  A measurement of the polarization of Lambda and Anti-Lambda baryons produced
in pC and pW collisions at sqrt(s)=41.6 GeV has been performed with the HERA-B
spectrometer. The measurements cover the kinematic range of 0.6 GeV/c < p_T<1.2
GeV/c in transverse momentum and -0.15<x_F<0.01 in Feynman-x. The polarization
results from the two different targets agree within the statistical error. In
the combined data set, the largest deviation from zero, +0.054 +- 0.029, is
measured for x_F < -0.07. Zero polarization is expected at x_F=0 in the absence
of nuclear effects. The polarization results for the Lambda agree with a
parametrization of previous measurements which were performed at positive x_F
values, where the Lambda polarization is negative. Results of Anti-Lambda
polarization measurements are consistent with zero.
