Differential Cross Section Measurements for the Elastic Scattering of Protons byN14

The differential cross section for the elastic scattering of protons by ${\mathrm{N}}^{14}$ has been measured in the energy range from 1.5 to 3.5 Mev at scattering angles of 39°14′, 54°44′, 90°, 125°16′, and 140°46′ in the center-of-mass coordinate system. The probable error in the values of the cross section is about 4 to 5%. Pronounced anomalies in the cross section occur at laboratory proton energies of 1.55, 1.74, 1.805, 2.36, 2.49, 3.20, and 3.40 Mev, with a probable error in these energies of 0.01 Mev. The anomaly at 3.40 Mev indicates a previously unreported level in ${\mathrm{O}}^{15*}$ at about 10.5 Mev. The magnitude of the off-resonance cross section at 140°46′ is about four times, at 125°16′ about three times, and at 90° about two times that which would result from pure Rutherford scattering. At 54°44′ the off-resonance cross section differs from the Rutherford cross section over most of the energy range by less than 5%, while at 39°14′ the cross section is generally 10 to 20% below the Rutherford cross section.