Results are reported of high resolution transmission measurements on Teflon, ${\left(\mathrm{C}{\mathrm{F}}_2\right)}_n$, for the total cross section of natural fluorine vs energy from 500 eV to 200 keV. This region has three strong $l=1\mathrm{}$ levels which were fitted using a multilevel $R$-matrix analysis. The best fit ($E_0,J,{\Gamma }_n$) parameters are (26.99, 2, 0.325), (48.78, 1, 1.67), and (97.50, 1, 14.5), where $E_0$ and ${\Gamma }_n$ are in keV. The results are consistent with previous measurements. They yield $10{}_{}{}^4{}_{}{}^{}S_1^{}{}_{}{}^{}=\left({11.1}_{-5.2\mathrm{}}^{+12.4\mathrm{}}\right)$ for ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}$ using a 5 fm channel redius.

NUCLEAR REACTIONS ${}_{}{}^{19}{}_{}{}^{}\mathrm{F}\mathrm{}(n,n)\mathrm{}$, $n,\gamma$, $E=500\mathrm{} \mathrm{eV}-200 \mathrm{keV}$; measured ${\sigma }_t\mathrm{}\left(E\right)\mathrm{}$; deduced $E_0$, $l$, $J$, ${\Gamma }_n$, $S_1$.

• Received 15 August 1974

DOI:https://doi.org/10.1103/PhysRevC.10.2147