Sunday, July 17, 2011
When the nucleus of an atom decays, it ejects one or more types of the following radiation: Alpha particles (α) are composed of two protons and two neutrons, or a “helium nucleus”. Alpha radiation can be easily stopped by your skin or a piece of paper; however it has the highest ionizing power and if it gets inside you, is least likely to escape. Beta particles (β) can be split into normal β- and β+ particles. When a neutron decays into a proton, a β- particle, or an electron is emitted (because a neutron is made out of a positive and negative charge). In the same decay process, along with the β- comes an “electron anti-neutrino” — a particle with negligible mass; theoretically conceived to balance decay reactions. (It was experimentally found some years later.) On the other hand, β+ radiation happens when a proton decays into a neutron, by emitting a positron (the anti-particle of an electron, which has a positive charge) and an electron neutrino. β particles are easily stopped by a sheet of aluminium. Gamma radiation (γ) is a form of energy, and thus has neither mass nor charge. It also has the shortest wavelength in the EM (electro-magnetic) wave spectrum. It has the highest penetrating power, and is really only slowed down significantly by many centimeters of lead. γ radiation cannot originate from a nucleus that doesn’t spontaneously emit some other type of radiation. Most atoms have a stable nucleus that doesn’t change; however, a radioactive substance has a nucleus that is unstable. To stabilize itself, the nucleus emits radiation. Radioactive decay is a spontaneous process that cannot be controlled and is not affected by temperature; however, each radioactive element has its own particular decay rate, also known as its half-life. The half-life of a radioactive element is the time that it takes half the atoms in the sample to decay or for the count rate to decay to half.

When the nucleus of an atom decays, it ejects one or more types of the following radiation:

  1. Alpha particles (α) are composed of two protons and two neutrons, or a “helium nucleus”. Alpha radiation can be easily stopped by your skin or a piece of paper; however it has the highest ionizing power and if it gets inside you, is least likely to escape.
  2. Beta particles (β) can be split into normal β- and β+ particles. When a neutron decays into a proton, a β- particle, or an electron is emitted (because a neutron is made out of a positive and negative charge). In the same decay process, along with the β- comes an “electron anti-neutrino” — a particle with negligible mass; theoretically conceived to balance decay reactions. (It was experimentally found some years later.) On the other hand, β+ radiation happens when a proton decays into a neutron, by emitting a positron (the anti-particle of an electron, which has a positive charge) and an electron neutrino. β particles are easily stopped by a sheet of aluminium.
  3. Gamma radiation (γ) is a form of energy, and thus has neither mass nor charge. It also has the shortest wavelength in the EM (electro-magnetic) wave spectrum. It has the highest penetrating power, and is really only slowed down significantly by many centimeters of lead. γ radiation cannot originate from a nucleus that doesn’t spontaneously emit some other type of radiation.

Most atoms have a stable nucleus that doesn’t change; however, a radioactive substance has a nucleus that is unstable. To stabilize itself, the nucleus emits radiation.

Radioactive decay is a spontaneous process that cannot be controlled and is not affected by temperature; however, each radioactive element has its own particular decay rate, also known as its half-life. The half-life of a radioactive element is the time that it takes half the atoms in the sample to decay or for the count rate to decay to half.

Posted at 3:24 PM 35 notes Tags: alpha beta electron element gamma half-life helium negligible neutron physics positron proton radiation science sayitwithscience information education

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