Refractive behavior in intermediate-energy alpha scattering

• DOI: 10.1103/physrevc.10.1362
• Publication Date: 2002-07-26T23:27:59Z
• Authors: D. A. Goldberg; S. M. Smith; G. F. Burdzik
• Keywords: Rainbow; Woods–Saxon potential

We report on recent $\ensuremath{\alpha}$-scattering experiments at 141.7 MeV using $^{40}\mathrm{Ca}$ and $^{90}\mathrm{Zr}$ targets. The results are compared with previous other nuclides approximately the same energy used to illustrate phenomena occurring in intermediate-energy $\ensuremath{\alpha}$ scattering which we have given name "refractive behavior." All elastic differential cross sections exhibit exponential-like falloff large angles characteristic of nuclear rainbow scattering. variation angle $A$ is found be linear. In each instance it shown that, consistent earlier predictions, data beyond make possible elimination discrete ambiguities optical potential: For nucleus studied, only a single family Woods-Saxon potentials fit data. real parts extracted characterized by well depths ranging from 108 118 volume integrals $\frac{J}{4A}$ 297 352 ${\mathrm{fm}}^{3}$; hence they more nearly three times strength nucleon-nucleus 1/4 incident energy, rather than 4 times, as frequently assumed. Systematic variations occur primarily imaginary part potential greatest for lighter nuclei; decreases, $W$ ${a}^{\ensuremath{'}}$ decrease, $r_{0}^{}{}_{}{}^{\ensuremath{'}}$ increases, integral increases.NUCLEAR REACTIONS $^{40}\mathrm{Ca}$, $^{90}\mathrm{Zr}(\ensuremath{\alpha},\ensuremath{\alpha})$, $E=141.7$; enriched targets; measured $\ensuremath{\sigma}(\ensuremath{\theta})$; deduced optical-model parameters, angles; those $^{58}\mathrm{Ni}$, $^{12}\mathrm{C}$.