Which statement correctly describes ionization chamber measurement?

Which statement correctly describes ionization chamber measurement?

• A. It measures ionization without amplification
• B. It measures ionization with amplification
• C. It detects energy of gamma photons
• D. It measures dose rate directly

Answer: (A)

Ionization chamber measurement hinges on the gas being ionized by radiation and then the resulting ion pairs being collected by an electric field. The signal is a current proportional to how quickly ion pairs are created, and there is no internal gas multiplication or amplification inside this type of detector. That lack of amplification is the defining feature: it registers the amount of ionization directly, rather than producing amplified pulses. Because it only measures the ionization rate, it does not directly provide the energy of individual gamma photons; energy information would require a different detector. Dose rate can be inferred from the measured ionization with calibration, but the fundamental action of the device is to measure ionization without amplification, which makes that statement the best description.

Ionization chamber measurement hinges on the gas being ionized by radiation and then the resulting ion pairs being collected by an electric field. The signal is a current proportional to how quickly ion pairs are created, and there is no internal gas multiplication or amplification inside this type of detector. That lack of amplification is the defining feature: it registers the amount of ionization directly, rather than producing amplified pulses. Because it only measures the ionization rate, it does not directly provide the energy of individual gamma photons; energy information would require a different detector. Dose rate can be inferred from the measured ionization with calibration, but the fundamental action of the device is to measure ionization without amplification, which makes that statement the best description.