Related Experiment Video
Updated: Aug 15, 2026

Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator
Published on: May 9, 2014
Polarity effect of the thimble-type ionization chamber at a low dose rate
Yong-Kyun Kim1, Se-Hwan Park, Han-Soo Kim
1Korea Atomic Energy Research Institute, Daejeon 305-600, Republic of Korea.
Abstract:
It is known that the current collected from an ionization chamber exposed to a constant radiation intensity changes in magnitude when the polarity of the collecting potential is reversed. It is called the polarity effect of the ionization chamber. There are many possible causes that induce the polarity effect and one of them can be a field distortion due to a potential difference between the guard electrode and the collector. We studied how much the polarity effect depends on the design of the electrodes in the thimble-type ionization chamber. Two thimble-type ionization chambers, which had different electrode structures, were designed and fabricated at KAERI. We calculated the field distortions due to the potential difference between the guard electrode and the collector for the two ionization chambers. MAXWELL and Garfield were employed to calculate the electron drift lines inside the chamber. The polarity effects of the two ionization chambers were measured, and they were consistent with the field calculation. We could conclude that the polarity effect is mostly induced from the field distortion due to the potential difference between the guard electrode and the collector in our experiment and it depends significantly on the design of the electrodes.
Related Concept Videos
Diamagnetic Shielding of Nuclei: Local Diamagnetic Current
Potential Due to a Polarized Object
Biological Effects of Radiation
Ionization Energy
Thomson's e/m Experiment
A particle with charge q, speed v, and mass m enters an area from the top, where the magnetic and electric fields are perpendicular both to the particle's motion and to one another. The magnetic...
Induced Electric Dipoles
Since the absolute value of potential energy holds no physical meaning, its zero value can be chosen as per...

