Slowing Down of Neutrons in Infinite Homogeneous Media

We have derived from the Boltzmann equation a new integral equation governing the slowing down of neutrons in a homogeneous mixture of atoms. The new equation reflects a view of the neutrons as propagating down the energy scale, whereas the Boltzmann equation expresses a collision balance. Unlike the Boltzmann equation the new equation lends itself to approximate solution by iteration and to the construction of an accurate variational principle for p, the resonance escape probability. Some numerical results are given.