An air-filled chamber used for radiation detection is called which device?

• A. Semiconductor
• B. Ionization chamber
• C. Scintillator
• D. Phototimer

Answer: (B)

An air-filled chamber used for radiation detection works by measuring the ionization produced when radiation passes through the gas. When x-rays or gamma rays interact with the air inside the chamber, they create ion pairs (positive ions and free electrons). An applied electric field across the chamber collects these charges, generating a current that is proportional to the radiation intensity. This direct, gas-based signal is the hallmark of an ionization chamber, making it the go-to device for measuring dose rate and exposure.

This differs from a semiconductor detector, which uses a solid-state junction to detect radiation; a scintillator, which converts radiation to light that is read by a photodetector; and a phototimer, which uses optical light to control exposure timing.