Quantum Phase Transitions in Odd-Mass Nuclei
Quantum shape-phase transitions in odd-even nuclei are investigated in the framework of the interacting boson-fermion model. Classical and quantum analysis show that the presence of the odd fermion strongly influences the location and nature of the phase transition, especially near the critical point. Experimental evidence for the occurrence of spherical to axially-deformed transitions in odd-proton nuclei Pm, Eu and Tb (Z=61, 63, 65) is presented. Quantum phase transitions (QPTs) are qualitative changes in the ground state properties of a physical system induced by a variation of parameters in the quantum Hamiltonian. These structural modifications have found a variety of applications in diverse areas of physics. 1 One of these applications is to atomic nuclei, where QPTs in even-even nuclei have been extensively investigated (for a review, see 2–4 ) within the framework of the Interacting Boson Model (IBM), 5 a model of nuclei in terms of correlated pairs of valence nucleons with L = 0,2 treated as (s,d) bosons. 5 In the present contribution we extend these studies to odd-even nuclei making use of the Interacting Boson Fermion Model (IBFM), 6 incorporating an additional unpaired fermion with angular momentum j. The reported results