Coupled channels calculations that simultaneously predict elastic scattering and fusion reaction cross sections are compared with the corresponding available measurements for ' 0+ ' Cu collisions. The calculations can reproduce the main features of the fusion and elastic scattering data sets but only separately by using significantly different ion-ion potentials.PACS number(s): 25.70.Bc, 25.70.Jj Two interrelated phenomena in low-energy heavy-ion collisions are the so-called "threshold anomaly" for elastic scattering and the "sub-barrier enhancement" of fusion reactions. The former refers to the notable energy dependence of optical-model potentials obtained from fits to elastic scattering cross sections at energies near the Coulomb barrier. The latter refers to the large fusion cross sections, relative to conventional barrier penetration model predictions, observed at energies below the barrier. Both phenomena are incorporated in a generalization of the barrier penetration model for fusion which allows for couplings to the intrinsic degrees of freedom of the colliding nuclei. The couplings enhance the probability for tunneling through the Coulomb barrier. They also give the important direct reaction cross sections if the relevant low-energy degrees of freedom are properly taken into account. If the fusion and direct processes make up the total reaction cross section, the elastic scattering cross section will also be reproduced.Successful applications of this consistent approach to both fusion and elastic scattering have been reported for Ni+ Ni and S+Ni collisions [1,2]. In the former case, the elastic scattering data were reproduced by calculations which had been done previously to describe the fusion measurements.In the latter case, the calculations suggested that there were inconsistencies in the original data sets. This was indeed confirmed in subsequent measurements.A recent discussion of fusion and elastic scattering measurements for ' 0+ ' Cu has suggested that unusual isotopic and energy-dependent effects are occurring for these systems [3]. To improve upon the analysis in Ref.[3], which made use of separate models to describe the fusion and elastic scattering data, we decided to make a consistent calculation within the coupled-channels framework. Our results, which are presented below, reproduce the main trends of the elastic scattering and fusion data, but not simultaneously.We find that significantly different ion-ion potentials are required for the two types of reactions.The details of our method may be found in Refs. [1,2] and references therein. Here we only briefly comment on the main ingredients of the calculations. The most important input is the bare, ion-ion nuclear potential. For this we use the semiempirical potential of Ref. [4], which is specified for an A, + 32 collision asThe systematics give b, =0. 29 fm (cf. , Ref.[4]). We use b, as a free parameter which is adjusted to fit a given set of data.In addition to the ion-ion potential, we require the couplings to the most relevant direct ...
