A three crystal pair spectrometer was used to determine the relative intensities of gamma radiation produced in the bombardment of separated ${\mathrm{Li}}^6$ and ${\mathrm{Li}}^7$ targets by ${\mathrm{Li}}^6$ and ${\mathrm{Li}}^7$ ions at energies of 2.6 and 3.6 MeV. The observed gamma radiation arises from excited states of residual nuclei. These include ${\mathrm{Be}}^{10}$, ${\mathrm{B}}^{10}$, ${\mathrm{B}}^{11}$, ${\mathrm{B}}^{12}$, ${\mathrm{B}}^{13}$, ${\mathrm{C}}^{11}$, and ${\mathrm{C}}^{12}$ in the present experiment. Relative populations deduced from the data indicate that a difference of one unit of charge for the matter transferred in the reaction does not strongly influence the relative cross sections. In particular, the production of ${\mathrm{B}}^{12}$ (ground state) and the equivalent state in ${\mathrm{C}}^{12}$ (15.11 MeV) in the bombardment of ${\mathrm{Li}}^7$ by ${\mathrm{Li}}^6$ were in the ratio 2:1. A value of 2.3:1 is predicted for this ratio on the basis of simple stripping theory and cluster breakup in this reaction. The relative populations of the excited states of ${\mathrm{B}}^{11}$ produced in the three reactions show systematic variations as a function of excitation.

• Received 31 May 1962

DOI:https://doi.org/10.1103/PhysRev.128.247