How a Geiger Counter Meter Works

Geiger counter meters also known as Geiger-Muller counters are used to detect ionizing radiation. This type of radiation is considered a health hazard. Acute exposure causes damage to living tissues. Radiation skin burns can be the result. And at low doses individual can develop cancer, tumors and other conditions caused by genetic damage. Radiation is however not always negative, it has been harnessed for use in the medical setting in procedures such radiation in cancer therapy.

A Geiger counter meter functions on the basis of the physical properties of plasmas. Plasma is not quite a gas, it is a state of matter in which the gas atoms have lost negatively charged electrons, therefore plasma is composed of electrons and positively charged atoms. The gas is said to be ionized. Plasmas conduct electricity, gases do not. Gases are ionized by radioactive materials. A radioactive material emits fast moving electrons and ions which collide with the gas atoms ionizing it.

A Geiger counter is basically a metal tube that contains a thin wire through its middle. The tube also referred to as the Geiger-Muller tube is sealed off and filled with an ionizable gas. Gases commonly used are helium, neon or argon. Halogens are also added to the tube. A potential difference of +1000 volts exists between the wire and the tube. As the tube is exposed to ionizing radiation, an electron can be knocked off the tube by gamma radiation or a fast moving electron penetrates the tube. The electrons are attracted to the central wire because of its high positive voltage.

The charge also serves to energize the electrons causing them to collide with the gas that is contained within the tube, releasing more electrons. Those electrons collide with more atoms releasing even more electrons. In essence the gas contained within the tube serves to amplify the particles released by the ionizing radiation. When the number of free electrons floating in the tube reaches a threshold, it registers a pulse of electric current. The current is the direct result of electrons as they accumulate around the positively charged wire. Once by the wire electrons eventually draw a current which creates a signal within the Geiger’s circuitry which is connected to the detection tube. Geiger counter meters are able to detect ionizing radiation and also count the different electrons passing through its walls.

The detection of the ionization or the output of the Geiger counter meter is usually a display that reads the output current or can also be a series of audible clicks that increase in intensity as the ionizing radiation increases. The voltage or potential difference in the Geiger counter meter is provided by batteries contained within the unit.

To determine if there is ionizing radiation from a suspect source, one has to simply point the Geiger probe (which contains the tube and inert gas) towards the source. Users must make sure their batteries are charged and that the instrument is properly calibrated to obtain reliable results. Geiger counter meters are used in the science field, medical therapy, and in mining they also have applications in industry protecting workers from harmful radioactive exposure.