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chain reaction

(Encyclopedia)CE5 Chain reaction: A neutron (n) strikes the uranium nucleus (U-235), causing it to split into fission products A and B and release two neutrons. These neutrons can in turn cause further fissions....

nuclear weapons

(Encyclopedia)nuclear weapons, weapons of mass destruction powered by atomic, rather than chemical, processes. Nuclear weapons produce large explosions and hazardous radioactive byproducts by means of either nuclea...

electron-volt

(Encyclopedia)electron-volt, abbr. eV, unit of energy used in atomic and nuclear physics; 1 electron-volt is the energy transferred in moving a unit charge, positive or negative and equal to that charge on the elec...

alkali metals

(Encyclopedia)alkali metals, metals found in Group 1 of the periodic table. Compared to other metals they are soft and have low melting points and densities. Alkali metals are powerful reducing agents and form univ...

alkaline-earth metals

(Encyclopedia)alkaline-earth metals, metals constituting Group 2 of the periodic table. Generally, they are softer than most other metals, react readily with water (especially when heated), and are powerful reducin...

Cohen, Samuel Theodore

(Encyclopedia)Cohen, Samuel Theodore, 1921–2010, American physicist known as the “father of the neutron bomb,” b. Brooklyn, N.Y., grad. Univ. of California, Los Angeles, 1943. He worked on the Manhattan Proje...

butoh

(Encyclopedia)butoh [Jap.,=dance of darkness], avant-garde dance form developed in post–World War II Japan. First performed in 1959 by the dancers Tatsumi Hijikata (1928–86) and Kazuo Ohno (1906–2010), butoh ...

spectroscope

(Encyclopedia)spectroscope, optical instrument for producing spectral lines and measuring their wavelengths and intensities, used in spectral analysis (see spectrum). When a material is heated to incandescence it e...

Roskilde

(Encyclopedia)Roskilde rôsˈkĭlə [key], city (1992 pop. 40,928), capital of Roskilde co., E Denmark, a port on the Roskilde Fjord (an arm of the Isefjord). Manufactures of this industrial city include processed ...

Sellars, Peter

(Encyclopedia)Sellars, Peter, 1957–, American director, b. Pittsburgh, grad. Harvard (1981). A highly innovative director, he began his career with the Boston Shakespeare Co. (1983–84) and Washington's American...