The proton pack is a fictional energy based capture device, used for capturing and entraping ghosts. Ghostbusters universe. First depicted in the film Ghostbusters, it has a hand-held wand (Neutrino Wand or particle thrower) connected to a backpack-sized particle accelerator. It fires a stream of highly focused and radially polarized protons that electrostatically traps the negatively charged energy of a ghost, allowing it to be held in the stream.