What are Gamma Rays?
Gamma rays are the most energetic form of light, highly penetrating electromagnetic energy emitted by the nucleus of some radionuclides following radioactive decay.The discovery of gamma rays is attributed to a French physicist Henri Becquerel in 1896.
A British physicist Ernest Rutherford coined the term gamma ray in 1903 following former studies of the emissions of radioactive nuclei. These rays don’t carry an electric charge; they can penetrate enormous distances through materials before interacting with several centimeters of lead or a meter of concrete required to halt the gamma rays.
The Greek symbol for gamma rays is γ (Gamma).
How are Gamma Rays Produced?
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Gamma rays are generated in the decomposition of radioactive atomic nuclei and in the decay of definite subatomic particles. These powerful rays are part of the electromagnetic spectrum, produced by the hottest and most energetic objects in the universe.
The universal objects such as neutrons, stars, pulsars, regions circa black holes and supernova explosions.
On Earth, gamma rays are produced by the emissions caused in various objects, namely:
Nuclear explosions.
Lightning.
Activity of radioactive decay.
Nuclear reactions such as fusion, fission, alpha decay and gamma decay.
Nuclear fusion is a reaction that powers the sun and stars.
Frequency Range of Gamma Rays
Gamma rays are the electromagnetic waves of frequency range as given below:
Unit of Gamma Ray
Gamma rays are generally measured in API units where API stands for American petroleum institute.
API is the unit for radioactivity which is used for measuring the natural gamma rays in ground.
Gamma Rays Wavelength
A highly energetic electromagnetic radiation, having an energy greater than 100 Kilo electronVolt or keV and frequencies greater than1019 Hz.
It has the smallest wavelength less than 10 picometer which is a very low value which means they cannot be seen or felt.
Application of Gamma Rays
Gamma rays are used in a range of aspects in our real lives:
We use them in the treatment of cancers to kill carcinogenic cells and prevent them from growing.
To treat tumors.
We use them for preserving the foodstuffs for a long time as the soft gamma rays can kill microorganisms easily.
To produce nuclear reactions.
To provide valuable information about the structure of an atomic nucleus.
In industry, gamma rays are used to check the oil pipeline and detect its weak points.
In the field of medicines, gamma rays are used for radiotherapy and sterilizing medical equipment.
Flaw orientation: In engineering, gamma rays see a crack as a thickness variation and larger the variation, easier the crack is to detect. Other things that gamma rays can detect are: Weld defect, density change, and non-uniformity of the material.
In astronomy, to look for distant gamma-ray sources.
Used for sterilization and disinfection.
The field of science: Gamma rays are used in the development of nuclear reactors and bombs.
How are Gamma Rays Used in Medicine?
Gamma rays can kill any living organism. It is used as an advantage in the field of medical, especially oncology.
For treating cancer
These rays are used to treat cancer patients. High doses of gamma rays are passed to kill the cancerous cells in a process called radiotherapy. Under this process, a beam of gamma ray is focused to kill the DNA of cancerous cells. These high-energy rays ionize water in the cancerous cell, producing free radicals of H and OH.
The free radicals are highly reactive, and they interact and harm chromosomes in the cell. The primary focus of the radiation oncologist is to concentrate the beam of radiation to the cancer as much as possible to avoid side effects.
They are used for treating tumors where a high-energy photon is transmitted to the targeted tumor so that these rays don’t affect the surrounding tissues.
An intensive care is taken to treat cancer and tumor patients.
Sterilizing medical equipment
Gamma rays easily pass through the packaging of medical equipment and kill living tissues such as viruses and bacteria.
Advantages of Gamma Rays
There are various advantages of gamma rays discussed below:
High penetrating power
Portable (mobile sources)
Less scattering
Easily accessible
Easily available resources
High energy and resolution
Affordable
Helpful for searching super symmetric dark matter particles in the milky way.
Used by scientists to determine the elements on other planets.
Suitable for field inspection.
X Rays and Gamma Rays
Gamma rays and X-rays are both high energy, high frequency electromagnetic radiations.
They both are massless packets of energy and both carry no charge.
The biggest difference between them is that gamma rays are used for photons from naturally occurring sources while X-rays are used for photons from man-made machines.
Gamma rays arise due to transitions between nuclear energy levels whereas X-rays arise due to transitions of electrons between electronic energy levels.
Gamma rays are with discrete energies and X-rays are with both discrete and continuous energies.
FAQs on Gamma Rays - Electromagnetic Spectrum
1. What are gamma rays and where do they fit in the electromagnetic spectrum?
Gamma rays (γ) are a form of highly energetic electromagnetic radiation. Within the electromagnetic spectrum, they hold the position of having the highest energy, the highest frequency (greater than 1019 Hz), and the shortest wavelength (less than 10 picometres). They are produced by the most energetic events in the universe and by radioactive decay on Earth.
2. What are the key properties of gamma rays?
Gamma rays have several distinct properties based on their position in the electromagnetic spectrum. Key properties include:
- High Penetrating Power: They can pass through many materials, including skin and paper, and require dense materials like lead or concrete to be stopped.
- No Electric Charge: As photons, they are electrically neutral and are not deflected by electric or magnetic fields.
- High Energy and Frequency: They are the most energetic waves in the EM spectrum.
- Travel at the Speed of Light: Like all electromagnetic radiation, they travel at approximately 3 x 108 m/s in a vacuum.
- Ionising Radiation: They have enough energy to knock electrons out of atoms, which can damage living tissue.
3. What are the most common applications of gamma rays?
Despite their potential hazards, gamma rays have several important real-world applications across different fields:
- Medicine: Used in a procedure called radiotherapy (or Gamma Knife surgery) to target and destroy cancerous cells and tumours. They are also used to sterilise medical equipment by killing viruses and bacteria.
- Industry: Used to inspect metal castings and welds for flaws or cracks, similar to how X-rays are used. They are also used to check oil pipelines for weak points.
- Food Preservation: Low doses of gamma rays can kill microorganisms like bacteria and mould, extending the shelf life of foodstuffs.
- Scientific Research: Used in astronomy to study high-energy phenomena like supernovae and black holes, and in nuclear physics to understand the structure of atomic nuclei.
4. How are gamma rays different from X-rays?
The primary difference between gamma rays and X-rays lies in their origin. Although both are high-energy photons, gamma rays are produced from transitions within an atomic nucleus, typically during radioactive decay. In contrast, X-rays are generated by the transitions of high-energy electrons outside the nucleus. Essentially, gamma rays originate from nuclear processes, while X-rays originate from electronic processes.
5. What are the main sources of gamma radiation?
Gamma rays are generated from both natural and man-made sources. Natural sources include the radioactive decay of elements in the Earth's crust (like cobalt-60 and caesium-137), lightning strikes, and cosmic events like supernovae and pulsars. Man-made sources include nuclear explosions, nuclear fission reactors, and particle accelerators.
6. How can gamma rays, which are harmful, be used safely to treat cancer?
The use of gamma rays in cancer treatment is based on the principle of targeted radiation. In radiotherapy, multiple highly focused beams of gamma rays are directed at a tumour from various angles. While each individual beam is too weak to cause significant harm to the healthy tissue it passes through, the beams converge at the location of the tumour. At this focal point, the combined energy is high enough to destroy the DNA of cancer cells, preventing them from replicating, while minimising damage to the surrounding healthy cells.
7. Why do gamma rays have such high penetrating power?
Gamma rays have exceptional penetrating power because they are electrically neutral photons with very high energy. Unlike charged particles (like alpha or beta particles), they do not interact with matter through electrostatic forces. This lack of charge allows them to travel significant distances through materials before a direct collision with an atomic nucleus or electron occurs. To effectively stop them, a dense material with a high number of electrons, such as lead, is required to increase the probability of such an interaction.
8. What type of shielding is required to protect against gamma radiation?
Due to their high energy and penetrating ability, stopping gamma rays requires significant shielding. The most effective materials are those with a high atomic number and high density. Common shielding materials include thick slabs of lead or several feet of concrete or packed soil. The effectiveness of a shield is determined by its thickness and density, as these factors increase the chance of a gamma photon interacting with the material and losing its energy.
