  We study the process of mass segregation through 2-body relaxation in
galactic nuclei with a central massive black hole (MBH). This study has bearing
on a variety of astrophysical questions, from the distribution of X-ray
binaries at the Galactic centre, to tidal disruptions of main-sequence and
giant stars, to inspirals of compact objects into the MBH, an important
category of events for the future space borne gravitational wave interferometer
LISA. In relatively small galactic nuclei, typical hosts of MBHs with masses in
the range 1e4-1e7 Msun, the relaxation induces the formation of a steep density
cusp around the MBH and strong mass segregation. Using a spherical stellar
dynamical Monte-Carlo code, we simulate the long-term relaxational evolution of
galactic nucleus models with a spectrum of stellar masses. Our focus is the
concentration of stellar black holes to the immediate vicinity of the MBH.
Special attention is given to models developed to match the conditions in the
Milky Way nucleus.
