## EPSRC Visiting Fellow |

** **

**Alex Brown of Michigan State University spent six months of his sabbatical
leave as an EPSRC Visiting Fellow with the nuclear orientation group
of Nick Stone at Oxford. As an experienced nuclear shell model theorist,
Brown's objectives were to set up detailed calculations in the ^{132}Sn
region to support interpretation of new magnetic dipole moment and decay
data obtained by the Oxford group in recent nuclear orientation on-line
studies at the OSIRIS facility, Studsvik in Sweden. Brown's other purpose
was to work with Jirina Stone on testing the new Skyrme skx interaction
using Hartree Fock models**

**In the work at ^{132}Sn, Brown set up a basis for large scale
shell model calculations in the model space where the neutrons fill the
top of the (0g_{7/2},1d_{5/2},1d_{3/2},2s_{5/2},Oh_{11/2})
shell and protons fill the bottom of this shell. A new G matrix hamiltonian
to deal with proton-neutron interaction was developed in collaboration
with N. Hjorth-Jensen of Oslo to complement existing proton-proton and
neutron-neutron interactions.**

**Alex Brown collaborated with Ian Towner on full calculations of single-particle
nuclear magnetic dipole moments based on his shell model wavefunctions.
These calculations provide the basis for interpretation of new magnetic
moment, excited state and transition properties of Sb, Te, Xe and I isotopes
resulting from the work of the Oxford nuclear orientation group at the
Studsvik laboratory. First papers have been written and the project is
ongoing. Nuclear theory hand-in-hand with experiment in this region is
vitally important in allowing extraction of sub-nucleon degrees of freedom
(mesonic exchange current effects) from precisely measured nuclear dipole
moments.**

**The 'pure theory' research concentrated on testing the SkX
Skyrme interaction in predictions of properties of infinite isoscaler nuclear
matter and pure neutron matter. This took the form of exploring the feasibility
of making calculations on neutron stars (with density up to ten times that
of nuclei) using the same interaction as that found acceptable in describing
nuclei. This essential compatibility was shown to exist but to impose useful
constraints on the theory. A second aspect of this work was an investigation
of how nuclear radii calculated in spherical and deformed HF models compared
with each other and with experiment. Both projects are on-going and will
be published soon**

**During his time in the United Kingdom Brown gave invited seminars
and colloquia at Universities of Liverpool, Manchester, Oxford and Surrey.
He worked closely with graduate students of the nuclear orientation group.
His detailed predictions of structure of Sb, Te, I and Xe isotopes will
enhance a whole generation of theses!**