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.
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.
A type of atmospheric test in which the explosion of a nuclear weapon occurred at such a height that the expanding fireball did not touch the earth’s surface before the fireball reached its maximum luminosity. See; Fireball.
A type of atmospheric test in which a nuclear device was dropped from an aircraft and exploded in the atmosphere.
A helium 4 nucleus (alpha particle) that emerges spontaneously from some heavy nucleus, e.g., plutonium. This lowers the atomic number of the nucleus by two and its mass by four. See; 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.
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.
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, 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.
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.
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.
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.
The sum of the number of protons and neutrons in the nucleus of an atom.
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.
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.
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.
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.
A test conducted above ground or above water (i.e., in the open air).
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.
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.