This is a typical case of a muon passing through Inner Detector scintillator in Double Chooz.
Cherenkov light is shown in blue and scintillator in red. Black is where they overlap. Re-emission from wavelength shifters is colored as per the parent photon. In this and all other animations, only a thin cross-section of the detector is shown. Photons appearing out of nowhere are crossing into this section, and photons disappearing may either be exiting it or being absorbed.
This muon misses the Gamma Catcher and so emits only Cherenkov light in the Inner Detector. However, this light interacts with the Gamma Catcher's wavelength shifters, giving isotropic emission. Note also reflections off of the PMTs themselves (not shown, but visible as regions where tracks stop or reflect) and the walls.
Same coloring as above.
This muon starts an electromagnetic shower just above the Inner Veto, resulting in a gamma that reaches the Gamma Catcher along with the muon, but about 500mm to the left, distorting the pattern of light.
Only scintillator light is drawn. Electrons are shown in black, gammas in grey.
This muon stops near the center of the Neutrino Target. Visible in the "instantaneous positions" animation is the large amount of scintillation light at the stopping point due to high dE/dx.
Scintillator and Cherenkov light is shown, both in purple.
A 1.4GeV electron coming out of the steel shield (no muon).
This is reconstructed "correctly" as a buffer muon with approximately the right position.
A 850MeV K- coming out of the steel shield. It stops near the top of the Gamma Catcher, and is captured by a carbon nucleus, giving a Λ and two gammas. The Λ promptly decays to a proton and a pion. The pion captures, giving another gamma. Each gamma starts an EM shower.
This is reconstructed as a stopping muon. The entry point is 3 meters off the truth, but the stopping point is given as near the top of the target, which is the rough center of the set of EM showers.
