Direct Interaction Processes Research Articles

The investigation of the mechanism of the Cr52 (d, p) Cr53 reaction

The Cr52(d, p)Cr53 reaction has been investigated at deuteron energies in the range 3.29 to 4.4 MeV. The measurements reveal the importance of the direct interaction process. The small angle part of the angular distribution could be fit with Butler's Ln = 1 curves. However, important deviations from the simple Butler theory have been found, which seem to be caused by the interference between stripping and compound nucleus formation. A pronounced secondary maximum evolved around 65°, and possible explanations of it are discussed.

Angular Distributions of Elastically and Inelastically Scattered Protons from Indium

Thin targets of natural indium were bombarded with 7.04-Mev protons, and the scattered particles were analyzed with a magnetic spectrograph. Inelastically scattered protons were observed corresponding to excited states in ${\mathrm{In}}^{115}$ at 1.078, 1.135, 1.292, and 1.982 Mev. Measurements were made on the variation of the absolute cross sections for elastic and inelastic scattering, and it is concluded that a direct interaction process is important in the excitation of these states.

Proton-alpha reactions in light and heavy nuclei

Nuclear emulsion has been irradiated with 45 MeV protons, and measurements made on the tracks of alpha-particles emitted from disintegrations of the light and heavy nuclei within it. There is a forward excess of energetic alpha-particles in each case, and this can be accounted for by direct interaction processes, for which several possible models are discussed. Conclusions are drawn on the probability of finding alpha-particles in nuclear matter, and on their momentum distribution.

Single Particle Transition in Neutron Inelastic Scattering by Deformed Nuclei

The contribution from the direct interaction process to the nucleon inelastic scattering changing the intrinsic configuration of the deformed nucleus is investigated. The perturbation calculation, with the zero-range two body force, is carried out using waves distorted by the collective surface interaction. The resulting cross section is small compared with the cross section for the usual rotational excitation and justifies the approximation contained in the latter calculation. (auth)

The Energy and Angular Distributions of the Protons from the Reaction60Ni(n, p)60Co Induced by 13.5 MeV Neutrons

The energy spectrum and angular distribution of the protons emitted from'60Ni on bombardment with 13.5 Mev neutrons have been studied using photographic emulsions. About 30% of the protons emitted can be attributed to direct interaction processes.

Theory of Direct Interaction in Nucleon Inelastic Scattering

For the i.nelastic scattering of nucleons at low and intermediate energies an approximate method is proposed by which the direct interaction process is calculated. From the coupled equation for the radial wave functions in various channels a standing wave solution is obtained by perturbation ap· proximation. For the asymptotic form of the wave function in outgoing channel we choose a proper form in such a way that the higher order contributions in perturbation expansion become small. The generalized K·matrix is calculated from the first order solution and later the S-matrix is transformed from the K-matrix. This method can give the exact solution in some simple cases and also is expected to give a good approximation in general cases. By assuming the simple zero-range force between nucleon in the nucleus and the incident neutron :the approximate method is applied to the inelastic scattering of neutrons by Mg24• The effect of the Pauli principle is also estimated. The same process is calculated by assuming the collective excitation .and both results are com pared.

Angular Distributions of Protons from the Alpha-Particle Bombardment ofB10,Al27, andP31

Angular distribution measurements have been carried out on the protons corresponding to the ground state transition in the ${\mathrm{B}}^{10}(\ensuremath{\alpha}, p){\mathrm{C}}^{13}$ reaction at bombarding energies of 8.1, 7.0, and 4.9 Mev, on the protons corresponding to the ground state and first-excited state transitions in the ${\mathrm{Al}}^{27}(\ensuremath{\alpha}, p){\mathrm{Si}}^{30}$ reaction at bombarding energies of 8.1 and 7.1 Mev, and on the protons corresponding to the ground state transition in the ${\mathrm{P}}^{31}(\ensuremath{\alpha}, p){\mathrm{S}}^{34}$ reaction at bombarding energies of 8.1 and 7.0 Mev. According to rather qualitative criteria concerning the changes in the shapes of the distributions with bombarding energy, the Al results appear to be interpretable in terms of a compound nucleus process, while the B and P results indicate the possibility of a contribution from a direct interaction process. Some discussion is given concerning the possibility of applying a direct interaction process like that of Austern, Butler, and McManus to such alpha-particle-induced reactions.