This scenario is identical to the classic double slit screen experiment except that the photon is at extremely high energy. The energy is so high that the photon's momentum maybe registered by a mechanical measuring device(i.e spring or accelerometer attached to a receiver). At the moment of emission(before the photon has hit the screen/receiver) the emitter will recoil with the momentum opposite to the photon's. Surely this would give us information about the path of the photon before the photon is registered at the screen/receiver? What stops the wave function from being collapsed?