Tunneling along gamma-axis between prolate and oblate shapes

Using Zickendraht - Dzyublik - Filippov coordinates; we derived equation to determine the rotation and monopole + quadrupole vibrations of the nuclear ellipsoid of inertia. Apart from the monopole part, it coincides with the Bohr - Mottelson equation. However, our mass parameter turns out to be about 2.5 times larger than the hydrodynamic one. The equation is solved quasi-classically for nonrotating beta rigid but gamma soft nuclei, whose energy landscape has prolate and oblate minima, connected by the collective path along the gamma axis. The gamma tunnelling strength appears to be twice the usual one, taking place for the one-dimensional potential with two minima, separated by the barrier. The E0 transition strength between levels of the ground 0+ doublet is calculated. The results are consistent with the experiment for 74Kr