Experimental Evidence for Common Driving Effects in Low-Energy Fission from Sublead to Actinides

Isotopic distributions of fragments from fission of the neutron-deficient 178 Hg nuclide are reported. This experimental observable is obtained for the first time in the region around lead using an innovative approach based on inverse kinematics and the coincidence between the large acceptance magnetic spectrometer VAMOS + + and a new detection arm close to the target. The average fragment N/Z ratio and prompt neutron M-n multiplicity are derived and compared with current knowledge from actinide fission. A striking consistency emerges, revealing the unexpected dominant role of the proton subsystem with atomic number between the Z = 28 and 50 magic numbers. The origin of nuclear charge polarization in fission and fragment deformation at scission are discussed.

Automated summary

The isotopic distributions of fragments from the fission of neutron-deficient 178 Hg nuclide were studied, revealing a surprising dominance of the proton subsystem with atomic numbers between Z = 28 and 50. The study also compared the average fragment N/Z ratio and prompt neutron multiplicity with current knowledge from actinide fission, showing a striking consistency. Discussions on the origin of nuclear charge polarization in fission and fragment deformation at scission were also included.