Multi-modal mass-asymmetric fission of Pt from simultaneous mass-kinetic energy fitting
B.M.A. Swinton-Bland (Department of Nuclear Physics and Accelerator Applications, Research School of Physics, Australian National University, Canberra, Australia)
; J. Buete (Department of Nuclear Physics and Accelerator Applications, Research School of Physics, Australian National University, Canberra, Australia); D.J. Hinde (Department of Nuclear Physics and Accelerator Applications, Research School of Physics, Australian National University, Canberra, Australia); M. Dasgupta (Department of Nuclear Physics and Accelerator Applications, Research School of Physics, Australian National University, Canberra, Australia); T. Tanaka (Department of Nuclear Physics and Accelerator Applications, Research School of Physics, Australian National University, Canberra, Australia); et al - Show all 15 authors
The observation of mass-asymmetric fission in neutron-deficient $^{180}$Hg dramatically expanded the region of mass-asymmetric fission found across the nuclide chart, and has led to intense experimental and theoretical investigations into the fission of sub-lead nuclei. In particular, two major questions have been raised: how many fission modes are present in the fission of sub-lead nuclides, and which shells dictate these modes?Notably, investigations of the fission modes of $^{178}$Pt have led to contrasting results. To solve this disparity, new high-statistics data have been measured at the lowest excitation energy to-date using the CUBE fission spectrometer at The Australian National University. A new fitting procedure was developed to fit the high-statistics two-dimensional mass-kinetic energy distribution without external constraints.The fission of $^{178}$Pt can best be described by three fission modes: one mass-symmetric and two mass-asymmetric. Comparisons to previous analyses highlight the necessity of fitting the two-dimensional mass-kinetic energy distribution, rather than fitting slices of individual one-dimensional projections of the full distribution. Systematic studies of high-statistics measurements, combined with a rigorous statistical analysis offer the best chance to determine the shell effects responsible for multi-modal mass-asymmetric fission in this region of the nuclide chart.
