Four-body ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$(α,2α)pn breakup cross sections were measured from 77 to 119 MeV. Spectral functions S for k=0.1 ${\mathrm{fm}}^{\mathrm{-}1}$ (where ħk is the p-n relative momentum) were deduced. Those obtained from the 89 to 119 MeV data are internally consistent, and agree with the k dependence of S found in earlier studies of the (α,2α)pn and (p,pα)pn reactions on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$. However, the S found at 77 MeV was low, which may indicate distortion effects. Throughout this energy region, the four-body breakup cross section at low p-n excitation follows the α-α elastic scattering cross section as the latter changes by a factor of 50, showing that quasifree scattering is the dominant process.

• Received 9 March 1992

DOI:https://doi.org/10.1103/PhysRevC.46.616