REACTION CROSS-SECTION MEASUREMENTS OF THE NEUTRON-RICH ISOTOPES LI-8,LI-9,LI-11, AT 80 MEV NUCLEON

Total interaction cross sections have been measured for Li-8 on C and Pb targets, for Li-9 on C, Al, Cu, Sn and Pb targets as well as for Li-11 on C, Sn and Pb targets. For each beam, we also used a plastic scintillator as target. The measurements with the scintillator targets are used to extract reduced nuclear radii of the lithium isotopes. These radii are then used for the calculation of the nuclear part of the total cross section for the other targets. The total electromagnetic-dissociation (EMD) cross sections have been deduced and are compared to different models. A strong target-charge-dependent EMD cross section is measured for Li-11 reaching 2.96(-0.82)+0.84b for the Pb target. In the Li-9 case, a large EMD cross section for high-Z targets has been observed which amounts to 0.75 +/- 0.45b for the Pb target. The EMD cross sections of both, Li-9 and Li-11, may be understood by the giant-dipole-resonance model.