Elastic Scattering of 1- to 2.7-MeV Protons byC14

The differential elastic scattering cross section for protons scattered by ${\mathrm{C}}^{14}$ was measured for energies from 1.0 to 2.7 MeV at center-of-mass scattering angles of 39.2°, 54.7°, 90°, 125.3°, and 161.4°. Thin self-supporting carbon foils enriched to 10% ${\mathrm{C}}^{14}$ were used as targets. Outgoing protons were analyzed with a 180° double-focusing magnetic spectrometer at the lower angles, while a solid-state detector was used at 161.4°. The experimental data were fitted using a theoretical expression derived from $R$-matrix theory and accurate in the "two-level" approximation. Anomalies corresponding to ${\mathrm{N}}^{15}$ levels at 11.293, 11.416, 11.582, 12.093, 12.144, and 12.524 MeV were observed. Best-fit parameters (center-of-mass proton partial width in keV, center-of-mass total width in keV, and $J^{\pi }$) for these anomalies in the order listed are: 5.6, 7.9, ${\mathrm{½}}^{-}$; 11.0, 34.0, ${\mathrm{½}}^{+}$; 415.0, 418.0, ${\mathrm{½}}^{+}$; 1.7, 14.0, ${\frac{5}{2}}^{+}$; 16.6, 47.0, ${\frac{3}{2}}^{-}$; 80.0, 80.0, ${\frac{5}{2}}^{+}$. Although these widths are lower than those previously reported, they are in essential agreement with published data. Uncertainty concerning certain previous $J^{\pi }$ assignments has been removed.