Collision of Two Light Quanta

TLDR

Dirac treated electron–positron recombination and its link to the Compton effect before the positron was experimentally discovered. The paper presents calculations for positron–electron pair production from two‑photon collisions. The authors compute pair production in two‑photon collisions and apply the results to high‑energy cosmic photons interacting with interstellar background radiation. The angular distribution of produced pairs depends on polarization, and the absorption effect of such photons is negligible.

Abstract

The recombination of free electrons and free positrons and its connection with the Compton effect have been treated by Dirac before the experimental discovery of the positron. In the present note are given analogous calculations for the production of positron electron pairs as a result of the collision of two light quanta. The angular distribution of the ejected pairs is calculated for different polarizations, and formulas are given for the angular distribution of photons due to recombination. The results are applied to the collision of high energy photons of cosmic radiation with the temperature radiation of interstellar space. The effect on the absorption of such quanta is found to be negligibly small.