Energy dependence of the 6Li( alpha,2 alpha )pn reaction from 77 to 119 MeV.

Abstract

Four-body $^{6}\mathrm{Li}$(\ensuremath{\alpha},2\ensuremath{\alpha})pn breakup cross sections were measured from 77 to 119 MeV. Spectral functions S for k=0.1 ${\mathrm{fm}}^{\mathrm{\ensuremath{-}}1}$ (where \ensuremath{\Elzxh}k 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 (\ensuremath{\alpha},2\ensuremath{\alpha})pn and (p,p\ensuremath{\alpha})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 \ensuremath{\alpha}-\ensuremath{\alpha} elastic scattering cross section as the latter changes by a factor of 50, showing that quasifree scattering is the dominant process.