A Proton-Gamma-Ray Coincidence Study ofSi30andB11

The excited states of the ${\mathrm{Si}}^{30}$ and ${\mathrm{B}}^{11}$ nuclei were studied by means of a proton-gamma-ray coincidence technique for the purpose of determining the nature of the gamma-ray decay scheme. The nuclei were formed under cyclotron bombardment using the ${\mathrm{Al}}^{27}(\alpha ,p){\mathrm{Si}}^{30}$ and ${\mathrm{B}}^{10}\mathrm{}(d,p)\mathrm{}{\mathrm{B}}^{11}$ reactions. The transitions from the first two excited states of ${\mathrm{Si}}^{30}$ are directly to the ground state, while the transition from the third excited state takes place by means of a cascade to the second state and then to the ground state. The decay scheme in the ${\mathrm{B}}^{11}$ nucleus is most likely the same as for the ${\mathrm{Si}}^{30}$ nucleus for the first two excited states, while the third and the prolific fifth and sixth states show cascade transitions as most probable.