Measurement of the vector analysing power in the πd‐breakup

The vector analysing power, iT11, has been measured for the π+d → π+pn reaction in a kinematically complete experiment. The dependence of iT11 on the momentum of the proton has been obtained for 35 pion‐proton angle pairs at pion bombarding energies of 180 MeV, 228 MeV and 294 MeV. The data are compared with a relativistic Faddeev calculation.