Radiative Collisions of Neutrons and Protons

Abstract

IT has recently been shown by Lea¹ that the passage of neutrons through paraffin wax and through liquid hydrogen gives rise to a gamma radiation of 1–6 × 10⁶ e. volts energy, as well as recoil protons. As pointed out by Lea and Chadwick, the energy of these rays corresponds roughly to that which would be emitted in the radiative combination of a neutron and a proton to form a diplon. We have therefore calculated the probability of such a radiative collision on the assumption that the neutron behaves as a fundamental charge-free particle throughout the collision, so that the radiation arises only from the acceleration of the proton by the field of force of the neutrpn. A dipole moment may then be associated with the system and the calculation carried out in the usual manner². The result is that, for the range of energies involved in the experiments, combination should not take place more frequently than once in every 1000 collisions (the effective radius for diplon formation is about 2 × 10¹⁴ cm.). This is much smaller than the observed frequency of about 1 in 4 collisions. We have also calculated the probability of a proton radiating in the impact without binding taking place, and find it to be even smaller. These results do not depend appreciably on the form of interaction assumed between neutron and proton.