Particle Groups from the Bombardment of Aluminum by Deuterons

Targets of aluminum leaf 30 kev thick have been bombarded by deuterons and found to emit protons in 14 groups and alpha-particles in four groups. These correspond to levels in ${\mathrm{Al}}^{28}$ and ${\mathrm{Mg}}^{25}$. The level spacing in ${\mathrm{Al}}^{28}$ appears to become somewhat less at excitation energies of 5 Mev, and the population of the highly excited states is greater. There appear to be five major groupings, each having a finer structure. Observation at 90° and 0° with respect to the incident deuterons shows a considerable variation in relative yield. In comparison with neutron scattering levels for the same nucleus, the spacing here observed is greater. This may be due to the adverse selection of groups of high angular momentum on account of the Coulomb barrier. The level spacing in ${\mathrm{Mg}}^{25}$ is approximately 0.8 Mev. From the maximum energy of the protons and alpha-particles the mass difference between ${\mathrm{Al}}^{28}$ and ${\mathrm{Al}}^{27}$ is found to be 1.00073±0.00008, and between ${\mathrm{Mg}}^{25}$ and ${\mathrm{Al}}^{27}$ is 1.99619±0.00006 mass units.