2. Energetics of nuclear reactions

In practice, to characterize the energy and direction of -particles resulting from a nuclear reaction, we have to consider two reference frames:

• the laboratory reference frame (L) is a fixed coordinate system associated with the experimenter/observer;

• the reference frame of the center of mass, noted (CM), is a moving coordinate system that depends on the relative position of the projectile and the target.

Figure 2 illustrates these two concepts in the case of an incident particle of mass m ₁ colliding with a particle of mass m...