Abstract
ATOMIC projectiles and their applications formed the subject of the nineteenth Thomas Hawksley lecture delivered by Lord Rutherford on November 4 before the Institution of Mechanical Engineers. At present the maximum velocity that can be communicated to matter in bulk is not more than two miles a second. This is of the same order of magnitude as the average speed of the molecules of gases under ordinary conditions. But if we turn to individual charged atoms, methods have been developed which enable us to produce atomic projectiles moving with enormous speed. When the velocity becomes comparable with that of light, we have to take into account the change of mass of the particle with speed. As the velocity is generally produced by the acceleration of the particle in an electric field, it is convenient to speak of a thousand-volt particle, meaning thereby that the particle has the speed and energy equal to that gained in passing freely between two points differing in potential by a thousand volts. In the experiments of Cockcroft and Walton in the Cavendish Laboratory, Cambridge, a steady difference of potential up to 600,000 volts can be maintained in the accelerating tube, thus producing a stream of swift protons corresponding to a current of 20 micro-amperes. By the multiple acceleration of charged atoms, Lawrence and Livingston in California have been able to obtain a stream of protons of energy so high as 1,200,000 volts by the use of a voltage so low as 4,000 volts.
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Atomic Projectiles. Nature 130, 730–731 (1932). https://doi.org/10.1038/130730d0
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DOI: https://doi.org/10.1038/130730d0