  We have investigated beating patterns in Shubnikov-de Haas oscillations for
HgTe/Hg_{0.3}Cd_{0.7}Te(001) quantum wells with electron densities of 2 to 3 X
10^{12} cm^{-2}. Up to 12 beating nodes have been observed at magnetic fields
between 0.9 and 6 T. Zero magnetic field spin-orbit splitting energies up to 30
meV have been directly determined from the node positions as well as from the
intersection of self-consistently calculated Landau levels. These values, which
exceed the thermal broadening of Landau levels, k_B T, at room temperature, are
in good agreement with Rashba spin-orbit splitting energies calculated by means
of an 8 X 8 kp Kane model. The experimental Shubnikov-de Haas oscillations are
also in good agreement with numerical simulations based on this model.
