The differential cross sections for the ground-state proton group from the ${\mathrm{C}}^{12}(t, p){\mathrm{C}}^{14}$ reactions, and for the ground-state and first-excited-state alpha-particle groups from the ${\mathrm{C}}^{12}(t, \alpha ){\mathrm{B}}^{11}$ reactions, have been studied as functions of the angle of emission and the bombarding energy in the region from 0.800 to 2.025 Mev. The elastically scattered tritons have also been studied in the energy region from 1.000 to 1.950 Mev. The angular distributions of all reaction groups are complex. The basic structure of the angular distributions for the ground-state alpha-particle group is retained throughout the energy region studied; however, it shifts toward higher angles with increasing bombarding energy. The structures of the angular distributions for the first-excited-state alpha-particle group and the ground-state proton group shift smoothly toward lower angles with increasing energy. The first-excited-state alpha-particle group exhibits a resonance at 1.13 Mev at which the total cross section increases by a factor of 4. The width of this resonance is about 50 kev. The angular distributions of this group are not affected by the resonance, and the effects of this resonance are negligible in the other reaction channels. The total cross sections for all of the reaction groups increase rapidly between 1.5 and 1.7 Mev. This increase to some extent may be due to a broad anomaly in the region of 1.8 Mev. The total cross sections for the ground-state and first-excited-state alpha-particle groups at 1.95 Mev are 330 and 30 mb, respectively. The ${\mathrm{C}}^{12}(t, \alpha ){\mathrm{B}}^{11}$ reactions may proceed by a "direct cluster exchange interaction" in which the distortion effects may play an important part.

• Received 1 September 1961

DOI:https://doi.org/10.1103/PhysRev.125.648