  Based on multiyear INTEGRAL observations of SS433 in 2003-2011, a composite
IBIS/ISGRI 18-60 keV orbital light curve is constructed around zero
precessional phases psi_{pr}= 0 at the maximim accretion disk opening angle. It
shows a peculiar shape with significant excess near the orbital phase phi_orb=
0.25, which is not seen in the softer 2-10 keV energy band. The 40-60 keV
orbital light curve demonstrates two almost equal humps at phases \sim 0.25 and
\sim 0.75, most likely due to nutation effects of the accretion disk. The
nutational variability of SS433 in 15-50 keV with a period of 6.290 days is
independently found from timing analysis of Swift/BAT data. The change of the
off-eclipse 18-60 keV X-ray flux with the precessional phase shows a
double-wave form with strong primary maximum at psi_{pr}= 0 and weak but
significant secondary maximum at psi_{pr}= 0.6. A weak variability of the 18-60
keV flux in the middle of the orbital eclipse correlated with the disk
precessional phase is also observed. The joint analysis of the broadband 18-60
keV orbital and precessional light curves confirms the presence of a hot
extended corona in the central parts of the supercritical accretion disk and
constrains the binary mass ratio in SS433 in the range 0.5>q>0.3, suggesting
the black hole nature of the compact object.
