The Fifth Conference “ Nuclear Science and Its Application”, 14-17 October 2008
HIGH-SPIN PHYSICS IN THE FERMION DYNAMICAL SYMMETRY
MODEL
K. BAKTYBAYEV
Almaty, Kazakhstan al-Farabi University
It would be desirable to have a microscopic theory of high-spin nuclear structure based entirely on the spherical shall model with effective nucleon-nucleon interactions. Experiments are now routinely done yielding detailed spectroscopy of states in the range I/h~3 5-*-45. An attractive possibility is to exploit dynamical symmetries to allow solutions of complicated many-body problem. High-spin physics exhibits an exquisite interweaving of collective (bosonic) and single- particle (fermionic) degrees of freedom. The most ambitions application of dynamical symmetries in heavy nuclei in the interacting boson model (IBM). However, this model is not designed to describe high-spin phenomena in its simplest implementation.
In this work we present a group-theoretical solution to the spherical shell model which describes a broad range of high-spin physics. It is described a model which yield the basic features of high-spin physics by exploiting dynamical fermion symmetry to truncate the spherical shell model. This is particularly interesting since the model was not explicitly constructed to yield such phenomena. Indeed, the SU(3) limit is only one of several dynamical symmetries which appear on an equal footing within the model, and which are known to occur systematically in low-energy nuclear structure. Thus an algebraic synthesis o f high-spin and low-spin physics is implicit in this work. These results indicate that a microscopic calculation of high-spin structure is feasible starting from the spherical shell model without explicit introduction of bosons, deformations, pah-fields, or Coriolis forces. It is shown that the model is capable of describing rotation, p and y - bands, coriolis antipairing, rotation alignment, multiple band crossings and associated backbends. It gives a much better description of high-spin M(E2) values than algebraic boson model.
