Interactions Between Radiation and Matter

Abstract

This chapter describes the interaction between radiation and substances/material. It depends on the type of radiation; electromagnetic wave (gamma ray or X-ray) or particle beams. However, in the case of gamma ray or X-ray, the interaction depends on energy; and in the case of particle beam, it depends on mass and electronic charge (negative or positive or neutral). In the former, microscopically the dominant phenomenon changes from photoelectric effect, Compton effect, to pair production with increasing energy. Macroscopically, its intensity decays exponentially with thickness of substance. In the latter, for the case of negatively or positively charged material, Colonm b interaction (scattering) is dominant, though the collision can occur with less probability; for the case of neutron, collision or capture is a dominant process. These schemes are explained.

Exercises

• 1. Why is the Compton effect the dominant process for the core of Co-60 gamma rays and water?

• 2. Draw a figure of charge in stopping power of a carbon ion of 6 Mev per nuclear (expressed as 6 MeV/u, where u means a nuclear) subjected to water.