The physics of a liquid filled ionization chamber with pulsed polarizing voltage

A simple model is presented that describes the physics of a liquid-filled ionization chamber that is operated with a pulsed polarizing voltage. The chambers are applied in this way in a scanning matrix ionization chamber device that is used in a medical application. The signal to noise ratio can be made very high due to the long ion lifetime in some liquids. The effective integration time in the liquid of 0.5 s yields a low-quantum noise contribution and at the same time time ensures a fast response time of the chamber. The charge collection efficiency is somewhat low, but the amount of collected charge (1 pC) can be detected without adding too much noise.<>