ABSTRACT

We present below the kinematics of nuclear or particle reactions where two bodies interact with each other to result in two or more bodies in the final state. We specify the bodies in the initial state as a(ma,Ea, ~pa,~va) and b(mb,Eb, ~pb,~vb) in the laboratory, where m, E, ~p and~v are, respectively, the mass, energy, momentum, and velocity of a particle. In the laboratory, the center of mass moves at a velocity

~vcm = ~pa+ ~pb Ea+Eb

(B.1)

In the center of the mass frame, the center of mass is at rest and it is called the zero momentum frame. In this frame, the net momentum of the initial state bodies and also that of the final state bodies is zero. Thus, viewed from the center of mass frame, the particles in the initial state will approach with equal and opposite momenta. In the same frame, the two body final state products recede with equal and opposite momenta. In the many-body final state, the vector sum of the total momenta of all particles is zero.