Published online by Cambridge University Press: 24 October 2008
Experiments carried out with the aim of elucidating the action of the α-particle counter are described. A normal counting circuit including an ionization chamber with point and plane electrodes was used. The “wave-form” and intensity of the transient impulses resulting from discharges stimulated by single electrified particles have been determined using a cathode-ray oscillograph. It is found that the nature of the impulse is determined largely by the capacity and resistance of the system, and not by the nature of the electrical stimulus. The potential impulse normally detected by string electrometer methods is shown to be proportional to the current responsible for the recharging of the electrostatic capacity of the counter after the rapid discharge of the capacity initiated by the electrified particle.
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* Cf. Townsend, Electricity in Gases, chap. xi, § 298.
† C.R. 150, 1286 (1910)Google Scholar.
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* Probably this was the case in the original experiments of Rutherford and Geiger (loc. cit.), of Hess and Lawson (Wien. Ber. 127, 3 and 4 (1918)), and of Greinacher (Zeit. f. Phys. 23, 6, 361 (1924)Google Scholar).
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∥ At the lowest pressures worked with it was however noticed that the fraction of a time-period during which the counter conducted was greater than at higher pressures.
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* Contrast this with Kutzner's statement (Zeit. f. Phys. 23, 128 (1924)) that additional capacity and resistance are not essential to the action of the point and plane counter.