Open heavy flavor measurements with PHENIX at RHIC

The production of heavy flavor, i.e. charm or beauty quarks, is an important
probe of the hot and dense medium created in high energy nuclear collisions.  
Heavy quark-antiquark pairs are produced dominantly in initial hard parton
scattering processes and form either bound quarkonia or hadronize into
separate particles carrying open heavy flavor. The latter do not only
provide an important baseline for quarkonia measurements but are a sensitive
probe of the medium themselves.

One approach to study heavy flavor in nuclear reactions is to investigate
the leptonic decay channels of particles carrying heavy flavor. At RHIC, the
PHENIX experiment has conducted a systematic study of open heavy flavor
production in p+p, d+Au, and Au+Au collisions at 200 GeV.  Selected results
will be discussed.