The ejection of protons from nitrogen nuclei, photographed by the Wilson method

Extract

The original experiments of Rutherford and later those of Rutherford and wick have shown that fast alpha-particles are able by close collisions to protons from the nuclei of many light elements. In particular the protons boron, nitrogen, fluorine, sodium, aluminium and phosphorus have great es, and are emitted in all directions relative to the velocity of the bombard-alpha-particles. The scintillation method used in these experiments can give direct information about the motion after the collision of the residual nucleus of the alpha-particle itself. The proton alone has sufficient range to make direction by the scintillation method possible. The Wilson Condensation provides the obvious and perhaps the only certain way of observing emotion of these two particles. Of the “active” elements mentioned, gen can at once be selected as the most suitable for a first investigation. According to Rutherford and Chadwick the maximum forward and backward ranges of the protons ejected by 7 cm. alpha-particles from nitrogen are 4 and 18 cms. The total number emitted in all directions by a million 8·6 cm alpha-particles can be estimated, from their data, to be about 20. This number decreases rapidly with the range of the alpha-particles.