The Artificial Radioactivity of Copper, a Branch Reaction

The artificial radioactivity of longer half-life produced in copper by deuteron bombardment is studied. It is found to emit both electrons and positrons in the ratio 1.6 to 1. The half-life is found to be 12.8±0.1 hours. The excitation curve of positrons and electrons for deuterons of different energies is studied and found to agree with the theoretical expression of Oppenheimer and Phillips. The upper limits of the energy distribution of the positrons and electrons are obtained from cloud chamber photographs, and are found to be 0.79 and 0.83 Mev, respectively. The results are interpreted as showing that this activity is due to ${\mathrm{Cu}}^{64}$ which branches in disintegrating, going either to zinc or nickel.