Alpha, Beta and Gamma Radiation

Alpha, Beta and Gamma Radiation

Alpha Particles

Alpha Particle - Interaction with MatterAlpha particles are energetic nuclei of helium. The production of alpha particles is termed alpha decay. Alpha particles consist of two protons and two neutrons bound together into a particle identical to a helium nucleus. Alpha particles are relatively large and carry a double positive charge. They are not very penetrating and a piece of paper can stop them. They travel only a few centimeters but deposit all their energies along their short paths.

In nuclear reactors they are produced for example in the fuel (alpha decay of heavy nuclei). Alpha particles are commonly emitted by all of the heavy radioactive nuclei occuring in the nature (uranium, thorium or radium), as well as the transuranic elements (neptunium, plutonium or americium).

Especially energetic alpha particles (except artificially accelerated helium nuclei) are produced in a nuclear process, which is known as a ternary fission. In this process, the nucleus of uranium is splitted into three charged particles (fission fragments) instead of the normal two. The smallest of the fission fragments most probably (90% probability) being an extra energetic alpha particle.

See also: Alpha Particle

See also: Interaction of Heavy Particles with Matter

See also: Shielding of Alpha Particles

Alpha Particle - Cloud Chamber
Alpha particles and electrons (deflected by a magnetic field) from a thorium rod in a cloud chamber.

Beta Particles

Description Beta Particles

Beta particles are high-energy, high-speed electrons or positrons emitted by certain fission fragments or by certain primordial radioactive nuclei such as potassium-40. The beta particles are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay. There are two forms of beta decay, the electron decay (β− decay) and the positron decay (β+ decay). In a nuclear reactor occurs especially the β− decay, because the common feature of the fission products is an excess of neutrons (see Nuclear Stability). An unstable fission fragment with the excess of neutrons undergoes β− decay, where the neutron is converted into a proton, an electron, and an electron antineutrino.

See also: Beta Particle

See also: Interaction of Beta Particles with Matter

See also: Shielding of Beta Radiation

beta decay
Beta decay of C-14 nucleus.
β- particles
β- particles (electrons) are energetic electrons. The electrons are negatively charged, almost massless particles that nevertheless account for most of the size of the atom. Electrons were discovered by Sir John Joseph Thomson in 1897. Electrons are located in an electron cloud, which is the area surrounding the nucleus of the atom. The electron is only one member of a class of elementary particles, which forms an atom.
β+ particles
β+ particles (positrons) are antiparticles of negative electrons. Positrons, also called positive electrons,  have a positive electric charge and have the same mass and magnitude of charge as the electrons. An annihilation occurs, when a low-energy positron collides with a low-energy electron.

Gamma Rays

Gamma rays, also known as gamma radiation, refers to electromagnetic radiation (no rest mass, no charge) of a very high energies. Gamma rays are high-energy photons with very short wavelengths and thus very high frequency. Since the gamma rays are in substance only a very high-energy photons, they are very penetrating matter and are thus biologically hazardous. Gamma rays can travel thousands of feet in air and can easily pass through the human body.

Gamma rays are emitted by unstable nuclei in their transition from a high energy state to a lower state known as gamma decay. In most practical laboratory sources, the excited nuclear states are created in the decay of a parent radionuclide, therefore a gamma decay typically accompanies other forms of decay, such as alpha or beta decay.

Radiation and also gamma rays are all around us. In, around, and above the world we live in. It is a part of our natural world that has been here since the birth of our planet. Natural sources of gamma rays on Earth are inter alia gamma rays from naturally occurring radionuclides, particularly potassium-40.  Potasium-40 is a radioactive isotope of potassium which has a very long half-life of 1.251×109 years (comparable to the age of Earth). This isotope can be found in soil, water also in meat and bananas. This is not the only example of natural source of gamma rays.

See also: Gamma Rays

See also: Interaction of Gamma Radiation with Matter

See also: Shielding of Gamma Radiation

A photon, the quantum of electromagnetic radiation,  is an elementary particle, which is the force carrier of the electromagnetic force. The modern photon concept was developed (1905) by Albert Einstein to explain of the photoelectric effect, in which he proposed the existence of discrete energy packets during the transmission of light.Before Albert Einstein, notably the German physicist Max Planck had prepared the way for the concept by explaining that objects that emit and absorb light do so only in amounts of energy that are quantized, that means every change of energy can occur only by certain particular discrete amounts and the object cannot change energy in any arbitrary way. The concept of modern photon came into general use after the physicist Arthur H. Compton demonstrated (1923) the corpuscular nature of X-rays. This was the validation that  Einstein’s hypothesis that light itself is quantized.The term photon comes from Greek phōtos, “light” and a photon is usually denoted by the symbol γ (gamma). The photons are also symbolized by hν (in chemistry and optical engineering), where h is Planck’s constant and the Greek letter ν (nu) is the photon’s frequency. The radiation frequency is key parameter of all photons, because it determines the energy of a photon. Photons are categorized according to the energies from low-energy radio waves and infrared radiation, through visible light, to high-energy X-rays and gamma rays.Photons are gauge bosons for electromagnetism, having no electric charge or rest mass and one unit of spin. Common to all photons is the speed of light, the universal constant of physics. In empty space, the photon moves at c (the speed of light – 299 792 458 metres per second).
Barium-137m is a product of a common fission product - Caesium - 137. The main gamma ray of Barium-137m is 661keV photon.
Barium-137m is a product of a common fission product – Caesium – 137. The main gamma ray of Barium-137m is 661keV photon.

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