  In TeV scale unification models, gravity propagates in 4+d dimensions while
gauge and matter fields are confined to a four dimensional brane, with gravity
becoming strong at the TeV scale. For a such scenario, we study strong
gravitational interactions in a effective Schwarzschild geometry. Two regimes
appear. For large impact parameters, the ratio rho=(Rs/ro)1+d, (with Rs the
Schwarzschild radius and ro the closest approach to the black hole), is small
and the deflection angle is proportional to rho (like Rutherford-type
scattering).For small impact parameters, the deflection angle develops a
logarithmic singularity and becomes infinite for rho=rho crit= 2/(3+d). This
singularity is reflected into a strong enhancement of the backward scattering
(like a glory-type effect). We suggest a distinctive signature of black hole
formation in particle collisions at TeV energies, the observation of the
backward scattering events and its associated diffractive effects.
