August 20, 2014

Gamma Rays- Formation, Properties, Their difference with X Rays and Applications - Explained

Discovered by - Paul Villard, a French physicist,  is credited with discovering gamma rays. He had discovered they were emitted from radioactive substances and were not affected by electric or magnetic fields.Named as “Gamma rays” three years later by Ernest Rutherford.
-Gamma Rays - are electromagnetic rays like X rays and travel with speed of light. Electromagnetic radiation can be described in terms of a stream of photons, which are mass less particles each travelling in a wave-like pattern and moving at the speed of light. Each photon contains a certain amount (or bundle) of energy, and all electromagnetic radiation consists of these photons.
 -Gamma-ray photons have the highest energy in the EMR spectrum and their waves have the shortest wavelength. Their high frequency makes them more penetrating compared to X Rays.

Key differences between Gamma Rays  and X Rays is where from they Originate:
  • Gamma rays originate in the radioactive nucleus after radioactive decay. It often follows the emission of a beta particle or Alpha Particle.
  • X-rays originate in the electron fields surrounding the nucleus or are machine-produced.( X-rays are produced when electrons strike a target or when electrons are rearranged within an atom)

Properties of Gamma Rays:
(1) They are photons, like light, thus they are neutral.
(2) It is the lightest among the three; since it does not carry any charges /proton /neutron/ electron.
(3) Gamma rays has the highest penetrating power, as it does not diffract well in the air.
(4) They can penetrate at a larger area; and can be stopped by a thick lead block.
(5) Gamma rays have almost no ionizing power, as they carry no charges.
(6) Gamma rays travel at the speed of light.
(7) Gamma radiation or X-rays frequently accompany the emission of alpha and beta radiation.
(8) Gamma radiation is very high-energy ionizing radiation. Though x-rays are also ionizing radiation, because of the lower energy compared to gamma rays, they may fail to reach sufficiently deep into the body and may cause instead damage to the surrounding tissues that absorbed them.

Production of Gamma Rays:
There are several physical processes that generate gamma rays they are:
  1. A high-energy particle can collide with another particle
  2. A particle can collide and annihilate with its anti-particle
  3. An element can undergo radioactive decay
  4. Accelerate the a particle by magnetic field. This causes the particle to radiate
Gamma rays can be produced in labs through the process of nuclear collision and also through the artificial radioactivity that accompanies these interactions. The high-energy nuclei needed for the collisions are accelerated by devices such as the cyclotron and synchrotron. 

What is ionization? How this property becomes harmful for Gamma Rays Applications?
When they pass through matter, they eject electrons from the atoms they collide with. This is called ionization, and it's dangerous to living cells; prolonged gamma radiation can lead to grave illness and even death.

Applications of Gamma Rays- Uses of Gamma Emitting Radio-nuclides:

Uses of Cesium-137:
  • cancer treatment
  • measure and control the flow of liquids in numerous industrial processes
  • investigate subterranean strata in oil wells
  • measure soil density at construction sites
  • ensure the proper fill level for packages of food, drugs and other products.
Uses of Cobalt-60:
  • sterilize medical equipment in hospitals
  • pasteurize certain foods and spices
  • treat cancer
  • gauge the thickness of metal in steel mills.
Uses of Technetium-99m:
  • TC-99m is the most widely used radioactive isotope for diagnostic studies. (Technetium-99m is a shorter half-life precursor of technetium-99.) Different chemical forms are used for brain, bone, liver, spleen and kidney imaging and also for blood flow studies.
Uses of Americium-241:
  • fluid-level gauges
  • fluid-density gauges
  • thickness gauges
  • aircraft fuel gauges
  • distance-sensing devices, all of which utilize its gamma radiation.
Note: Most people's primary source of gamma exposure is naturally occurring radio-nuclides, particularly potassium-40, which is found in soil and water, as well as meats and high-potassium foods such as bananas. 
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