What type of radiation measurement technique utilizes ionization of air?

The correct answer is the ionization chamber, which is a device that directly measures radiation levels based on the ionization of air. When ionizing radiation passes through the chamber, it interacts with the air molecules, causing them to become ionized, which means they lose or gain electrons and form charged particles. These charged particles can then be collected and measured, allowing the ionization chamber to quantify the amount of radiation present in the environment.

Ionization chambers are widely used in various applications, including radiation safety monitoring and measurement in medical settings, because they provide real-time results and are effective in detecting different types of ionizing radiation, such as alpha, beta, and gamma particles. The principle of measuring ionization is key to their functionality and reliability.

The other techniques listed, such as photographic plates, aerosol sampling, and thermal neutron capture, do not primarily rely on the ionization of air for radiation measurement. Photographic plates record radiation exposure through chemical changes in a film, aerosol sampling focuses on collecting airborne particles rather than measuring radiation directly, and thermal neutron capture involves interactions with specific materials rather than air ionization. This clarity on what differentiates these techniques highlights why the ionization chamber is the correct choice.