Sensitive search for near-symmetric and super-asymmetric fusion-fission of the superheavy element Flerovium (Z=114)

Measurements of mass and angular distributions have been made for fission-like outcomes in reactions forming isotopes of flerovium (Z=114), using Ca-48, Ti-50, and Cr-54 projectiles. The dominant fast quasifission process, which masks the presence of fusion-fission, has minimum yield at the most backward angles, where the sensitivity to fusion-fission is thus highest. In fitting the backward angle mass spectra, only weak evidence for a component of super-asymmetric fission was found, but a near symmetric fission component was consistently required for the Ca-48 + Pu-244 reaction, giving upper limit to the fusion probabilities P-CN of similar to 10(-2), similar to 5 times lower than previous results. PCN for the Ti-50 reaction was lower than Ca-48, whilst no evidence of fusion-fission was found for the Cr-54 reaction. (C) 2021 The Authors. Published by Elsevier B.V.

Automated summary

Measurements were made on fission-like outcomes in reactions forming flerovium isotopes using different projectiles, revealing that the dominant fast quasifission process masks the presence of fusion-fission. Results show a weak evidence for a super-asymmetric fission component, with a consistently required near symmetric fission component for a specific reaction, indicating lower fusion probabilities compared to previous results.