Title: Positive Electrons: Focussing of Beams, Measurement of Charge-to-Mass Ratio, Study of Absorption and Conversion into Light
Abstract: 1. Description of a method ("method of the trochoid") of concentrating and focussing weak electron beams so that they form strong sharp lines on a photographic plate. 2. Displacement of the beam thus formed by an additional field, enabling the observer to recognize the sign of the charge and to estimate the charge-to-mass ratio of the particles, with an accuracy thus far brought up to 15 percent. 3. Absorption, in thin films of platinum and a large number of other elements, of the positive and negative electrons proceeding from a source composed of a radioactive substance emitting strong gamma-rays and enclosed in lead; it is shown that the absorption follows an exponential law over a wide range of thicknesses, and the value of the mass absorption-coefficient is obtained from observations on the imprint made upon a photographic plate behind the absorber. 4. When in the foregoing experiments the thickness of the absorber is increased beyond about 500 mg/${\mathrm{cm}}^{2}$, it becomes evident that the imprint on the plate is partly due to something else than the transmitted electrons. This "something else" is considered to be radiation; with negative electrons it consists entirely of secondary x-rays, with positive electrons there is an additional component ascribed to the merging of positive with negative electrons and their conversion into photons. 5. The absorption-coefficient of these photons implies that their energy is about 0.5 MEV, and the intensity of the radiation implies that there are about two of them per positive electron---two results which agree well with Dirac's theory. 6. Positive electrons have also been observed in conditions where it seems that they proceed directly from radioactive substances.
Publication Year: 1934
Publication Date: 1934-06-01
Language: en
Type: article
Indexed In: ['crossref']
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Cited By Count: 18
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