The Loss of Neutrons by Neutron Bombardment and the Radioactive Isotopes of Scandium

Abstract

The bombardment of lithium by deuterons of 6.3 Mev energy yields neutrons of energy up to 20 Mev. These neutrons are in turn able to produce disintegrations by the ejection of two neutrons from bombarded nuclei. In the case of scandium there has been evidence that the process corresponding to the ejection of three neutrons also occurred thus producing ${\mathrm{Sc}}^{43}$ of half-life 4 hours and ${\mathrm{Sc}}^{44}$ of half-life 53 hours from the stable ${\mathrm{Sc}}^{45}$. By varying the energy of the incident neutrons and observing the ratio of the two radioactivities produced, it now appears that these two activities are due to isomers of ${\mathrm{Sc}}^{44}$. Hence there is no definite evidence as yet for the loss of three neutrons from the excited nucleus. Although scandium has but one stable isotope (${\mathrm{Sc}}^{45}$) there appears to be eight radioactive periods, six of which can be assigned with reasonable certainty to various scandium isotopes. The excitation function for the ejection of two neutrons is studied by observing the radioactivity produced at various energies of the incident neutrons. There is evidence of anomalous behavior for certain elements.