What Is a Proportional Counter?

Mary McMahon
Mary McMahon

A proportional counter measures ionizing radiation and provides information about its intensity. Such equipment can be used to quantify emissions in studies, or to detect radiation if it is believed to be present. Scientific suppliers manufacture it, and it is also possible for researchers to build their own for specific applications. In addition to being used in lab settings, it may be included in telescopes, probes, and other devices intended for use in space, where measurements of radiation can provide useful information about the environment.

Scientist with beakers
Scientist with beakers

This equipment includes a chamber filled with gas. As radiation enters it ionizes the gas, creating sets of ion pairs which can in turn create a cascading effect. The proportional counter generates an electrical pulse as the original charged particle moves across the field and is capable of tracking the cascading reactions. These devices are more sensitive than the well-known Geiger counter, which can generate electrical pulses when it detects activity, but can’t discern its source.

Within the proportional counter, a series of electrical fields track the charged particle and the reactions of the ion pairs, providing information. The device can indicate what kind of radiation is involved and how intense it is on the basis of how it behaves in the chamber. Each electrical pulse corresponds to a radioactive particle’s movement through the gas and subsequent series of responses as the ion pairs drift through the medium. These proportional reactions help researchers identify, trace, and understand radiation.

In experimental settings, it can be important to be able to quantify radiation. Researchers want to measure how much is produced in a given activity, and how strong it is. If there are questions about whether radiation is present in an environment, the proportional counter can be used to identify and quantify it, providing valuable follow-up data. Information from proportional counter measurements can be plotted on charts and graphs for the purpose of analysis and comparison.

Astronomers have historically used proportional counters, along with other detection devices, to monitor activity in space. Space is filled with radiation which corresponds to different physics events, like galaxy formation and the death of stars. Monitoring this can provide useful data about the configuration and history of the universe. Some researchers use colorized mapping techniques to create a visual representation of radiation that normally wouldn’t be within the range of human perception, highlighting patterns of activity for the benefit of viewers.

Mary McMahon
Mary McMahon

Ever since she began contributing to the site several years ago, Mary has embraced the exciting challenge of being a wiseGEEK researcher and writer. Mary has a liberal arts degree from Goddard College and spends her free time reading, cooking, and exploring the great outdoors.

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