IN a recent note, Champion and Barber1 have suggested that the γ-rays of radium E may arise from the production of electron-pairs by internal absorption of β-rays, the γ-rays being thus recombination radiation. It seems possible that the γ-rays of polonium2 may be due similarly to the production of electron-pairs by internal absorption of α-rays. My analysis3 of the absorption curve of this radiation suggested quantum energies of (1·0 ± 0·1) and (0·4 ± 0·1) million electron volts, equal numbers of the two types (about 12 per million -particles) being emitted. This is consistent with identification as recombination radiation, and the process is consistent with conservation of momentum and energy.
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