Which instrument is primarily used to measure radiation levels in an environment?

The Geiger-Müller counter is primarily used to measure radiation levels in the environment due to its sensitivity to various types of radiation, including alpha, beta, and gamma radiation. This instrument consists of a Geiger-Müller tube filled with gas that becomes ionized when radiation passes through it. This ionization generates electrical pulses that can be counted, providing a direct measurement of the radiation levels present in the environment.

The Geiger-Müller counter is favored for its portability, ease of use, and ability to provide immediate readings, making it particularly valuable in assessments of radiation exposure in various settings, such as nuclear facilities or during radiological emergencies. Its design allows for real-time monitoring, which is essential for maintaining safety in environments where radiation is present.