FOCUS, aka E831, is a heavy-flavor photoproduction experiment located in the Wide Band
Area of Fermilab. It
is an upgraded version of its predecessor, E687.
The experiment accumulated data during the 1996-1997 fixed target run and has
fully reconstructed more than one million charm particles using the `golden
mode' decays, D0→ K−
π+,D0→ K− π+
π− π+, and D+→
K− π+ π+.