The elastic scattering of protons from carbon in the range of bombarding energies 1.5 to 5.5 Mev has been investigated, using protons from the Rice Institute Van de Graaff accelerator and a differentially pumped gas scattering chamber. Angular distributions and excitation curves at seven angles have allowed an explicit phase shift analysis of the data below 5 Mev. Only five nonzero phase shifts were necessary to fit the data to better than 10% at all energies and angles. The fourth and fifth excited states of ${\mathrm{N}}^{13}$ are identified at 4.808- and 5.37-Mev bombarding energy, and their respective assignments are $\frac{5}{2^{+}}$ and $\frac{3}{2^{+}}$, while their laboratory widths are 12 kev and 125 kev. The 4.43-Mev inelastic scattering $\gamma$ radiation was studied by obtaining excitation curves and angular distributions which confirmed the $\frac{3}{2^{+}}$ assignment for the 5.37-Mev resonance. The large ratio of inelastic to elastic reduced widths for this level suggests that it and, possibly, the fourth excited state of ${\mathrm{N}}^{13}$ are due to an $S$-wave proton configuration about ${\mathrm{C}}^{12}$ in its $2^{+}$ first excited state.

• Received 27 June 1956

DOI:https://doi.org/10.1103/PhysRev.104.143