  Measurements of the elastic scattering angular distribution for the
d+$^{197}$Au system were carried out covering deuteron incident energies in the
range from 5 to 16 MeV, i.e. approximately 50% below and above the Coulomb
barrier. A critical interaction distance of $d_I$= 2.49 fm was determined from
these distributions, which is comparable to that of the radioactive halo
nucleus $^{6}$He. The experimental angular distributions were systematically
analyzed using two alternative models: the semi-microscopic Sao Paulo and the
effective Woods-Saxon optical potentials, for which the best-fitting parameters
were determined. These potentials, integrated in the vicinity of the
sensitivity radius, were calculated for each energy. For both models, the
energy dependence of these integrals presented the breakup threshold anomaly
around the coulomb barrier, a typical signature of weakly bound nuclei.
