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Elastic Scattering of 1- to 2.7-MeV Protons by C 14

1968; American Institute of Physics; Volume: 171; Issue: 4 Linguagem: Inglês

10.1103/physrev.171.1230

1536-6065

W. R. Harris, Jerawan Armstrong,

X-ray Spectroscopy and Fluorescence Analysis

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\ifmmode^\circ\else\textdegree\fi{}, 54.7\ifmmode^\circ\else\textdegree\fi{}, 90\ifmmode^\circ\else\textdegree\fi{}, 125.3\ifmmode^\circ\else\textdegree\fi{}, and 161.4\ifmmode^\circ\else\textdegree\fi{}. Thin self-supporting carbon foils enriched to 10% ${\mathrm{C}}^{14}$ were used as targets. Outgoing protons were analyzed with a 180\ifmmode^\circ\else\textdegree\fi{} double-focusing magnetic spectrometer at the lower angles, while a solid-state detector was used at 161.4\ifmmode^\circ\else\textdegree\fi{}. 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 ${J}^{\ensuremath{\pi}}$) for these anomalies in the order listed are: 5.6, 7.9, ${\mathrm{\textonehalf{}}}^{\ensuremath{-}}$; 11.0, 34.0, ${\mathrm{\textonehalf{}}}^{+}$; 415.0, 418.0, ${\mathrm{\textonehalf{}}}^{+}$; 1.7, 14.0, ${\frac{5}{2}}^{+}$; 16.6, 47.0, ${\frac{3}{2}}^{\ensuremath{-}}$; 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 ${J}^{\ensuremath{\pi}}$ assignments has been removed.