The secondaryγ-radiation (“Bremsstrahlung”) excited by theβ-particles of 1532P

Abstract

Abstract Aγ-radiation emitted by radiophosphorus 15 32Phas been detected. The intensity of this radiation is of the same order as those of theγ-radiations from RaE and UX. The supposition is made that thisγ-radiation is the internal “Bremsstrahlung” excited by the disintegration electrons, when leaving the nucleus. Also the external “Bremsstrahlung” was found, excited by the electrons of 32 15P, impingeing on the nuclei of the material in which they are absorbed. The two radiations could be investigated separately by means of the application of a magnetic field. The intensity of the external radiation in the case of complete absorption of theβ-particles was compared for C, Al, Fe, Cu, Sn, Pb and was found to be roughly proportional to Z 2A −1 ( Z: atomic number; A: atomic weight), in accordance with the theory of Bethe and Heitler. Further absorption measurements were made for both radiations in Al and Pb. For these two elements the external radiation contains relatively more quanta of low energy than the internal radiation. We have been able to estimate from the experimental data the total energy contained in the two radiations. For the internal radiation this estimate leads to about 0.012 mc 2 = 6.000 eV per disintegration electron and for the external radiation excited in aluminium to about 0.002 mc 2 = 1.000 eV per electron. Using the measurements of Lyman on the magneticβ-spectrum of 15 32P, we have calculated from the theory of Knipp and Uhlenbeck the energy of the internal radiation, and from the theory of Bethe and Heitler the energy of the external radiation. The first turned out to be equal to 0.0022 mc 2 = 1100 eV per desintegration electron, which is about 5.5 times smaller than the experimental value. For the second the calculation yielded 0.0087 mc 2 = 4300 eV, which is about 4 times larger than the value estimated from the experiments. Further, it was found that the absorbability of the internal radiation is somewhat less than that which was calculated from the energy distribution given by the theory of Knipp and Uhlenbeck.