Disintegration of Separated Isotopes of Magnesium by Deuterons

IN a recent study of the transmutation of a number of elements by deuterons1, the emission of three groups of protons from magnesium under deuteron bombardment was reported. These groups were assigned to particular isotopes by arguments based chiefly on the value of the energy released in similar reactions with other elements and on differences between the excitation functions of the groups. We have now been able to bombard separated isotopes, and the accompanying graph shows the proton groups observed from targets of magnesium-24, -25 and -26 deposited on stainless steel. The deuteron energy was 930 keV. as in the earlier experiments, and the protons were observed at right-angles to the incident beam. The three targets for which the results are shown in the figure were cut from larger areas on which the magnesium was deposited; but since the deposits were not uniform, the target thicknesses could not be accurately estimated. In the case of the magnesium-24 target, observation of the width of a (ργ) resonance-level suggested an equivalent thickness of about 10 keV. ; the thickness of the magnesium-25 and -26 targets was unknown, and the relative intensities of the groups shown in the graph are therefore unlikely to be those which would be obtained from targets in the normal isotopic ratio of thickness.