Abstract
The differential cross section for elastic scattering of protons from has been measured to an accuracy of 7% for proton energies from 1.0 to 2.6 MeV at center-of-mass scattering angles of 39.2°, 54.7°. 90.0°, and 125.3°. Thin targets were prepared from methyl iodide enriched to 62% in and the scattered protons were analyzed using a double-focusing magnetic spectrometer. Proton groups corresponding to and were cleanly separated except for energies below 1.8 MeV at 39.2° and 54.7°. A theoretical curve calculated from a two-level formula was fitted to the data over the entire energy range. Seven resonances, all previously observed, were necessary to fit the data. The laboratory resonance energies (MeV), center-of-mass reduced widths (MeV cm×) and values assigned in this analysis are as follows: 1.150±0.002, 0.19, ; 1.366±0.050, 3.60, ; 1.461±0.003, 1.76, , 1.540±0.003, 0.09, ; 1.980±0.003, 0.45, (); 2.110±0.003, 1.66, ; 2.319±0.005, 0.09, . These resonance energies and reduced widths are in fair agreement with previous measurements. The spin and parity assignments for all levels, except those at , confirm previous experiments. The 1.540-MeV resonance had previously been assumed to have and the 1.980-MeV resonance had been assigned . Comparison of experiment and theory suggests the possibility of a broad resonance having in the vicinity of MeV.
- Received 1 December 1965
DOI:https://doi.org/10.1103/PhysRev.144.891
©1966 American Physical Society