In this chapter, I will discuss the mechanisms of interaction
of gamma radiation with matter. That will lead
directly to an interpretation of the features within a gamma
spectrum due to interactions within the detector itself
and within the detector surroundings. Finally, the design
of detector shielding will be considered. Although the
discussion will centre on gamma radiation, it should not
be forgotten that gamma radiation is electromagnetic in
nature, as is X-radiation, and that to a detector they are
indistinguishable.