Phase Transitions in Gauge Space: A Study within a Superfluid Model of Atomic Nucleus Including Pairing and alpha Type Correlations.

摘要

By including an adequate four-particle interaction in addition to the pairing interaction, correlations between proton and neutron fluids in deformed nuclei are induced. As a result, superfluidities of the two nuclear systems may be generated by one another and the phase structure is enriched by a new superfluid phase dominated by alpha type correlations at zero and finite temperature. The finite temperature BCS gap and Fermi energies equations have been derived by minimizing the grand thermodynamic potential (the Gibbs free energy). These equations have the same form both for the finite temperature and for the zero temperature. The only difference between T not =0 and T=0 cases is the presence of nonzero quasiparticle occupations when Tnot =0. Assuming that the single particle spectra of the Hamiltonian are identical and equidistant for protons and neutrons and also the pairing properties are the same we have shown that: 1) ''first and second order phase transitions'' from superfluid states to normal fluid states are caused by raising the temperature; 2) there is another two critical temperature in addition to the known one, corresponding to the new ''alpha-like'' superfluid phase and 3) the probabilities of some processes as e.g. alpha clusterization are significantly modified in some cases. (author). 15 refs, 11 figs. (Atomindex citation 19:091125)