MEASUREMENT AND THEORETICAL-ANALYSIS OF NEUTRON ELASTIC-SCATTERING AND INELASTIC REACTIONS LEADING TO A 3-BODY FINAL-STATE FOR LI-6 AT 10 TO 20 MEV

The neutron elastic and inelastic scattering double-differential cross sections of Li-6 were measured at incident neutron energies of 11.5, 14.1, and 18.0 MeV. A phenomenological neutron optical model potential of Li-6 was constructed to describe the total and elastic scattering cross sections from 5 MeV to several tens MeV, based on the present da ta together with information from other works. This potential was foun d to describe the inelastic scattering to the first excited state (E-x =2.186 MeV) well via the distorted-wave Born approximation (DWBA) calc ulation with the macroscopic vibrational model. The continuum neutron energy spectra and angular distributions were then analyzed by the the ory of final-state interaction extended to the DWBA form, with an assu mption that the d-alpha interaction is dominant in the three-body fina l state consisting of n, d, and alpha particles. Such a calculation wa s found to be successful in explaining the major part of the low-excit ation neutron spectra and angular distribution down to the Q-value reg ion of - 9 MeV, except for the Q-value range where the n-alpha quasifr ee scattering will give a non-negligible contribution at forward angle s. [S0556-2813(98)04810-9].