Which of the following is a type of ionization chamber?

The Geiger (GM) counter is a type of ionization chamber, which functions by detecting radiation through the ionization of gas within the chamber. When ionizing radiation passes through the gas, it causes ion pairs to form—positive ions and free electrons. This ionization process creates a measurable electrical pulse, which is then counted as an event. GM counters are commonly used for their ability to detect a range of ionizing radiation including alpha particles, beta particles, and gamma rays, making them versatile and useful in various applications such as radiation survey and monitoring.

In contrast, the other options represent different types of radiation detection methods. A film badge utilizes photographic film to measure cumulative exposure to ionizing radiation but does not operate based on ionization of a gas. A scintillation counter detects radiation by measuring the light (scintillations) produced when radiation interacts with certain materials, converting that light into an electronic signal. A thermoluminescent dosimeter (TLD) measures radiation exposure by employing materials that emit light when heated, indicative of previous radiation exposure, but again, does not involve ionization in the same way as a GM counter.