Reaction-Product Velocity-Measurements for the O-16+O-16 and C-12+NE-20 Systems

The average Doppler shifts of characteristic γ rays from nuclei produced in the 16O + 16O and 12C + 20Ne reactions have been measured. Recoil velocities deduced from these data are shown to be sensitive to the heavy-ion reaction mechanism. Possible signatures of fusion-evaporation, direct-transfer or inelastic scattering, deep inelastic, and incomplete fusion processes are discussed

STATISTICAL-MODEL CALCULATION OF THE SELECTIVE EXCITATION OF HIGH-SPIN STATES IN 24Mg

Le peuplement sélectif d'états de haut spin dans le 24Mg par la réaction 12C(16O, α)24Mg, de même que l'absence d'une telle sélectivité dans la réaction 14N(14N, α)24Mg peuvent être expliqués par des calculs faits dans le cadre du modèle statistique de Hauser-FeshbachThe selective population of high-spin states in 24Mg by 12C(16O, α)24Mg reaction, as well as the lack of such selectivity in the 14N(14N, α)24Mg reaction, can be explained in terms of a Hauser-Feshbach statistical-model calculation

Gamma-Ray Studies of C-12+Ne-20 Reactions

Excitation functions for the yields of ten residual nuclides from the 12C+20Ne reaction have been measured over the range Ec.m.=11-33 MeV in steps of 150 keV, using γ-ray techniques. The magnitude and energy dependence of the excitation functions for most partial yields, as well as for the total fusion yield, closely resemble those from the 16O+16O system when compared at the same compound-nuclear excitation energy. The total fusion yield exhibits strong anomalies at Ec.m.=22.7 and 24.1 MeV, while the 20Ne inelastic scattering yield exhibits a strong uncorrelated structure at Ec.m.=21.1 MeV. In addition weaker structure is seen at Ec.m.=13.6, 16.6, 18.6, and 26.3 MeV in the total fusion yield. The 24.1 MeV resonance corresponds to a characteristic structure in the 16O+16O reaction yields. Both structures appear at the same 32S excitation energy and are found to be correlated with the transition to a regime of limited fusion

Inclusive alpha-particle Production in the C-12+C-12 Reaction

The α-particle yield from 12C + 12C has been measured for Ec.m.=12-31.5 MeV. The data exhibit many resonantlike structures, some of which are correlated with inelastic-scattering resonances. An anomalously large yield is observed in the Ec.m.=12-18 MeV region. The remarkable similarity in α-particle yields from 12C + 16O and 12C + 12C above Ec.m.=18 MeV and the abrupt change in the nature of the resonant structure below this energy are discussed

16O(16O, 12C)20Ne REACTIONS

On a mesuré la section efficace différentielle de la réaction 16O(16O, 12C)20Ne conduisant à l'état fondamental et à l'état 2+ à 1,63 MeV du 20Ne, ainsi qu'à un état pouvant être l'état 4+ à 4,25 MeV du 20Ne ou l'état 2+ à 4,43 MeV du 12C, ou les deux. Les mesures ont été faites entre 17,5 MeV et 30 MeV (c. m.) à environ 90°, 75° et 60° (c. m.). Les fonctions d'excitation montrent à la fois une large structure et une structure fine, dont les largeurs sont respectivement 1,5 MeV et 0,5 MeV. De fortes corrélations existent entre les fonctions d'excitation à différents angles ainsi qu'entre différents états finals.Differential cross sections from 17.5 to 30 MeV c. m. energy at about 90°, 75° and 60° (cm) have been measured for 16O(16O, 12C)20Ne reactions leading to the ground state, the 1.63 MeV 2+ state, and the 4.25 MeV 4+ state of 20Ne and/or the 4.43 MeV 2+ state of 12C. The yield curves have both gross and narrow structures of ~ 1.5 and ~ .5 MeV in width respectively. Strong correlations are seen among the yield curves for different angles and also among those for different final states