Three Types of Radiation: The Properties and Uses of Alpha, Beta, and Gamma Radiation
Properties of Alpha, Beta, and Gamma Radiation: Relative Strength
Properties of Alpha, Beta, and Gamma Radiation: Speed and Energy
Relative Ionising ability
High (varies hugely)
close to speed of light
Very high (again, varies hugely)
What are the Three Types of Radiation?
When atoms decay, they emit three types of radiation, alpha, beta and gamma. The alpha and beta radiation consist of actual matter that shoots off the atom, while gamma rays are electromagnetic waves. All three kinds of radiation are potentially hazardous to living tissue, but some more than others, as will be explained later on.
Properties of Alpha Radiation
The first type of radiation, Alpha, consists of two neutrons and two protons bound together to the nucleus of a Helium atom. Though the least powerful of the three types of radiation, alpha particles are nonetheless the most densely ionizing of the three. That means when alpha rays can cause mutations in any living tissue they come into contact with, potentially causing unusual chemical reactions in the cell and possible cancer.
They are still viewed as the least dangerous form of radiation, as long as it's not ingested or inhaled, because it can be stopped by even a thin sheet of paper or even skin, meaning that it cannot enter the body very easily.
A case of alpha radiation poisoning made international news a few years ago when Russian dissident Alexander Litvinenko was believed to have been poisoned with it by the Russian spy service.
Uses of Alpha Radiation
Alpha particles are most commonly used in smoke alarms. These alarms contain a tiny amount of decaying Americium between two sheets of metal. The decaying Americium emits alpha radiation. A small electric current is then passed through one of the sheets and into the second one.
When the field of alpha radiation is blocked by smoke, the alarm goes off. This alpha radiation is not harmful because it is very localised and any radiation that might escape would be stopped quickly in the air and would be extremely difficult to get into your body.
Properties of Beta Radiation
Beta radiation consists of an electron and is characterized by its high energy and speed. Beta radiation is more hazardous because, like alpha radiation, it can cause ionisation of living cells. Unlike alpha radiation, though, beta radiation has the capacity to pass through living cells, though it can be stopped by an aluminum sheet. A particle of beta radiation can cause spontaneous mutation and cancer when it comes into contact with DNA.
Uses of Beta Radiation
Beta radiation is mainly used in industrial processes such as paper mills and aluminium foil production. A beta radiation source is placed above the sheets coming out of the machines while a Geiger counter, or radiation reader, is placed underneath. The purpose of this is to test the thickness of the sheets. Because the beta radiation can only partially penetrate aluminium foil, if the readings on the Geiger counter are too low, it means that the aluminium foil is too thick and that the presses are adjusted to make the sheets thinner. Likewise, if the Geiger reading is too high, the presses are adjusted to make the sheets thicker.
Sidenote: The blue glow produced in some nuclear power plant pools is due to high speed beta particles moving faster than that of light traveling through water. This can occur because light travels at roughly 75% its typical speed when in water and beta radiation can, therefore, exceed this speed without breaking the speed of light.
Properties of Gamma Radiation
Gamma rays are high frequency, extremely-short-wavelength electromagnetic waves with no mass and no charge. They are emitted by a decaying nucleus, that expels the gamma rays in an effort to become more stable as an atom.
Gamma rays have the most energy and can penetrate substances up to a few centimetres of lead or a few metres of concrete. Even with such intense barriers, some radiation may still get through because of how small the rays are. Though the least ionising of all the forms of radiation, that doesn't mean Gamma rays aren't dangerous. They are likely to be emitted alongside alpha and beta radiation, though some isotopes emit gamma radiation exclusively.
Uses of Gamma Radiation
Gamma rays are the most useful type of radiation because they can kill off living cells easily, without lingering there. They are therefore often used to fight cancer and to sterilise food, and kinds of medical equipment that would either melt or become compromised by bleaches and other disinfectants.
Gamma rays are also used to detect leaking pipes. In those situations, a gamma ray source is placed into the substance flowing through the pipe. Then, someone with a Geiger-Muller tube above-ground will measure the radiation given off. The leak will be identified wherever the count on the Geiger-Muller tube spikes, indicating a large presence of gamma radiation coming out of the pipes.
Uses of Alpha, Beta, and Gamma Radiation: Radiocarbon Dating
Radiocarbon dating is used to determine the age of once-living tissue, including objects like string, rope, and boats, all of which were made from living tissue.
The radioactive isotope measured in carbon dating is carbon-14, which is produced when cosmic rays act on nitrogen in the upper atmosphere. Only one in every 850,000,000 carbon atoms are carbon-14, but they are easily detected. All living cells take up carbon-14, whether from photosynthesis or eating other living cells. When a living cell dies, it stops taking in carbon-14, because it stops photosynthesising or eating, and then gradually over time the carbon-14 decays and is no longer found in the tissue.
Carbon-14 emits beta particles and gamma rays. The half-life of carbon-14 (the time in which it takes from the radiation emitted from the source to be halved) works out to be 5,730 years. This means that if we find tissue that has 25% of the amount of carbon-14 found in today’s atmosphere, we can determine the object is 11,460 years old because 25% is half and half again, meaning that the object has experienced two half lives.
There are, of course, limitations and inaccuracies to carbon dating. For example we make the assumption that the amount of carbon-14 in the atmosphere back when the tissue was living, is the same as nowadays.
I hope this article has helped you understand nuclear radiation. If you have any questions, suggestions or issues please leave a comment below (no sign up required) and I will try to answer it either on the comments section or update the article to incorporate it!