In order for radiation to be measured, it must interact with which component?

The correct choice is the detector because radiation measurement relies on the interaction between the incoming radiation and the detector material. Detectors, such as Geiger-Müller tubes, scintillation counters, or semiconductor detectors, are specially designed to convert the energy of the incident radiation into a measurable signal, usually in the form of electronic pulses.

When radiation passes through or interacts with the detector, it can cause ionization or excitations in the detector material. This interaction generates charge carriers or produces photons, which can then be amplified and counted, allowing the measurement of the radiation intensity. The efficiency and effectiveness of a detector depend on its design and the type of radiation it is intended to measure, but the fundamental principle is always that the radiation must interact with the detector for it to be quantified.

In contrast, shielding material is used to protect the surroundings from radiation, the radiation source generates the radiation, and calibration devices are used to ensure that detectors are providing accurate measurements; however, none of these components are responsible for the direct measurement of radiation itself.