An instrument designed to measure ionizing radiation. The types of detectors differ according to the particles they are intended to measure, whether they are intended to detect their quantity, energy or composition. There are different ways in which detectors can measure radioactivity, but in general the passage of radiation through a detector will cause a change that can be detected, such as a flash, a change in current or voltage. For example, we recognize the scintillation detector, proportional counter, ionization chamber, trace detector and Wilson diffusion cloud chamber. A dosimeter is a type of detector designed to measure the dose received by a person.