2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/182087Exact solutions of the Bohr Hamiltonian with a five-dimensional square well potential, in isolation or coupled to a fermion by the five-dimensional spin-orbit interaction, are considered as examples of a new class of dynamical symmetry or Bose-Fermi dynamical symmetry. The solutions provide baselines for experimental studies of even-even [E(5)] and odd-mass [E(5|4)] nuclei near the critical point of the spherical to deformed gamma-unstable phase transition.LaTeX (elsart), 53 pages; typographical correction to (3.15)Nuclear Theorytext