How do geiger muller counters work

The device they created is pretty much the same technology that's used today. A Geiger counter is a relatively simple and inexpensive device, consisting of a low pressure gas — typically argon or xenon — in a sealed chamber containing two electrodes. When radiation reaches the counter, it ionizes the gas, freeing negatively charged electrons from atoms and creating positive ions from the part of the atom that remains.

A high-voltage electrical charge is applied to the electrodes, which causes the free electrons to travel to the positive electrode, which is called an anode. Because of the high voltage applied to the electrodes there is a region near the anode where the resulting electrical field is so strong that it creates "avalanches" of secondary electrons when the primary electrons approach the anode, explains Marek Flaska , an assistant professor of nuclear engineering at Penn State University, in an email.

These pulses are large — several volts — so no additional signal amplifier is needed. Those pulses create the clicks that you hear when radioactive particles enter the device and cause ions and electrons to split apart. The number of clicks that you hear indicates how many times this is happening in a minute. In addition, there's usually a display that indicates the count. The level of radiation counted by a Geiger counter is expressed in a unit called microSieverts, per hour of exposure.

One sievert is 1, milliSieverts and 1 million microSieverts. So if the Geiger counter reads 0. Some basic numbers to use as a guide: A single-organ CT scan gives a radiation dose of about 6, microSieverts , according to Reuters, while 2,, microSieverts of exposure would indicate severe radiation poisoning leading to possible death, according to Pure Earth. When you turn on a Geiger counter, you'll usually hear some clicks right away, no matter where you are, according to the NRC.

That's because of naturally occurring background radioactivity that comes from the sun, natural uranium in the soil, certain types of rock, and radon , a naturally occurring radioactive gas, among other sources.

There is a central electrode inside the GM tube. A high voltage supply is connected across the casing of the tube and the central electrode as shown in the following diagram.

When alpha, beta or gamma radiation enters the tube it produces ions in the gas. The ions created in the gas enable the tube to conduct.

A current is produced in the tube for a short time. The current produces a voltage pulse. Each voltage pulse corresponds to one ionising radiation entering the GM tube. The voltage pulse is amplified and counted. The greater the level of radiation, the more ionisation in the tube so the greater the number of counts. This causes the temporary closing of a switch and generates an electric pulse that is registered on a meter, either acoustically as a click that increases in intensity as the ionizing radiation increases, or visually as the motion of a needle pointer.

Radioactivity can be measured in order to discover the amount of radiation a material emits or the amount of radiation absorbed by a human or mammal. The unit for measuring radioactive emissions is the becquerel Bq. The Bq indicates the number of decays per second.