Structure of neutron-rich nuclei and neutron multiplicities in spontaneous fission

New insights into the fission process and the structure of neutron-rich nuclei have been gained by measuring gamma-gamma and gamma-gamma-gamma coincidences of the prompt gamma-rays following the spontaneous fission of Cf-252. The data were taken with the Compton Suppression Spectrometer System at HHIRF. New high spin levels were observed in Ba-143,Ba-145,Ba-147. Only in Ba-143 are intertwined bands observed with the characteristics of the octupole structure found only in Ba-144. New high spin states observed in the N = 84 Te-136, Xe-138, Ba-140 nuclei exhibit a symmetry pattern suggestive of a pseudospin (f) over tilde-shell. For the first time in fission, the relative yields and neutron multiplicities were measured directly, Yields and multiplicities were measured directly for the Zr-Ce and Mo-Ba correlated fragment pairs by observing the coincidences between the gamma-rays in each fragment. Zero-neutron to ten-neutron emission yields were determined; the latter for the first time. The zero-neutron emission can be understood as a new example of cluster radioactivity. These results demonstrate that the use of the high resolution gamma-gamma-gamma coincidence technique employed here for the first time opens up a new approach to the study of the fission process that will provide previously inaccessible details of the process.