Total Neutron Cross Section of Sodium

The total neutron cross section of sodium has been measured over the energy range 120 to 1000 kev using resolutions of 2.5 to 5 kev. A number of resonances, corresponding to excited states in the compound nucleus ${\mathrm{Na}}^{24}$ were investigated. In some cases it is possible to assign $J$ and $l$ values and to compute the effective level spacings ${D_J}^l$. Evidence is given to show that the ${D_J}^l$, which are a measure of the complexity of a state, differ by a factor of 8 for two states of the same type and at approximately the same excitation energy (7.5 Mev) in the ${\mathrm{Na}}^{24}$ nucleus. An anomalous $S$-wave resonance at 300 kev suggests that the potential scattering may be spin dependent.