Which of the following can be used to determine the barrier thickness needed to attenuate radiation?

The half-value layer is a critical concept in radiation protection and shielding that helps determine the thickness of material needed to attenuate radiation to a desired level. Specifically, the half-value layer refers to the thickness of a specified material that is required to reduce the intensity of radiation to half of its original value. This property is essential for designing barriers in settings where radiation exposure must be controlled, such as in medical facilities, nuclear power plants, and research labs.

By knowing the half-value layer for a given type of radiation (such as gamma or X-rays) and the material being used for shielding, operators can effectively calculate how thick the barrier must be in order to achieve adequate radiation protection. This is vital for ensuring the safety of both personnel and the public by minimizing exposure to harmful radiation.

In contrast, the other options provided do not directly relate to the concept of barrier thickness in radiation shielding. Pair production is a process that involves the conversion of photon energy into matter but does not provide a means for calculating material thickness. Newton's 2nd law pertains to the motion of objects and forces, which is not relevant to radiation attenuation. Planck's constant relates to the quantum mechanics of photons and energy levels rather than practical applications for determining shielding thickness. Thus,