EFFECTS OF DISTORTION IN (CX, 2CX) REACTION

Abstract

In this work we have studied the (?, 2?) reactions in light nuclei in the energy range, 25-28 Mev. This investigation is performed in the distorted wave impulse approximation (DWIA) for the interaction of the bombarding a-particle with the a-cluster in the nucleus. The ?-? interaction is described by using a potential with a repulsive core. This potential has a form similar to that used by Hiura and Shimodaya. Our potential satisfies most of the properties of the usual phenomenological potential which can fit the ?-? scattering data well. The distortion effects on the differential cross-section are investigated by employing the wave function of McCarthy and Pursey. The angular correlation distribution is calculated for the case of symmetric coplanar scattering. The differential cross-section in the impulse approximation can be split into the product of two terms, namely, the effective ?-? scattering cross-section and the momentum distribution function. Effects of distortion and of varying the a-a potential parameters on these two terms are studied. Calculations in the plane wave approximation are also carried out for comparison purposes. Distortion effects are found to fill up the dip at the minimum, shift the maximum of the distribution curve slightly to the left and enhance the cross-section at small angles. All these three effects are desirable in fitting the experimental data. The variation of the ?-? potential parameters has only one main significant effect. It shifts the whole distribution curve to one side, the effect being greater at small angles. Satisfactory agreement between our calculations and experimental data are found for the Li6 , Li7, Be9 and O16 nuclei. The position of dip and peak of the distribution curves, as well as the peak-to-valley ratio ore well produced. However, in the O12(?, 2?) Be8 reaction, no reasonable agreement between the theory and experiment is observed. Off-energy-shell effects are taken into account in this work. It is found that it is, essential to use a potential with repulsive core in order to obtain reasonable fits to experimental data.