Measurement of the polarization in the reaction π-+p → π0+n in the interval 0< Vertical Bar t Vertical Bar <2 (GeV/c) at 40 GeV/c

Measurements of the polarization in the reaction π-p → π0n are reported for the interval 0< Vertical Bar t Vertical Bar <2 (GeV/c)2 at the momentum 40 GeV/c. The polarization is positive at Vertical Bar t Vertical Bar <0.4 (GeV/c)2. In the ''crossover'' region of elastic π+-p scattering, evidence is found for a minimum in the polarization (this is the first such evidence). The polarization near this point is compatible with a value of zero, within the experimental errors. Near the dip in the differential cross section for charge exchange, the polarization is negative. These results are at odds with published theoretical predictions