The aim of the present study is to make for the first time in the literature a systematic and quantitative assessment of the evaluation of the imaginary part of the optical potential calculated within the folding model and its consequences on the localization of surface reactions. Comparing theoretical and experimental reaction cross sections, for some light projectiles on a ⁹Be target, it has recently been shown that a single-folded s.f. (light-) nucleus-⁹Be imaginary optical potential is more accurate than a double-folded d.f. optical potential. Within the eikonal formalism for the cross sections and phase shifts, the single-folded potential was obtained using a n-⁹Be phenomenological optical potential and microscopic projectile densities. This paper is a follow-up in which we systematically study a series of different light and medium-mass projectile induced reactions on ⁹Be. Our results confirm that the s.f. cross sections are larger than the d.f. cross sections and the effect increases with the projectile mass. Furthermore the strong absorption radius parameter extracted from the S matrices calculated with the s.f. has a stable value $r_s=1.3-1.4$ fm for all projectile masses in the range of incident energies 40-100 A.MeV. This indicates that a clear geometrical separation can be made between the region of surface reactions, the region of strong absorption into other channels and the region of weak nuclear interaction. The d.f. results are instead much scattered and the separation between surface reactions and other channels does not seem to be consistent. Excellent agreement with recent experimental results confirms the validity of our approach.

本研究的目的是在文献中首次对折叠模型中计算出的光学势的虚部及其对表面反应本地化的影响进行系统和定量的评估。比较理论和实验反应截面，对于⁹ Be靶上的某些光弹，最近发现单倍sf（光）核⁹ Be的虚构光学势能比双倍df光学器件更精确潜在。在截面和相移的正规形式内，使用n- ⁹获得单折叠势是现象学的光学潜能和微观弹丸密度。本文是后续研究，我们系统地研究了⁹ Be上的一系列不同的轻中质量弹丸诱导的反应。我们的结果证实，sf横截面大于df横截面，并且效果随着弹丸质量的增加而增加。此外，从使用sf计算的S矩阵中提取的强吸收半径参数具有稳定值${\mathrm{[R}}_s=1.3-1.4$在入射能量40-100 A.MeV范围内的所有弹丸质量的fm。这表明可以在表面反应区域，被其他通道强吸收的区域和弱核相互作用的区域之间进行明确的几何分离。相反，df结果分散很多，并且表面反应和其他通道之间的分离似乎不一致。与最近的实验结果极好的一致性证实了我们方法的有效性。