MOMENTUM DISTRIBUTIONS OF LI-9 FRAGMENTS FOLLOWING THE BREAKUP OF LI-11

Using a fragment separator as an energy-loss spectrometer the parallel momentum distributions of Li-9 nuclei produced in the breakup of Li-11 at 66 MeV/nucleon have been measured. Distributions with Gaussian widths of sigma(parallel-to) almost-equal-to 19 MeV/c were observed for Be-9, Nb-93, and Ta-181 targets-the first time such a narrow structure has been observed for high mass targets. From the weak dependence of width on breakup target it appears that the parallel momentum distributions are relatively insensitive to the interaction governing the breakup and reflect an extended neutron distribution for Li-11.