Which term refers to the reduction of radiation intensity as it passes through matter?

The term that indicates the reduction of radiation intensity as it travels through matter is attenuation. Attenuation encompasses all the processes that lead to the decrease in the intensity of radiation, which includes both absorption and scattering.

As radiation encounters matter, some energy is absorbed by the material, while some may scatter in different directions. An important aspect of attenuation is that it is a collective term that reflects the cumulative effect of both absorption and scattering, giving a comprehensive understanding of how much radiation is ultimately reduced.

In contrast, scattering refers specifically to the deflection of radiation in various directions, while absorption pertains directly to the energy loss due to the radiation being taken in by the material. Penetration describes the ability of radiation to pass through a material but does not account for the reduction of energy. Thus, attenuation is the most accurate term to describe the overall decrease in radiation intensity as it moves through matter.