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XVII.—The Ionizing Efficiency of Electronic Impacts in Air

Published online by Cambridge University Press:  15 September 2014

John Thomson
Affiliation:
University of Glasgow
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Summary

Experiments are described, the aim of which is the determination of the energy spent in producing one pair of ions when electrons of velocity corresponding to 50–270 volts are totally absorbed in air. It is found that this energy varies with the initial speed of the electron, but that it asymptotes to the value 37 ± 2 electron-volts when the energy of the electron is very great.

This value of the “volts per ion pair” is compared with those found by other experimenters. A correlation of the three electronic “constants,” the range of the electron, the ionization per unit path, and the total ionization is attempted. It is concluded that, unless in the case of very fast cathode rays or β-particles, the “ionization per unit path,” as measured by ionization chamber experiments, has no meaning.

Type
Proceedings
Copyright
Copyright © Royal Society of Edinburgh 1932

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References

page 127 note † Johnson, , Phys. Rev., 10, p. 609 (1917)CrossRefGoogle Scholar; Anslow, , Phys. Rev., p. 484 (1925)CrossRefGoogle Scholar; Lehmann, and Osgood, , Proc. Roy. Soc., A, 115, p. 609 (1927CrossRefGoogle Scholar); Eisl, , Ann. d. Physik, 3, 3, p. 277 (1929).CrossRefGoogle Scholar

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page 140 note * Wilson, C. T. R., Proc. Roy. Soc., 104, p. 192 (1923).CrossRefGoogle Scholar