  Inclusive cross sections $\sigma^A=Ed^3{\sigma(X,P_t^2)/d^3p}$ of antiproton
and negative pion production on Be, Al, Cu and Ta targets hit by 10 GeV protons
were measured at the laboratory angles of 10.5$^{\circ}$ and 59$^{\circ}$.
Antiproton cross sections were obtained in both kinematically allowed and
kinematically forbidden regions for antiproton production on a free nucleon.
The antiproton cross section ratio as a function of the longitudinal variable
$X$ exhibits three separate plateaus which gives evidence for the existence of
compact baryon configurations in nuclei-small-distance scaled objects of
nuclear structure. Comparability of the measured cross section ratios with
those obtained in the inclusive electron scattering off nuclei suggests a weak
antiproton absorption in nuclei. Observed behavior of the cross section ratios
is interpreted in the framework of a model considering the hadron production as
a fragmentation of quarks (antiquarks) into hadrons. It has been established
that the antiproton formation length in nuclear matter can reach the magnitude
of 4.5 fm.
