Spectroscopic investigations of highly deformed nuclei in the mass similar to 80 and similar to 140 regions

Four in-beam gamma-ray spectroscopy experiments were conducted to investigate the properties of highly deformed nuclei in the ∼80 and ∼140 mass regions. These nuclei have a 2:1 major-to-minor axis ratio, and commonly are referred to as superdeformed nuclei. The Gammasphere gamma-ray spectrometer, and the Microball charged-particle detector array, were used to detect the gamma-ray and charged-particle emissions. Employing Doppler-shift attenuation analyses, a comparative measurement is obtained of the transition quadrupole moments (Qt) of the superdeformed rotational bands in 80--83Sr, 82--84Y and 83,84Zr. The results from these measurements establish for the first time, accurate trends in the deformations associated with these band structures as a function of neutron number (N) and proton number (Z). Additionally, the dynamic moments of inertia and the feeding and decay patterns of these superdeformed bands are examined to aid in clarifying the structure of these highly deformed nuclei. The high accuracy of the measured Qt values of these bands enables a stringent comparison with values derived from theoretical interpretations of these nuclear states. These interpretations indicate that fewer high-j, h11/2 intruder orbitals are occupied in the underlying structure of some of these bands than was presumed in previous works. The study on mass ∼140 nuclei allowed an exhaustive search for the linking gamma-ray decays out of the superdeformed band in 143Eu. Spectra in coincidence with the yrast superdeformed band in 143Eu were produced to search for previously reported two-step transitions from superdeformed to near-yrast, normally-deformed levels in 143 Eu. However, the two-step decay-out of the superdeformed band in 143Eu was not observed. This result is significant in that it eliminates the only reported case in the ∼140--150 mass region in which links to the underlying normally deformed level structure were claimed. Searches for single step decays revealed several high-energy photopeaks which are tentatively identified as single-step decays from the superdeformed band in 143 Eu. A search for other superdeformed structures revealed several new superdeformed bands in 142--144Eu. The transition energies and dynamic moments of inertia of these bands, as well as those of previously observed superdeformed bands in 142--144Eu are reported.