How does a geiger muller tube detect radiation

The ionising effect of radiation is used in the Geiger-Muller GM tube as a means of detecting the radiation. The GM tube is a hollow cylinder filled with a gas at low pressure. The tube has a thin window made of mica at one end.

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. When ionisation occurs, a positively-charged argon ion and a negatively-charged electron are produced. The argon ion is attracted to the outside wall of the tube, which is connected to the negative terminal of the power supply, while the electron is attracted to the central electrode, which is kept at a high positive voltage — typically V.

A small pulse of current is produced each time an electron reaches the central electrode. These pulses can be counted by an electronic circuit and a displayed on an LCD display. Sometimes a small speaker is added to the system to produce a click for each pulse.

Workers in the nuclear industry wear "film badges" which are sent to a laboratory to be developed, just like your photographs.

This allows us to measure the dose that each worker has received usually each month. The badges have "windows" made of different materials, so that we can see how much of the radiation was alpha particles, or beta particles, or gamma rays.

Dry air is normally a good insulator, so a charged electroscope will stay that way, as the charge cannot escape. When an electroscope is charged, the gold leaf sticks out, because the charges on the gold repel the charges on the metal stalk. When a radioactive source comes near , the air is ionised, and starts to conduct electricity.

This means that the charge can "leak" away, the electroscope discharges and the gold leaf falls. An early form of detector, the Spark Counter is another instrument that uses the ionising effect of radioactivity, and for this reason it works best with particles. A high voltage is applied between the gauze and the wire, and adjusted until it is just below the voltage required to produce sparks.

When a radioactive source is brought near , the air between the gauze and the wire is ionised , and sparks jump where particles pass. There are two types of cloud chamber: the "expansion" type and the "diffusion" type.

In both types, alpha or beta particles leave trails in the vapour in the chamber, rather like high-altitude aircraft leave trails in the sky. Appears in these Collections Curated Collection Counting ions and ionisation These demonstrations show different ways of detecting and counting ionisation. Ready To Teach Collection Teaching radioactivity The purpose of this collection of resources is to support the teaching of ionizing Ionising Radiation Quantum and Nuclear.

How to make an infrared transmitter. Misconceptions Quantum and Nuclear Many students are confused by the nature of radiation in general and some think it is artificial Number of Resources 0 Number of References 1 Number of Diagnostic Resources 1. Quantum and Nuclear Many students are aware that radiation can cause cancer but few are aware of beneficial uses Number of Resources 0 Number of References 1 Number of Diagnostic Resources 0.

Quantum and Nuclear Some students think that ionising radiation only stems from nuclear power plants Number of Resources 0 Number of References 1 Number of Diagnostic Resources 0.