Multilevel resonance analysis of the total neutron cross-section of 23Na and Ca below 1 MeV

The total neutron cross-sections of 23Na and Ca have been analysed below 1 MeV in order to provide neutron resonance parameters. The analysis uses the standard multilevel R-matrix formulas for a single open channel. A chi-squared fitting procedure is used for shape analysis. Resonance widths and energies have been assigned for 23Na up to 900 keV. The values of l and J have been determined up to 439 keV; above this energy the inelastic channel opens and the assigned J values are only lower limits. In the case of Ca, the parameters of resonances between 0.5 and 1.2 MeV have been determined. In many cases we have used new differential data for Ca to verify the l-value obtained by fitting the resonance. The channel radii and s and p-wave strength function of these nuclei are also discussed. (author)