HE-4 INDUCED LI-6-]ALPHA+D TARGET BREAKUP IN THE REGION OF SMALL RELATIVE FRAGMENT ENERGIES

The Li-6(alpha, alpha') reaction has been studied at E(alpha) = 40 MeV . The angular distribution of the continuum region near the Li-6 --> a lpha+d breakup threshold (1.475 MeV) was measured for theta(lab) = 10- degrees-32-degrees. The data exhibit a lowering in cross section at th e forward angle region where the quasifree breakup model calculations fail to explain the data. Rom the Li-6(alpha, alpha') data at E(alpha) = 50 MeV and the Li-6(p,p) data at E(p) = 65 and 80 MeV we found that the breakup cross section drops below a critical momentum transfer (a pproximately 117 MeV/c). The 40 MeV data reaffirm our earlier finding. The above critical value of the momentum transfer seems to play a cru cial role both in the target and projectile breakup reactions and migh t be useful in determining the onset of the Coulomb dissociation.