Letter | Published:

Internal Pair Conversion

Nature volume 162, page 264 (14 August 1948) | Download Citation



WHEN a γ-quantum, emitted from the nucleus of a radioactive atom, is absorbed by the same atomic system, an ordinary electron and a positron may be liberated if the energy of the γ-quantum is greater than 2mc2. This effect has been calculated by Jaeger and Hulme1 on the assumption that the γ-ray is electric dipole or quadrupole radiation. I have performed the corresponding calculation for the magnetic dipole radiation and the element Z = 84. In calculating the coefficient, Dirac‘s exact wave equation of the electron is used and the process is interpreted as the transition of an ordinary electron from a negative energy to a positive energy state. The results are given in the accompanying table, where the energies are expressed in units of mc2 and N is the number of positrons (which is, of course, equal to the number of the pairs created) per unit energy range.

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  1. 1.

    Proc Roy. Soc., A, 148, 708 (1935).

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  1. Gonville and Caius College, Cambridge. June 22.

    • M. H. WANG


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