Electron-gamma PAC: New possibilities for NQI studies

The application of hyperfine interaction techniques to problems in solid st ate physics has been steadily growing over the last decade with the use of radioactive ion beam facilities such as ISOLDE at CERN. New applications of the e(-)-gamma Perturbed Angular Correlation (PAC) technique are underway at ISOLDE using probe nuclei with highly converted cascades. In this paper we present the motivation for extending PAC experiments to elements/isotope s not usable with the conventional gamma-gamma PAC technique. Examples will be shown where the long-lived As-73/Ge-73, the short lived Ba-127/Cs-127 a nd the Hg-197m/Hg-197 decay cascades are applied to measurements of nuclear quadrupole interactions in materials.