Beta Radiation
Beta radiation is a type of ionizing radiation that is emitted during the process of beta decay, which occurs when an unstable atomic nucleus transforms to achieve greater stability. This decay can produce two types of beta particles: electrons in negative beta decay and positrons in positive beta decay. Beta particles are high-speed subatomic particles that can penetrate materials and are utilized in various medical applications, particularly in the diagnosis and treatment of conditions such as cancer.
The process of beta decay is governed by the weak nuclear force, one of the four fundamental forces in nature, which facilitates the transformation of neutrons to protons or vice versa within the nucleus. While beta radiation has beneficial applications, it can also pose risks to living organisms by altering the chemical structure of DNA, potentially leading to harmful mutations.
Additionally, beta particles have practical uses beyond medicine, such as testing the thickness of materials in manufacturing. However, the management of radioactive waste, which includes beta radiation, raises significant environmental and health concerns. Overall, understanding beta radiation is essential for both its applications and its implications for safety and health.
Beta Radiation
FIELDS OF STUDY: Electromagnetism; Atomic Physics; Nuclear Physics
ABSTRACT: Beta radiation is generated by the release of beta particles, which are electrons or positrons. Beta radiation is emitted by radioactive atomic nuclei undergoing beta decay because they have too many neutrons or protons. Ernest Rutherford first described beta radiation in 1899.
PRINCIPAL TERMS
- antineutrino: a subatomic particle with a neutral charge, the antiparticle to the neutrino, which is emitted during beta decay.
- electron: a negatively charged subatomic particle that is often bound to the positive charge of the nucleus but can also exist in a free state in an atom.
- half-life: the average time it takes for half of the unstable nuclei in a radioactive element to undergo radioactive decay.
- mutation: in biology, a change in the structure of a gene. Ionizing radiation such as beta radiation can alter the electric charge of the atoms in a gene.
- positron: a subatomic particle that has the same mass as an electron as well as an equal-but-opposite electric charge, that is, a positive charge.
- radiation: energy transmitted via electromagnetic waves (e.g., light, heat, x-rays) or subatomic particles (e.g., alpha particles, beta particles).
- radioisotope: a chemical element with unstable nuclei that give off radiation due to variations in the number of neutrons they contain.
- weak interaction: interaction between subatomic particles at a short distance that is influenced by the weak nuclear force, one of the four fundamental forces in nature.
- revolution: describes circular motion wherein an object circles an internal axis (e.g. the moon spinning about its axis); contrast to rotation, wherein the axis is external (e.g. the moon orbiting the earth).
Radiation without Waves
In many cases radiation refers to electromagnetic radiation (EMR), which includes visible light, x-rays, and ultraviolet rays. Rather than through waves like EMR, beta radiation is transmitted by subatomic particles ejected at high speed when a radioactive atom’s nucleus undergoes beta decay. British physicist Ernest Rutherford (1871–1937) described beta radiation in 1899.
Beta decay and the particles it produces can be sorted into two types according to electric charge. Negative beta decay (beta-minus decay) occurs in an unstable atomic nucleus with too many neutrons. One of its excess neutrons is turned into a proton, an electron, and an antineutrino. The electron, a beta particle, is released from the nucleus along with the antineutrino. Positive beta decay (beta-plus decay) occurs in an unstable atomic nucleus with too many protons. One of its excess protons is turned into a neutron, a positron, and a neutrino. The positron, also a beta particle, and the neutrino are released from the nucleus.
In the medical field, beta radiation and beta particles are used in diagnosis, imaging, and sometimes treatment for certain conditions, especially cancer. Some beta particles can pass through skin and tissue. Beta radiation is ionizing, meaning that beta particles can alter the electrical charge of the atoms they hit. Thus, when beta particles hit cells and other living tissue, they can cause damage by altering the chemistry. When beta particles hit DNA, they can change the structure of genes and induce potentially harmful mutations.
Radioactivity and Isotopes
An atom is said to be radioactive if it gives off ionizing radiation. This radiation is the result of an unstable nucleus emitting energy in the form of subatomic particles in order to reach a more stable state. The three main forms of radiation emitted during radioactive decay are alpha, beta, and gamma. The average time it takes for half of a given sample of radioactive material to undergo decay is known as its half-life.
The number of protons in an atom’s nucleus determines what element it is. Known as the atomic number, it is used to sort elements in the periodic table. The nucleus of an atom of a given element will always have the same number of protons as every other atom of that element as well as the same general chemical properties. However, the number of neutrons may vary. This variation in the number of neutrons creates isotopes. Isotopes have more or less total atomic weight because of the addition or subtraction of neutrons; for example, carbon-14 is an isotope of carbon, which has an atomic number of 12. Isotopes can occur naturally or can be made by humans. Some isotopes are stable. Radioisotopes are unstable and subject to spontaneous radioactive decay. All elements above atomic number 83 are unstable and radioactive. Most below this number have at least one radioisotope.
The Weak Interaction and Beta Decay
Beta decay is mediated by the weak interaction, which is also known as the weak nuclear force. It was through the study of beta decay that Enrico Fermi first described the weak nuclear force in 1934 to explain this previously mysterious process of decay. The weak nuclear force is one of the four fundamental forces of physics. The other three are the strong nuclear force, the gravitational force, and the electromagnetic force. The strong nuclear force is much more powerful than the weak nuclear force, but its range is more limited. When the nucleus gets too big (that is, contains too many protons or neutrons), the weak force causes it to split up into smaller pieces and release beta particles.
Beta Particles in Everyday Life
The penetrating power and ionizing ability of beta particles make them useful tools for targeted radiation therapy for some cancers. They can kill target cells with minimal damage to surrounding tissue. On the other hand, this also makes them dangerous when exposure is not controlled. Beta particles also have a modest penetrating power that makes them useful for testing the thickness of manufactured materials, such as metal foil or paper, by measuring how much of the radiation is stopped by the material as it passes through. It is perhaps most relevant to everyday life as a by-product of nuclear waste produced by reactors. The question of how best to dispose of this waste is of major environmental, health, and political concern.
Bibliography
"Beta Particles." Radiation Protection. US Environmental Protection Agency, 7 Feb. 2013. Web. 26 May 2015.
Davidson, Michael W. "The Rutherford Experiment." Molecular Expressions: Electricity & Magnetism. Florida State U, 28 Feb. 2014. Web. 26 May 2015.
"Electromagnetic Radiation." Encyclopaedia Britannica. Encyclopaedia Britannica, 26 Nov. 2014. Web. 26 May 2015.
"Glossary: Beta Decay." Jefferson Lab. Thomas Jefferson Natl. Accelerator Facility, n.d. Web. 26 May 2015.
Lucas, Jim. "What Is the Weak Force?" LiveScience. Purch, 24 Dec. 2014. Web. 26 May 2015.
"Radiation Basics." US Nuclear Regulatory Commission. USNRC, n.d. Web. 26 May 2015.