Analysis of 200 MeV polarized proton scattering from 58Ni

Data has been taken at the Indiana University Cyclotron Facility (IUCF) on 200 MeV polarized proton scattering on 58Ni. The data cover the scattering angles of 8 to 65 degrees with an excitiation energy of 0 to about 15 MeV. The resolution of this experiment for the scattered protons is about 25 keV. There are are variety of physics questions being addressed with this data.

1. Neutron transition densities

Using charge transition densities obtained from electron scattering we have obtianed neutron transition densities for four 2+, one 3- and five 4+ states. These were obtained using the code LEA and employing an empirical effective interaction at 200 MeV.

A paper is in progress with the first draft finished and some remaining calculations to be done to finish it. It is hoped that this project will be finished by the end of the summer of 1997.

2. Location of isoscalar strength

The purpose of this work is to identifiy as many as possible states in the spectra and then analyzed them using a collective model deformed potential in the code ECIS in order to identify all the isoscalar strength. These results can be compared to RPA calculations and can also be used with giant resonance strength to determine if all of the sum rule strength has been depleted. One topic of this work is to determine what is really meant by an isoscalar state.

3. 6+ states

Examine all the 6+ states in comparison to electron scattering. The 6+ state at 5.12 MeV has been determined to be mainly excited by the isoscalar spin orbit force we might be able to use this state to examine this force.

4. 8- states

We have located a variety of 8- states which have also been observed with electron scattering. Using the electron scattering to determine the structure of these states we may be able to examine the tensor force in the nucleus. Recent work has shown that this force is effected by in medium effects, mainly those due to the reduced mass of the rho meson in nuclear media.