American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

The degree of concentration of radioactive material in a gamma ray source is referred to as specific activity. Specific activity represents the activity of a radioactive material per unit mass. It is an important concept in radiographic testing and other applications that utilize radioactive sources. The specific activity indicates how many radioactive disintegrations occur in a given mass of the material per unit time, which is crucial for understanding the characteristics of the source and its efficiency in emitting gamma radiation. High specific activity means that even a small amount of material can produce significant radiation, making it ideal for various industrial applications, including non-destructive testing.

The other options denote different aspects of radioactivity and radiation. Radioactive half-life is the time taken for half of the radioactive atoms in a sample to decay. Radiation intensity refers to the strength of radiation emitted from a source, while the decay constant indicates the probability of decay per unit time for radioactive material. These concepts, while important, do not specifically refer to the concentration of radioactive material within a source.