I wrote:
> Take a (hypothetical) near-stationary neutron and an energetic nickel > lattice atom. I believe their interaction is characterized by the > center-of-mass system that takes them both into account -- if the nickel > atom is moving quickly towards the neutron, according to the center-of-mass > system they are moving towards one another at equal velocities. > Not equal, but in this system the neutron is no longer stationary either (actually, I think it might be the neutron that is moving quickly). Needless to say, I suspect there would be occasional reflection. Eric
