MUFFIN tries to find combinations of a full muon track with a wire readout track. The wire readout tracks are track segments for which one coordinate is unknown. If the track is found in the barrel region this unknown coordinate is Z, if the track is in the rear region the unknown coordinate is X. MUFFIN tests whether for both tracks the angle between the track and the combined track is smaller than . This test is performed in the plane where the coordinates and the direction vectors are known, so either in the X-Y plane for wire tracks from the barrel region or the Y-Z plane for the rear region.
For the combined tracks the missing coordinate is estimated from the full track. Then MUFFIN performs a minimization ( MINUIT) [37] using the calorimeter information. It maximizes the sum of the track trajectories through all calorimeter cells that have energy. If the angle between the full track and the resulting trajectory is less than and the track hits any calorimeter cells with energy, the combined track is kept.