ABSTRACT
This chapter shows that the values of almost all nuclear cross sections are dependent on the kinetic energy of the incoming neutrons. Essentially, a nuclear cross section is a convenient way of measuring the probability that an incoming particle will hit the nucleus and, as the result of that collision, cause a particular nuclear reaction or set of reactions to occur. There is a direct correlation between the size of a nuclear cross section and the cross-sectional area of the nucleus that the incident particle is trying to hit. To determine the value of a nuclear cross section, one simply points a beam of particles with a well-defined energy at an object and measures the attenuation of the beam as it passes through the object. Nuclear cross sections can be explained in terms of the internal structure of the nucleus. The cross section for a particle being removed from the beam is called the removal cross section for that particle.
