Which tool is commonly used to detect gamma rays?

Gamma rays are a form of high-energy electromagnetic radiation, and their detection requires specialized instruments that can effectively measure their intensity and presence. A Geiger counter is designed specifically for the detection of ionizing radiation, including alpha particles, beta particles, and gamma rays. It does this by converting the energy from the radiation into electrical signals, which can then be counted.

The effectiveness of a Geiger counter in detecting gamma rays stems from its construction, which often includes a Geiger-Müller tube that produces a pulse of current when it interacts with ionizing radiation. This makes it an ideal tool for measuring the radiation levels in various contexts, including safety monitoring in areas where radioactive materials may be present.

In contrast, other tools like photodiodes are mainly used for detecting light and are not sensitive to high-energy radiation like gamma rays. A black light emits ultraviolet light, unrelated to gamma rays, and does not have the capability to detect radiation. A thermometer measures temperature and has no function in detecting any form of radiation. Therefore, the Geiger counter stands out as the correct choice for the detection of gamma rays.