Neutron Resonance Spectroscopy. XIII. Na to 320 keV

Results are presented of measurements of the total cross section vs energy which was measured to 320 keV for pure metallic sodium. $R$-matrix fits were made to the seven prominent observed resonances. The best-fit parameters for ($E_0,\Gamma ,J,l$) for each resonance are: (2.850, 0.400, 1, 0); (53.15, 1.08, 2, 1); (199.0, 4.5, 1, 0); (212.5, 15, 0, 1); (238, 3.9, 2, 1); (242, 3.5, 0, 1); (297, 1.8, 2, 0), where $E_0$ and $\Gamma$ are in keV. Three levels are assigned to be $s$ levels, and four to be $p$ levels. This gives ${10}^4{S}_0=0.24\left(1_{-0.58\mathrm{}}^{+1.91\mathrm{}}\right)$ and ${10}^4{S}_1=2.06\left(1_{-0.39\mathrm{}}^{+0.77\mathrm{}}\right)$. The $S_1$ evaluation includes the presence of weak $p$ levels seen in capture measurements by others.