Spinning test particles in the field of a black hole

It is studied the motion of spinning test bodies in the gravitational field of a rotating black hole, confining the examination of the pole-dipole approximation and of the special case of motion in the equatorial plane with the spin vector perpendicular to it. The study also provides the locus of the turning points for the equatorial orbits and also the exact limits of validity of the pole-dipole approximation for any given set of particle parameters. The innermost stable circular orbits are studied in details, and it is found that opposit spinning accreting particles are separated by the gravitational field of the black hole and that the fraction of energy ''at infinity'' which can be extracted when the particle spin is opposite to that of the black hole can be as high as 100%