Abstract
Excitation curves for the (ground state) reaction have been measured at observation angles of 15°, 45°, 70°, 90°, 110°, and 135° for proton energies between 0.8 and 3.0 Mev. These curves show pronounced resonance structure and strong interference effects between different levels. About 60 angular distributions and the total cross-section curve were constructed from the 6 differential cross-section curves. The angular distributions are peaked forward, except in the region near 1.6 Mev, where a broad resonance, interfering with nonresonant amplitudes, causes the angular distribution to become almost symmetric about 90°. The occurrence of forward peaking at all energies and the good agreement of the angular distribution at 2.84 Mev with a theoretical stripping curve suggest that a pickup process can account for a sizeable fraction of the reaction cross section, even at energies as low as 1 Mev. The total cross section indicates a resonance at 0.93 and weak maxima at 1.25, 1.65, and 2.3 Mev, but not at the level at 2.56 Mev. The differential cross section for the (ground state) reaction was measured at 90° from 0.8 to 3.0 Mev. In addition to the 0.93-Mev peak, this curve shows a pronounced minimum near 1.4 Mev and a weak anomaly at 2.56±0.02 Mev indicating a slight violation of the isotopic spin selection rule. An upper limit of 4× is obtained for the impurity of the , state at 8.89 Mev in .
- Received 27 August 1956
DOI:https://doi.org/10.1103/PhysRev.104.1307
©1956 American Physical Society