Calculation Of Multi-step Compund Pre-equilibrium Cross Section For Deuteron Emission In Some Proton-induced Nuclear Reactions
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Date
2015
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Obafemi Awolowo University
Abstract
This study adapted the computer code GAMME (which was originally written for single particle emission) for deuteron emission, calculated the multistep compound reaction cross sections using the Feshbach-Kerman-Koonin (FKK) theory and compared the results with the appropriate experimental data. This was with a view to generating MSC nuclear parameters for (p,d) reactions.
A computer code “GAMME” written by Bonetti and Chadwick was modified to calculate the multistep compound (MSC) double-differential emission cross sections for 90Zr(p, d), 58Ni(p, d) and 209Bi(p, d) at 42 MeV incident energy. Zero-range and Yukawa forms were used for the residual proton-deuteron interaction potential. To calculate the wavefunctions for the projectile and the ejectile, the optical potential parameters , and Perey were used for protons while the parameters of Perey-Perey and those of Lohr-Haeberli were used for the deuterons. The level density parameters of Gilbert and Cameron were also used in the calculations. The calculated double-differential cross sections at the backward angle of 150o were compared to the experimental data of Watanabe et al.,(1998, 1999). This was done because it was believed that at this angle, the MSC processes made the most significant contribution to the cross section. Compound nucleus reaction contribution to the reaction cross section was also calculated in order to find better agreement between theoretical values and experimental values of the cross section.
A good correlation was obtained between the theory and experiment by adjusting the value of the residual potential strength, V0, that was used for the MSC calculation. The contribution of compound nucleus (CN) emission to the total cross sections was found to be negligible for 90Zr reaction. For 58Ni and 209Bi reactions, CN emissions contributed significantly at the lower energies (17-18 MeV), but at the higher energies (25 MeV and above), the contributions were negligible. Also, the V0 of the Yukawa potential was much larger than the one obtained for the Zero range. This showed that the Yukawa potential was weaker than zero range at the backward angles. The calculated double-differential cross section showed significant sensitivity in magnitude, to deuteron-particle optical potentials but showed little response to proton optical potentials.
The study concluded that the contribution of the MSC reaction to the total pre-equilibrium reaction cross sections for the (p, d) reaction was significant, although there were discrepancies at the higher energy regions attributable to multi-step direct (MSD) emission which were not included in the calculation.
Description
93 Pages
Keywords
Deuteron emission, Feshbach-Kerman-Koonin, Nuclear Reactions, GAMME, Bechetti-Greenless,prerey
Citation
Awoyemi I.A (2015)Calculation Of Multi-step Compund Pre-equilibrium Cross Section For Deuteron Emission In Some Proton-induced Nuclear Reactions.Obafemi Awolowo University.