Ponencias (Física Atómica, Molecular y Nuclear)
https://hdl.handle.net/11441/10866
2019-07-24T03:23:08ZProbing 6He structure from proton inelastic collisions
https://hdl.handle.net/11441/85009
Probing 6He structure from proton inelastic collisions
We explore the Hyperspherical Harmonics pseudostate method to describe the 6He continuum. The method is use it within the multiple scattering of the transition amplitude (MST) approach to study inelastic scattering of p-6He at 700 MeV/u.
2006-01-01T00:00:00ZOn the relation between E(5)- models and the interacting boson model
https://hdl.handle.net/11441/84883
On the relation between E(5)- models and the interacting boson model
The connections between the Ε(5)-models (the original Ε(5) using an infinite square well, Ε(5) - β4 Ε(5) - β6 and Ε(5) - β8), based on particular solutions of the geometrical Bohr Hamiltonian with γ -unstable potentials, and the interacting boson model (IBM) are explored. For that purpose, the general IBM Hamiltonian for the U(5) - O(6) transition line is used and a numerical fit to the different £(5) - models energies is performed. It is shown that within the IBM one can reproduce very well all these Ε(5) - models. The agreement is the best for Ε(5) - β4 and reduces when passing through Ε(5) - β6, Ε(5) - β8 and Ε(5), where the worst agreement is obtained (although still very good for a restricted set of lowest lying states). The fitted IBM Hamiltonians correspond to energy surfaces close to those expected for the critical point.
2009-01-01T00:00:00ZShape phase transitions and critical points
https://hdl.handle.net/11441/84881
Shape phase transitions and critical points
We investigate different aspects connected with shape phase transitions in nuclei and the possible occurrence of dynamical symmetries at the critical points. We discuss in particular the behaviour of the neighbour odd nuclei at the vicinity of the critical points in the even nuclei. We consider both the case of the transition from the vibrational behaviour to the gamma-unstable deformation (characterized within the collective Bohr hamiltonian by the E(5) critical point symmetry) and the case of the transition from the vibrational behaviour to the stable axial deformation (characterized by the X(5) symmetry). The odd particle is assumed to be moving in the three single particle orbitals j=1/2,3/2,5/2, a set of orbitals that is known to lead to possible supersymmetric cases. The coupling of the odd particle to the Bohr hamiltonian does lead in fact in the former case at the critical point to the E(5/12) boson-fermion dynamical symmetry. An alternative approach to the two shape transitions is based on the Interacting Boson Fermion Model. In this case suitably parametrized boson-fermion hamiltonians can describe the evolution of the odd system along the shape transitions. At the critical points both energy spectra and electromagnetic transitions were found to display characteristic patterns similar to those displayed by the even nuclei at the corresponding critical point. The behaviour of the odd nuclei can therefore be seen as necessary complementary signatures of the occurrence of the phase transitions.
2009-01-01T00:00:00ZDecoherence as a Signature of an Excited State Quantum Phase Transition in Two Level Boson Systems
https://hdl.handle.net/11441/84830
Decoherence as a Signature of an Excited State Quantum Phase Transition in Two Level Boson Systems
We analyze the decoherence induced on a single qubit by the interaction with a two-level boson system with critical internal dynamics. We explore how the decoherence process is affected by the presence of quantum phase transitions in the environment. We conclude that the dynamics of the qubit changes dramatically when the environment passes through a continuous excited state quantum phase transition. If the system-environment coupling energy equals the energy at which the environment has a critical behavior, the decoherence induced on the qubit is maximal and the fidelity tends to zero with finite size scaling obeying a power-law.
2009-01-01T00:00:00Z