If you have a proton and an anti-proton travelling in the same direction with momentum from A to B but during the flight time they become attracted due to thier opposite charges and annilhilate, the momentum I would guess is transfered to the resulting unstable K particles mesons etc, which, as I understand it, further breakdown into Electro Magnetic Radiation (Gamma Rays?) and Neutrinos. It seems to me from my limited research in positron/electron annihilation that each fundamental particle pair (electron/positron and quark/anti-quark) eventually decays into a Gamma Ray pair of equal strength and opposite direction (180 degrees) possibly at 90 degrees to the point of annihlation. Can I assume that the original momentum of the proton and anti-proton would be dectable in the wavelengths of the resulting gamma rays? Or is the momentum transferred to the Neutrinos?