Angular Distributions and Total Cross Sections of Charged Particles fromLi6+Li6as a Function of Energy

Abstract

The ${\mathrm{Li}}^6$+${\mathrm{Li}}^6$ reaction has been studied at 13 incident energies between 2.4 and 9.0 MeV, using a $\frac{\mathrm{dE}}{\mathrm{dx}}-E$ particle identification system and an on-line computer. Total cross sections and angular distributions were obtained for protons from the first 12 levels of ${\mathrm{B}}^{11}$, deuterons from the first 5 $T=0\mathrm{}$ levels in ${\mathrm{B}}^{10}$, and tritons from the ${\mathrm{B}}^9$ ground state. Noticeable variations in the proton angular distributions as a function of bombarding energy and indications of a ($2J+1$) dependence of the proton cross sections as the bombarding energy was increased are indicative of compound nucleus effects. On the other hand, in the deuteron results, the dominant reaction mechanism is the transfer of an alpha particle. This process is favored for the residual states which are formed by $l_{\alpha }=0\mathrm{}$ transfer. There is no evidence for strong structure in the yield curves for the deuteron groups from one energy to the next. Simple considerations of the transfer as a tunneling process, possibly modified by the presence of a long-range effective interaction, adequately describe the deuteron cross sections. Measurements were made on the ground-state deuteron group at a bombarding energy corresponding to measurements on the inverse reaction, ${\mathrm{B}}^{10}(d, {\mathrm{Li}}^6){\mathrm{Li}}^6$, and the angular distribution and total cross section are in good agreement. The differential cross-section ratio of the 16.62- to 16.92-MeV levels in the ${\mathrm{Li}}^6({\mathrm{Li}}^6, \alpha ){\mathrm{Be}}^8$ reaction was also measured and found to be 1.20±0.10 and constant as a function of ${\mathrm{Li}}^6$ energy.