Geiger counters use the natural process of ionization to detect and measure radiation levels.

A Geiger counter, also known as a Geiger-Muller tube, is an inexpensive and useful instrument used to quickly detect and measure radiation.

There are two types of radiation, non-ionizing and ionizing. Non-ionizing radiation, such as microwaves, has enough energy to shake up atoms, but not enough to knock off their electrons and change their composition.

On the other hand, ionizing radiation can strip atoms of their electrons, in a process called ionization. As a result, an ion pair is formed – a positively charged atom and a negatively charged electron. A Geiger counter exploits the natural process of ionization to detect and measure radiation. The device houses a stable gas inside its chamber.

When exposed to radioactive particles, this gas ionizes. This generates an electric current that the meter registers over a period of 60 seconds.

A cheap and useful tool

There are several different types of radioactive particles that cause ionization, known as alpha, beta, or gamma radiation. However, Geiger counters cannot differentiate between different types of radiation.

Exposure to ionizing radiation can be harmful to human health. When this type of radiation comes into contact with DNA molecules in living cells, its energetic nature can disrupt, damage, or alter the DNA. Short-term exposure to some forms of radiation, such as X-rays for medical examinations, does not cause immediate health risks.

However, prolonged exposure can lead to DNA mutations and cause cancers. So Geiger counters are an invaluable tool for evaluating a potential source of radioactivity

Types of ionizing radiation

Alpha radiation particles contain two protons and two neutrons, like the nucleus of a helium atom. They are heavy and slow moving and can be blocked by a piece of paper or a thin layer of skin. This makes them significantly less dangerous than other types of radiation.

Beta radiation particles are high energy electrons. These are relatively light particles, about one-thousandth the mass of a proton. Natural sources of beta radiation are elements that decay radioactively, such as uranium or actinium.

Gamma rays, also called gamma rays, are a form of electromagnetic radiation similar to X-rays. They emit photons (particles of electromagnetic radiation) with the highest energy in the electromagnetic spectrum. Gamma rays are very penetrating and can easily pass through the body to cause damage.

How was the Geiger counter created?

The Geiger counter was conceptualized and designed by German physicists Hans Wilhelm Gieger and British physicist Ernest Rutherford in 1908. Their original creation could only detect alpha particles.

The two used their counter to study alpha particles and in 1911 published the results of several groundbreaking experiments, such as the gold foil experiment, which finally revealed the nucleus of atoms to the world.

Between 1925 and 1928, Geiger and his doctoral student Walter Muller improved the counter’s sensitivity to detect all types of ionizing radiation.

The design of the Gieger-Muller counter has remained relatively unchanged in the Gieger counters in use today, he writes LiveScience.

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