  A method for measuring the tensor polarization in a positronium (Ps) beam is
proposed, which is based on the determination of the Ps lifetime as a function
of the orientation of a homogeneous magnetic field. The dependence of the
orthopositronum (o-Ps) lifetime on the angle between the directions of the
magnetic field and the tensor polarization of the Ps beam can be determined
from the results of measurements from two or more field orientations.
