Nuclear Radiation: Radioactive Decay

Nuclear Radiation: Radioactive Decay Overview

  • Radioactive decay is a process in which an unstable atomic nucleus loses energy by emitting ionising particles or radiation.
  • This process is random and spontaneous, meaning it can happen at any time, without being induced by outside factors.
  • The types of radioactive decay include alpha, beta, and gamma decay.

Alpha Decay

  • Alpha decay involves the ejection of an alpha particle from the nucleus, decreasing the atomic number by 2 and the mass number by 4.
  • An alpha particle is equivalent to a helium-4 nucleus, composed of two protons and two neutrons.
  • This type of decay commonly occurs in large, heavy elements, such as uranium and radium.

Beta Decay

  • Beta decay involves the transformation of a neutron into a proton, ejecting an electron (beta-minus decay) or positron (beta-plus decay) in the process.
  • In beta-minus decay, the atomic number increases by 1, while it decreases by 1 in beta-plus decay. The mass number remains unchanged in both cases.
  • This type of decay often occurs in neutron-rich or neutron-deficient isotopes.

Gamma Decay

  • Gamma decay is the emission of gamma rays, which are high-energy photons.
  • This occurs when an excited nucleus returns to its ground state. During this process, no change occurs in the atomic number or mass number.
  • Gamma rays are highly penetrating electromagnetic waves, capable of causing ionisation.

Half-Life

  • The half-life of a radioactive substance is the time taken for half of the atoms in a radioactive sample to decay.
  • It’s important to note that each radioactive isotope has its own unique half-life, irrespective of the physical or chemical form in which the isotope appears.
  • The concept of half-life can be used to date archaeological artifacts and geological samples, as well as in medical applications.

Safety and Protection against Nuclear Radiation

  • Exposure to high levels of nuclear radiation can be harmful, hence protection measures are required.
  • Protection methods include a combination of time (reducing time spent near the source), distance (increasing the distance from the source), and shielding (using barriers of lead or concrete).
  • Radiation levels are measured using devices such as Geiger-Muller counters and dosimeters.

Applications of Nuclear Radiation

  • Nuclear radiation plays a significant role in medicine for both diagnosis (e.g., PET scans) and treatment (e.g., radiotherapy for cancer).
  • It’s used in industry for purposes like testing for leaks, gauging thickness of materials, and sterilisation.
  • In research, nuclear radiation is used for tracing, dating artefacts, and in nuclear reactor technology.