File:Lawrence 27 inch cyclotron dees 1935.jpg
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Summary
| Description |
English: The vacuum chamber of a cyclotron particle accelerator from 1935 with its cover off, showing the two accelerating electrodes or "dees". This was the 27 inch cyclotron built by Ernest O. Lawrence at Univ. of California Berkeley Radiation Laboratory in 1932 that could accelerate deuterons to 4 Mev. In operation, this vacuum chamber was sandwiched between the 27 in. diameter pole pieces of a huge 75 ton electromagnet which produced a vertical magnetic field of 16,000 gauss with a current of 65 A in its windings. The two hollow sheet copper "D" shaped electrodes, or "dees" 22 in. diameter by 2 in. high, form a cylindrical space within which the particles, hydrogen or duterium ions, travel. The vertical magnetic field bends the particle's path into a circle. An oscillating radio frequency potential of 13,000 volts from an electronic oscillator at about 12 MHz is applied between the two dees through the two feedlines at right rear. Each time the particles cross the gap the electric field accelerates them. The particles travel in a spiral path clockwise from the center of the dees to the rim, where they pass out of the dees through a gap and strike a target located at bottom right. |
| Date | |
| Source | Retrieved October 24, 2014 from John B. Livingood, "Radioactivity by Bombardment" in Electronics magazine, McGraw-Hill Publishing Co., New York, Vol. 8, No. 11, November 1935, p. 6 on http://www.americanradiohistory.com |
| Author | John B. Livingood |
| Permission (Reusing this file) |
This 1935 issue of Electronics magazine would have the copyright renewed in 1963. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. Search of the Renewals for Periodicals for 1962, 1963, and 1964 show no renewal entries for Electronics. Therefore the magazine's copyright was not renewed and it is in the public domain. |
Licensing
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This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 22:16, 31 December 2014 | | 1,112 × 830 (140 KB) | wikimediacommons>Chetvorno | User created page with UploadWizard |
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