuclear resonance parameters and the capture cross
section of the neutron magic isotope 139 La have been
measured relative to 197 Au in the energy range of 0.6
eV to 9 keV at the neutron time-of-flight (n TOF)
facility at CERN. We describe the experimental
apparatus and the data analysis procedures, which
concerned mainly the efficiency correction by means of
the pulse height weighting function technique and the
determination of different background components. We
extracted the resonance parameters and the main nuclear
quantities such as the resonance integral RI = 10.8 ±
1.0 b, the average γ widths for s and p waves ⟨ γ ⟩ l
=0 = 50.7 ± 5.4 meV and ⟨ γ ⟩ l =1 = 33.6 ± 6.9 meV,
the nuclear level densities ⟨D⟩l =0 = 252 ± 22 eV and
⟨D⟩l The nuclear resonance parameters and the capture
cross section of the neutron magic isotope 139 La have
been measured relative to 197 Au in the energy range of
0.6 eV to 9 keV at the neutron time-of-flight (n TOF)
facility at CERN. We describe the experimental
apparatus and the data analysis procedures, which
concerned mainly the efficiency correction by means of
the pulse height weighting function technique and the
determination of different background components. We
extracted the resonance parameters and the main nuclear
quantities such as the resonance integral RI = 10.8 ±
1.0 b, the average γ widths for s and p waves ⟨ γ ⟩ l
=0 = 50.7 ± 5.4 meV and ⟨ γ ⟩ l =1 = 33.6 ± 6.9 meV,
the nuclear level densities ⟨D⟩l =0 = 252 ± 22 eV and
⟨D⟩l =1 < 250 eV, and the neutron strength functions S0
= (0.82 ± 0.05) × 10− 4 and S1 = (0.55 ± 0.04) × 10− 4
. These results represent a significant improvement over
previous data. The deduced Maxwellian-averaged capture
cross sections are important for the interpretation of
the most recent spectroscopic observations in
low-metallicity stars. |
