Thomas Socci, Yale UniversityTitle: High-Spin States in AstatineAuthors: T. Socci, C.W. Beausang, J. Novak (Yale University)Abstract: High-spin states in astatine isotopes near mass 200 have been investigated using the YRAST Ball array of Yale University's Wright Nuclear Structure Laboratory. The YRAST Ball array, with a total photo-peak efficiency of almost 2%, consisted of 19 Compton-suppressed Ge detectors of 25% relative efficiency, one Compton-suppressed 75% Ge detector and 3 segmented Clover Ge detectors of 150% relative efficiency. The reaction 197Au(13C,xn) at beam energies between 70 and 90 MeV was used to populate high-spin states in 204-206At. Before this experiment only one excited state was known in doubly-odd 204At. Excitation function yields, together with x-ray and gamma-ray coincidences have been used to assign gamma-rays to particular At nuclei. Cascades of gamma rays are being constructed from a gamma-gamma coincidence matrix in order to piece together the level schemes. An angular correlation study of the data is being performed to determine the dipole or quadrupole nature of the transitions. The data is currently being analyzed and recent results will be presented. |