Electricity in Gases (High Voltage Physics Series)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1915 Excerpt: ...figure 40. The paths of the a particles are very distinct, since a large number of ions are generated by each ray, and a dense cloud is obtained along the path of each particle. The drops are so numerous that the cloud when illuminated appears to be a continuous bright line. The a rays are generally straight over the greater part of their length, but they are nearly all bent, often abruptly, in the last two millimetres of their course. The length of the path as shown by this method is in good agreement with that previously found by experiments on the conductivity at various distances from the source. Figure 41 illustrates the effect of the ionization produced by radium emanation. The bright lines originating at various points in the gas represent the tracks of the a particles emitted by molecules of the radio-active gas. The tracks produced by the /3 rays (figure 42) are not so distinct, as a small number of ions are produced per centimetre of the path of each /3 particle. At irregular intervals along the path, groups of twenty or thirty ions appear to have been generated within a small area. The occurrence of a group may be interpreted as indicating that in certain cases when an electron is separated from a molecule by a j8 ray, the electron may have sufficient energy to ionize other molecules in its neighbourhood. The path of a /3 particle is nearly straight when the velocity is high, but as the velocity diminishes the number of ions generated per t centimetre of its path increases, and at the same time the ray is more readily deviated by colliding with a molecule. At a later stage of slower velocity, the path of the particle becomes curled up and resembles the paths of the secondary i corpuscular rays generated by Rontgen rays. Figure 43 shows the effect...