Some of the History Surrounding the Oliphant et al. Discovery of dd Fusion and an Inference of the d(d,p)t Cross Section from This 1934 Paper

A review of the flurry of papers involving deuteron beams in 1933 and 1934 reveals some aspects of historical significance. A team led by Lawrence saw several mega-electron-volt protons and neutrons from deuteron-plus-deuteron (dd) fusion in 1933 before the discovery of this process by Oliphant et al. in 1934. However, Lawrence et al. failed to notice deuteron contamination in their targets, and instead incorrectly concluded that the protons and neutrons were being emitted back to back from the breakup of the deuterons in the relevant center-of-mass frame. By observing disintegrations induced by deuteron beams incident on deuterated targets, Oliphant et al. correctly identified dd fusion proceeding through an intermediate excited ⁴He nucleus that broke up into either back-to-back protons and tritons or back-to-back neutrons and ³He nuclei.

Here we use Oliphant et al.’s proton production rates to infer d(d,p) cross sections that are twice the known modern values. This discrepancy is likely due to our lack of knowledge of some key aspects of Oliphant et al.’s 1934 experimental setup. However, the deuterium beam energy dependence of Oliphant et al.’s d(d,p) proton production rate is clearly consistent with the quantum mechanical tunneling through the Coulomb barrier associated with the fusion of two hydrogen isotopes.