Beta particles

Beta Particles

Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei, such as potassium-40. The production of beta particles is termed beta decay.

Types of Beta Decay

Beta decay is a type of radioactive decay in which a beta particle is emitted from an atomic nucleus. There are two types of beta decay:

• Beta-minus (β⁻) decay: In this process, a neutron is converted into a proton, an electron (the beta particle), and an antineutrino. This can be represented by the equation:

 : n → p + e⁻ + \bar{ν}_e

• Beta-plus (β⁺) decay: In this process, a proton is converted into a neutron, a positron (the beta particle), and a neutrino. This can be represented by the equation:

 : p → n + e⁺ + ν_e

Properties of Beta Particles

Beta particles are much lighter than alpha particles and have a greater penetration power. They can travel several meters in air and can penetrate human skin, but they are generally stopped by a few millimeters of plastic or a few centimeters of glass or metal.

Energy and Speed

The energy of beta particles can vary widely, typically from a few keV to several MeV. Their speed can approach that of light, depending on their energy.

Interaction with Matter

Beta particles interact with matter primarily through ionization and excitation of atoms. As they pass through matter, they lose energy and eventually come to a stop.

Biological Effects

Beta particles can cause damage to living tissue, primarily through ionization. They can penetrate the outer layer of skin and pose a risk if ingested or inhaled. The biological effects depend on the energy of the beta particles and the duration of exposure.

Applications

Beta particles have several applications in medicine and industry:

• Medical Imaging and Treatment: Beta-emitting isotopes are used in radiotherapy to treat certain types of cancer. For example, strontium-90 is used in the treatment of bone cancer.

• Industrial Uses: Beta particles are used in thickness gauges to measure the thickness of materials such as paper and metal sheets.

Safety Precautions

When working with beta-emitting materials, it is important to use appropriate shielding and protective equipment to minimize exposure. Safety protocols include the use of gloves, lab coats, and safety glasses, as well as proper ventilation to prevent inhalation.

See Also

• Alpha particles
• Gamma rays
• Radioactive decay
• Radiation protection

References

• "Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards," International Atomic Energy Agency, 2014.
• "Introduction to Radiological Physics and Radiation Dosimetry," Frank H. Attix, 1986.