  Scenarios of large extra dimensions have enhanced the importance for the
study of black holes in higher dimensions. In this paper, we analyze an
axisymmetric system of two black holes. Specifically, the Bowen-York method is
generalized for higher dimensions in order to calculate the initial data for
head-on collision of two equal-mass black holes. Then, the initial data are
evolved adopting the close-slow approximation to study gravitational waves
emitted during the collision. We derive an empirical formula for radiation
efficiency, which depends weakly on the dimensionality. Possible implications
of our results for the black hole formation in particle colliders are
discussed.
