English: Diagram of a cyclotron, a particle accelerator invented by Earnest O. Lawrence in 1932 and widely used from the 1930s to the 1950s. It consists of a pair of "D" shaped sheet metal electrodes called "Dees" placed face to face inside a vacuum chamber, between the poles of an electromagnet. An oscillating radio frequency voltage of several thousand volts is applied to the dees. Atomic particles to be accelerated, such as protons are released in the center. The magnetic field causes them to travel in a spiral path from the center to the rim of the dees, being accelerated each time they pass from one electrode to the other. When the particles reach the rim they pass out of the dees through a small gap and strike a target. In this diagram the electromagnet pole pieces are not shown full size; they must be at least as big as the dees to create a uniform field.
Caption: How the cyclotron works. Size of the magnets has been kept down to show the path of the electron
This 1947 issue of Radio-Craft magazine would have the copyright renewed in 1975. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1974, 1975, and 1976 show no renewal entries for "Radio-Craft". Therefore the magazine's copyright was not renewed and it is in the public domain.
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Este archivo se encuentra en el dominio público en los Estados Unidos porque fue publicado en ese país entre los años 1929 y 1963, y, teniendo un aviso de derechos de autor, no se renovó su protección. A menos que su autor haya fallecido años antes, se mantiene bajo propiedad intelectual en los países o zonas que no aplican la regla del plazo más corto para las obras estadounidenses, como Canadá (70 años p.m.a.), China continental (50 años, a excepción de Hong Kong o Macao), Alemania (70), Suiza (70), México (100) y otros países con reglas particulares. Vea Commons:Hirtle chart como referencia e información.