Deuteron-Induced Radioactivities

Abstract

Bombardment of several elements with 5-MEV deuterons produces the following radioactivities. Commercial copper decays with a half-life of 130±10 days, emitting gamma-rays and very slow electrons. Attempts at chemical identification of probable radioactive products have been inconclusive, and the activity may be due to some unknown impurity in the copper. Zinc emits electrons with half-lives of 97±10 hours, 25±2 hours, 12±1 hours and 1±0.3 hours; the third of these is possibly due to radio ${\mathrm{Cu}}^{64}$ which has the same period. Antimony exhibits electron activities with half-lives of 50±4 days, 68±2 hours (confirming the 2.5 day period found by Fermi with neutrons) and 24±2 hours. Ruthenium shows half-lives of 46±3 days, 11±2 days, 39±1 hours and 4±1 hours, all due to electrons. Bismuth yields electrons of 5 days half-life and alpha-particles which increase in number for three weeks and then remain practically constant. This is interpreted as the synthesis of radium E through the reaction ${}_{83}{}^{}{}_{}{}^{}\mathrm{Bi}_{}^{209}{}_{}{}^{}$+${}_1{}^{}{}_{}{}^{}\mathrm{H}_{}^2{}_{}{}^{}$→${}_{83}{}^{}{}_{}{}^{}\mathrm{Bi}_{}^{210}{}_{}{}^{}$ (i.e., Ra E)+${}_1{}^{}{}_{}{}^{}\mathrm{H}_{}^1{}_{}{}^{}$, followed by its natural decay to polonium and thence to lead. The range of the alpha-particles agrees with that of the alphas from natural polonium to within 0.5 mm, and the time required to reach maximum alpha-activity is consistent with the 140 day half-life of polonium.