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The β- and γ-radiation of RaC″

Published online by Cambridge University Press:  24 October 2008

S. Devons  and
G. J. Neary
S. Devons
Affiliation:
Trinity College
G. J. Neary
Affiliation:
Gonville and Caius College
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Extract

Absorption experiments have been carried out on the β- and γ-rays of RaC”. The range of the β-rays in aluminium corresponds to an energy limit of (1·95 ± 0·15) × 106 e.v.; the absorption coefficient of the γ-rays in copper corresponds to a fairly homogeneous radiation of quantum energy equal to (5 ± 1) × 106 e.v. The energy of disintegration is, within the limits of error, in agreement with the value 6·1 × 106 e.v. to be expected from the known energies of the other disintegrations in the RaC branches.

Type
Research Article
Information
Mathematical Proceedings of the Cambridge Philosophical Society , Volume 33 , Issue 1 , March 1937 , pp. 154 - 163
Copyright
Copyright © Cambridge Philosophical Society 1937

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References

* Fajans, , Phys. Zeits. 12 (1911), 369.Google Scholar

† Rutherford, and others, , Proc. Roy. Soc. 129 (1930), 211.CrossRefGoogle Scholar

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* Since the branching ratio of RaC” is 2·10−4, the amount of RaA present must be much less than 2·10−4 of the initial equilibrium amount; in one hour, the RaA decays to 10−6 of the initial amount, while the RaC decays to one-half.

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† A further difficulty in the case of the γ-ray measurements was that, with the thicker absorbers, the source had to be moved farther from the counter. This slight alteration of the geometrical conditions was, however, shown to be considerably less serious than might have been supposed: by performing a check experiment with the γ-rays of Th(B + C) in which first the procedure was identical with that for RaC″ and secondly the source was kept fixed at the lowest position needed for the thickest absorber, very similar absorption coefficients were found.

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* The tendency to underestimate the energy of the upper limit deduced from absorption measurements is also obviated, since here the error will be about the same and in the same direction for both ThC and RaC”.

† Henderson, , Proc. Roy. Soc. 147 (1934), 572.CrossRefGoogle Scholar

‡ Sargent, , Proc. Roy. Soc. 139 (1932), 659.CrossRefGoogle Scholar

§ Lecoin, and Goldstein, , C. R. Acad. Sci. 13 (1936), 1169.Google Scholar

* Diagrams of the variation of the different components of the absorption coefficients in several elements with energy may be found in Heitler, , Quantum theory of radiation (Oxford, 1936), p. 216.Google Scholar

† hν=5·2 mc2 for ThC” γ-rays.

* Rutherford, and others, , Proc. Roy. Soc. 139 (1933), 617.CrossRefGoogle Scholar

* Chadwick, and Goldhaber, , Proc. Roy. Soc. 151 (1935), 479.CrossRefGoogle Scholar