Particle Groups from the Alpha-Particle Bombardment of Boron

Targets of natural boron and targets of 96 percent boron 10 have been bombarded by 7.45 Mev and 6.64 Mev cyclotron alphas. Seven charged particle groups have been observed. The $Q$-values calculated from the energy of the various groups have been assigned as follows: $Q_1=4.07\mathrm{}$ Mev to the ${\mathrm{B}}^{10}\mathrm{}(a,p)\mathrm{}{\mathrm{C}}^{13}$ reaction; $Q_2=0.85\mathrm{}$ Mev to the ${\mathrm{B}}^{11}\mathrm{}(a,p)\mathrm{}{\mathrm{C}}^{14}$ reaction; $Q_3=0.31\mathrm{}$ Mev to the first excited state of carbon 13 at 3.76 Mev. Other values are: $Q_4=0.07\mathrm{}$ Mev; $Q_5=-0.31\mathrm{}$ Mev; $Q_6=-1.57\mathrm{}$ Mev; $Q_7=-1.76\mathrm{}$ Mev with assignments discussed. The assignments were checked with boron 10 targets and proton-gamma-coincidence technique. Gammas were detected by coincident counts from two photo-multiplier tubes observing the same naphthalene crystal. Excited states of carbon 13 were searched for, but not observed, at 0.8 Mev and 3.12 Mev.