What do the tensor analyzing powers say about the phase of the coupling potentials

The Tensor Analyzing Powers for the reaction /sup 7/Li + /sup 120/Sn at 44 MeV are studied in a coupled channels formalism. The states considered are the 3/2/sup -/, 1/2/sup -/, 7/2/sup -/ and 5/2/sup -/ in /sup 7/Li, that are described as (Os)/sup 4/(Op)/sup 3/ configurations with the maximum spatial symmetry. The diagonal and transition potentials are obtained by folding the M3Y effective interaction with the nuclear densities. They are multiplied by a complex factor (1 + 0.6i) to obtain the imaginary parts. It is found that the elastic and inelastic cross sections are well reproduced. The elastic rank-2 Analyzing Powers are overestimated, possibly due to the choice of the same geometry for real and imaginary potentials. The inelastic rank-2 Analyzing Powers are consistent with the PWBA calculation. The inelastic rank-1 Analyzing Powers are grossly underestimated. This seems to be an indication of other mechanisms to excite the 1/2- state different of a tensor force of the T(R-vector) type. When the calculation is performed only with real coupling potentials, the inelastic coupling potentials are reduced, and the interference with the Coulomb potential is more severe. The elastic rank-1 Analyzing Powers are qualitatively affected, so that the angle at which they become negative is increased. In both cases, the agreement with experiment is worse. The other observables are not affected very much. The dependence of the Tensor Analyzing Powers obtained in the coupled channels calculation with the phase of the coupling can be understood in a DWBA formalism. It is suggested that the elastic rank-1 Analyzing Powers can be a direct measure of the phase of the coupling potentials