  We investigate the polarization parameters in low-energy antiproton-proton
elastic ($\bar{p}p\rightarrow\bar{p}p$) and charge-exchange
($\bar{p}p\rightarrow\bar{n}n$) scattering. The predictions for unmeasured
observables are based on our new energy-dependent partial-wave analysis of all
antiproton-proton scattering data below 925 MeV/$c$ antiproton laboratory
momentum, which gives an optimal description of the existing database. Sizable
and remarkable spin effects are observed, in particular for charge-exchange
scattering. These result from the spin dependence of the long- and medium-range
one- and two-pion exchange antinucleon-nucleon potential and the state
dependence of the parametrized short-range interaction. We study the
possibility of polarizing a circulating antiproton beam with a polarized proton
target by exploiting the spin dependence of the $\bar{p}p$ total cross section.
It appears feasible to achieve a significant transverse polarization of an
antiproton beam within a reasonable time.
