Scattering of α-Particles by Light Atoms

Abstract

IN a recent discussion at the Royal Society (NATURE, vol. 123, p. 246), Sir Ernest Rutherford pointed out the great importance of the experiments on the scattering of α-particles by light atoms like those of magnesium, aluminium, helium, and hydrogen which are being carried out at the Cavendish Laboratory by himself and his co-workers Bieler, Chadwick, and others. The results of these experiments show very wide variation from the classical expression obtained on the assumption of an inverse square law, and led Rutherford and Bieler to the view that the repulsive force between positively charged particles changes into an attractive one when the distance of approach is less than 3 × 10⁻¹³ cm. Many attempts have been made to get an exact expression for this force. Bieler thought the force to be given by the law F = Ze²/r − μ/r⁴, while Debye and Hardemeier took the additive term to be inversely proportional to the fifth power of the distance.