The ion chamber responds to the electromagnetic energy and acts as an energy cell. Gamma radiation strikes the argon gas molecules, which are contained under pressure in the cathode of the cell. When the radiation strikes the argon gas molecules, the gas molecules give up electrons, leaving the argon gas molecules as positive ions.

The electron tends toward the anode of the cell. As more and more electrons eject due to the radiation striking the length of the cell, more electrons migrate to the anode. Even with the greatest amount of gamma radiation striking the cell, the collected electrons on the anode only generate a picoamp level of current.

The positively charged argon molecule now gravitates to the cathode as a bias voltage applies to the cathode. The argon molecule then picks up a replacement electron, which permits the molecule to become stable again.

The performance of the cell relates directly to several parameters. The cell volume, bias voltage, anode and cathode construction, inert gas in the cell, and other design considerations play an important role to the cell’s performance and response to gamma radiation.

For continuous level applications such as the wood chip bin, the desired response is an increasing output proportional to an increasing amount of gamma radiation striking the detector.

The central conductor carries the picoamp current to an amplifier, where the signal is amplified and conditioned and then output as a frequency signal to remote mounted electronics, external to the detector, or further processed on integral electronic boards within the detector housing. The resultant signal from the electronics is a 4–20 mA DC current signal.

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