Abstract:
Recent investigations of heavy-ion reactions at low incident energies have indicated the presence of
precompound emission component in considerable strength. In most cases the strength of the precompound
component is estimated from the difference in forward-backward distributions of emitted light fast particles and
also from the analysis of the measured excitation functions. This paper reports a new method of deciphering
the relative contributions of compound and precompound components associated with fusion of 16O with 159Tb, 169Tm, and 181Ta targets by measuring the recoil ranges of heavy residues in an absorbing medium along with
the online measurement of the spin distributions in reaction residues produced in the fusion 16O beam with 159Tb and 169Tm targets. Analysis of recoil range and spin distributions of the residues shows two distinct linear
momentum-transfer components corresponding to precompound and compound nucleus processes. The input
angular momentum associated with precompound products is found to be relatively lower than that associated
with compound nucleus process. The precompound components obtained from the present analysis are consistent
with those obtained from the analysis of excitation functions.
