A muon leaves a track in the track detector and a mark (a cross) in the muon detector. Remember that the track and the cross should be coloured with a bright shade since the muon is a charged particle. Use the muon detectors in WIRED to identify muons.
The muon detector is also the key to identify neutrinos. Since neutrinos only interact weakly with matter they will pass through DELPHI without leaving any trace. Sometimes one can guess if there were neutrinos in an event by comparing the collision energy to the detected energy. Since the neutrinos leave the detector with some energy, will the detected energy be smaller than the collision energy. The neutrinos are often quite energetic which will cause the detected energy to be significantly smaller than the collision energy.
However, the method to recognise neutrinos is not foolproof. Sometimes other particles disappear (e.g. into the beam pipe) with energy that is not detected by DELPHI. The uncertainty about neutrinos is also caused by the energy measurements of jets, which is not exact.