  The $dd\to ^3He n$ reaction is considered at the energies between 200 MeV and
520 MeV. The Alt-Grassberger-Sandhas equations are iterated up to the lowest
order terms over the nucleon-nucleon t-matrix. The parameterized ${^3He}$ wave
function including five components is used. The angular dependence of the
differential cross section and energy dependence of tensor analyzing power
$T_{20}$ at the zero scattering angle are presented in comparison with the
experimental data.
