  Angular momentum dependences of the parity splitting and electric dipole
transitions in the alternating parity bands of heavy nuclei have been analyzed.
It is shown that these dependences can be treated in a universal way with a
single parameter of critical angular momentum, which characterizes phase
transition from octupole vibrations to the stable octupole deformation. Using
the simple but useful model of axially-symmetric reflection-asymmetric mode,
the analytical expression for the parity splitting and electric dipole
transitional moment have been obtained. The results obtained are in a good
agreement with the experimental data for various isotopes of Ra, Th, U, and Pu.
