An air-filled cavity used for radiation detection is referred to as what?

An air-filled cavity utilized for radiation detection is known as an ionization chamber. This device operates based on the principle that ionizing radiation, when it passes through the air in the chamber, will ionize the air molecules. This ionization process generates free electrons and positive ions, which can be collected to produce an electrical current. The amount of current generated is proportional to the amount of radiation present, allowing for measurement of radiation levels.

Ionization chambers are specifically designed to measure the intensity of ionizing radiation and are commonly used in various applications, including environmental monitoring, radiation therapy, and radiological protection. They provide accurate readings and are particularly effective for measuring dose rates in situations where radiation levels fluctuate.

In contrast, other devices mentioned in the options serve different purposes. Photomultiplier tubes are used to amplify the signal from low levels of light, scintillation crystals convert radiation into visible light for further detection, and radiographic film captures images of radiation patterns but does not measure radiation levels directly. Therefore, the ionization chamber is the accurate term for an air-filled cavity in the context of radiation detection.