[Physics Class Notes] on Gamma Rays – Electromagnetic Spectrum Pdf for Exam

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?

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:

1.  Nuclear explosions.

2.  Lightning.

3. Activity of radioactive decay.

4. Nuclear reactions such as fusion, fission, alpha decay and gamma decay.

5. 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:

1. We use them in the treatment of cancers to kill carcinogenic cells and prevent them from growing. 

2. To treat tumors.

3. We use them for preserving the foodstuffs for a long time as the soft gamma rays can kill microorganisms easily.

4. To produce nuclear reactions.

5. To provide valuable information about the structure of an atomic nucleus.

6. In industry, gamma rays are used to check the oil pipeline and detect its weak points.

7. In the field of medicines, gamma rays are used for radiotherapy and sterilizing medical equipment.

8. 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.

9. In astronomy, to look for distant gamma-ray sources.

10.  Used for sterilization and disinfection.

11. 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.

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:

1. High penetrating power

2. Portable (mobile sources)

3. Less scattering

4. Easily accessible

5. Easily available resources

6. High energy and resolution

7. Affordable

8. Helpful for searching super symmetric dark matter particles in the milky way.

9. Used by scientists to determine the elements on other planets.

10.  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.