ABSTRACT
The quantum mechanics of the nucleus is beyond the scope of this book, and we therefore proceed with a simple qualitative picture, employing empirical data from the nuclear physics community. A potential energy diagram of a particle interacting with a nucleus is presented in Figure 7.1. For an incident particle to reach the attractive nuclear regime of a nucleus, it must have sufficient energy to overcome the repulsive Coulomb barrier (electromagnetic force). The Coulomb barrier is the energy that the incident charged particle must have for the distance of closest approach to be such that the two nuclei just touch:
(7.1) E Z Z (m m ) m (A A )b
+
+
where Z, A, and m are the atomic number, atomic mass, and the mass of the nucleus, and subscripts 1 and 2 denote incident particle and target nucleus, respectively. In reality, the incident particle could be found within the attractive nuclear regime even if the incident particle had energy E0 < Eb because of quantum mechanical tunneling effects.
