Glossary

A-Bomb
An abbreviation for atomic bomb.
See; Fission, Nuclear Weapon.
Absorbed Dose
The amount of energy imparted by nuclear radiation to unit mass of absorbing material. The unit is the rad.
See; Dose, Rad.
Acute Exposure
Acute exposure is exposure to a large, single dose of radiation, or a series of doses, for a short period of time.
African Nuclear-Weapon-Free-Zone
See; Treaty of Pelindaba
Afterwinds
Wind currents set up in the vicinity of a nuclear explosion directed toward the burst center, resulting from the updraft accompanying the rise of the fireball.
See; Fireball.
Agreed Framework
The 1994 agreement between the United States and North Korea (Democratic People's Republic of Korea, DPRK) to "freeze" the DPRK nuclear program. In addition, the DPRK agreed to remain a party to the nuclear Non-Proliferation Treaty (NPT) and accept International Atomic Energy Agency (IAEA) full-scope safeguards.
Air Burst
The explosion of a nuclear weapon at such a height that the expanding fireball does not touch the earth's surface when the luminosity is a maximum.
See; Fireball.
Air Launched Cruise Missile (ALCM)
See; Cruise Missile.
Alpha Decay
A helium 4 nucleus (alpha particle) that emerges spontaneously from some heavy nucleus, e.g., plutonium.
See; Alpha Particle.
Alpha Particle
A particle emitted spontaneously from the nuclei of some radioactive elements. It is identical with a helium nucleus, having a mass of four units and an electric charge of two positive units. The alpha particle has a very short range in air and a very low ability to penetrate other materials, but it has a strong ability to ionize materials. Alpha particles are unable to penetrate even the thin layer of dead cells of human skin and consequently are not an external radiation hazard. Alpha-emitting nuclides inside the body as a result of inhalation or ingestion are a considerable internal radiation hazard.
See; Alpha Decay, Fission Products, Radioactivity.
Americium
An artificial radioactive element with atomic number 95 (symbol Am), produced in nuclear explosions and reactors; emits alpha particles.
See; Alpha Decay, Fission Products, Radioactivity.
Angstrom
A unit of length, represented by Å , equal to 10-8 centimeter. It is commonly used to express the wavelengths of electromagnetic radiations in the visible, ultraviolet, and X-ray regions.
Antarctic Treaty
The Antarctic Treaty internationalizes and demilitarizes the Antarctic continent. It specifies that Antarctica be used for peaceful purposes only; all activities of a military nature, including testing of any type of weapon, are prohibited.
Anti-Ballistic Missile (ABM) Treaty
The ABM Treaty, was signed by the United States and the former Soviet Union, constrained strategic missile defenses to a total of 200 launchers and interceptors per country. The treaty was modified in 1974, reducing the number of ABM deployment areas permitted for each side from two to one and the number of ABM launchers and interceptors from 200 to 100. However, on June 13, 2002, the United States officially withdrew from the ABM Treaty in order to pursue the development of a missile defense system.
Anti-Satellite Weapon (ASAT)
A system designed to destroy or disable an enemy satellite in orbit.
See; SDI.
Arms Control
Arms control, a term popularized in the early 1960s, refers to the voluntary limitation or reduction of weapons and their means of delivery, between and among countries, through negotiation. It is distinct from disarmament, which seeks to eliminate, also by international agreement, the means by which countries wage war. While arms control compiled a mixed record during the post-World War II era, revolutionary changes in international politics during the early 1990s-most especially the collapse of the USSR and the end of the Cold War-have opened up promising new opportunities for radical reductions in the nuclear and conventional weapons arsenals of the major powers.
Atom
The smallest particle of an element that still retains the characteristics of that element. Every atom consists of a positively charged central nucleus, which carries nearly all the mass of the atom, surround by a number of negatively charged electrons.
See; Nucleus.
Atomic Bomb
A term sometimes applied to a nuclear weapon utilizing fission energy only. The atomic bomb is an explosive device that depends upon the release of energy in a nuclear reaction known as fission, which is the splitting of atomic nuclei. With a release of energy on the order of a million times greater than an equal weight of chemical high-explosive
See; Fission, Nuclear Weapon.
Atomic energy
Energy released in nuclear reactions. Of particular interest is the energy released when a neutron initiates the breaking up or fissioning of an atom's nucleus into smaller pieces (fission), or when two nuclei are joined together under millions of degrees of heat (fusion). It is more correctly called nuclear energy.
See; Fission, Fusion.
Atomic Fission
See; Fission.
Atomic Mass Unit
A relative mass unit based on the atomic weight of carbon 12, which is taken to be 12; the atomic mass of hydrogen is 1.008 amu. The atomic mass unit (amu) is 1.660 -27 kg.
Atomic Nucleus
The nucleus is the small, massive center of the atom, containing neutrons and protons bound together by the nuclear force, the strongest force known in nature. The diameter of the nucleus is about (10 to the power of - 12) cm, which is about one ten-thousandth of the diameter of the atom itself.
Atomic Number
The atomic number of an element, which indicates its place in the periodic table of elements, is the number of protons (positively charged particles) in the nucleus of one of its atoms. If an atom is electrically neutral, the same number of electrons are present. Atomic number is often symbolized with the letter Z and is shown as a numerical subscript to the left of its chemical symbol. For example, the letter C preceded by a superscript number 12 and a subscript number 6 indicates a carbon atom of atomic mass 12 and atomic number 6, the difference being equal to the number of neutrons present in the nucleus.
See; Nucleus.
Atomic Weight
The relative mass of an atom of the given element. As a basis of reference, the atomic weight of the common isotope of carbon (carbon-12) is taken to be exactly 12; the atomic weight of hydrogen (the lightest element) is then 1.008. Hence, the atomic weight of any element is approximately the mass of an atom of that element relative to the mass of a hydrogen atom.
Airborne Warning and Control System (AWACS)
A flying command post. AWACS has the capacity to detect hostile radar systems and aircraft and control friendly air forces.
Atoms for Peace
The U.S. program announced by President Dwight D. Eisenhower at the United Nations in December 8, 1953, to share nuclear materials and technology for peaceful purposes with other countries. This program required countries receiving nuclear materials to agree to inspections of the transferred technology to ensure it was not used for military purposes.

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