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Alpha Particles
Certain radionuclides of high atomic mass (Ra226, U238, Pu239) decay by the emission of alpha particles. These alpha particles are tightly bound units of two neutrons and two protons each (He4 nucleus) and have a positive charge. Emission of an alpha particle from the nucleus results in a decrease of two units of atomic number (Z) and four units of mass number (A). Alpha particles are emitted with discrete energies characteristic of the particular transformation from which they originate. All alpha particles from a particular radionuclide transformation will have identical energies.
Beta Particles
A nucleus with an unstable ratio of neutrons to protons may decay through the emission of a high speed electron called a beta particle. This results in a net change of one unit of atomic number (Z). Beta particles have a negative charge and the beta particles emitted by a specific radionuclide will range in energy from near zero up to a maximum value, which is characteristic of the particular transformation.
Gamma-rays
A nucleus which is in an excited state may emit one or more photons (packets of electromagnetic radiation) of discrete energies. The emission of gamma rays does not alter the number of protons or neutrons in the nucleus but instead has the effect of moving the nucleus from a higher to a lower energy state (unstable to stable). Gamma ray emission frequently follows beta decay, alpha decay, and other nuclear decay processes.
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The ability of radioactivity to pass through materials is called its penetrating ability.It depends on the size of the radioactive particle.a-particles are the biggest,b-particles are very much smaller and g-rays have no mass.The bigger the particle,the more likely it is to collide with the atoms of the material.The collision will stop the particle going through the material.a-particles are the biggest and are least able to penetrate a material.Paper will stop them and even in air a-particles only travel for a few centimetres before they are stopped.b-particles are stopped by a few millimetres of aluminium.g-rays are able to penetrate the most and will even find their way through metres of concrete.
Certain radionuclides of high atomic mass (Ra226, U238, Pu239) decay by the emission of alpha particles. These alpha particles are tightly bound units of two neutrons and two protons each (He4 nucleus) and have a positive charge. Emission of an alpha particle from the nucleus results in a decrease of two units of atomic number (Z) and four units of mass number (A). Alpha particles are emitted with discrete energies characteristic of the particular transformation from which they originate. All alpha particles from a particular radionuclide transformation will have identical energies.
Beta Particles
A nucleus with an unstable ratio of neutrons to protons may decay through the emission of a high speed electron called a beta particle. This results in a net change of one unit of atomic number (Z). Beta particles have a negative charge and the beta particles emitted by a specific radionuclide will range in energy from near zero up to a maximum value, which is characteristic of the particular transformation.
Gamma-rays
A nucleus which is in an excited state may emit one or more photons (packets of electromagnetic radiation) of discrete energies. The emission of gamma rays does not alter the number of protons or neutrons in the nucleus but instead has the effect of moving the nucleus from a higher to a lower energy state (unstable to stable). Gamma ray emission frequently follows beta decay, alpha decay, and other nuclear decay processes.
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The ability of radioactivity to pass through materials is called its penetrating ability.It depends on the size of the radioactive particle.a-particles are the biggest,b-particles are very much smaller and g-rays have no mass.The bigger the particle,the more likely it is to collide with the atoms of the material.The collision will stop the particle going through the material.a-particles are the biggest and are least able to penetrate a material.Paper will stop them and even in air a-particles only travel for a few centimetres before they are stopped.b-particles are stopped by a few millimetres of aluminium.g-rays are able to penetrate the most and will even find their way through metres of concrete.
