Interactions of Neutrons with Matter

Abstract

In this chapter we discuss the various types of photon interaction with absorbing media. Photons are indirectly ionizing radiation and they deposit energy in the absorbing medium through a two-step process: (1) in the first step energy is transferred to an energetic light charged particle and (2) in the second step energy is deposited in the absorbing medium by the charged par- ticle. The energy transferred to charged particles from the interacting photon generally exceeds the energy subsequently deposited in the absorbing medium by the charged particles, because some of the transferred energy may be radi- ated from the charged particles in the form of photons. Some of the photon interactions are only of theoretical interest and help in the understanding of the general photon interaction phenomena, others are of great importance in medical physics, since they play a fundamental role in imaging, radiotherapy as well as radiation dosimetry.