Three-body effects in the /sup 7/Li (/ital d/,. cap alpha cap alpha. /ital n/) reaction

Measurements of the differential cross sections for the/sup 7/Li(/ital d/,..cap alpha cap alpha..n) reaction have been performed at deuteron incident energy /ital E/(/ital d/)=6.8 MeV. The kinematical configurations were chosen so as to optimize the population of the /sup 5/He/sup **/ 3/2/sup +/ state with 16.76 MeV excitation energy. The parameters of this resonance are deduced from the experimental data; deviations from the standard values indicate the relevance of three-body effects and/or rescattering. Some phenomenological considerations give a qualitative explanation of the results obtained. In particular, as far as the width is concerned, we observe a broadening with respect to the standard value, which may be related to the presence of a shadow pole.