English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Fission-fragment mass distributions are asymmetric in fission of typicalactinide nuclei for nucleon number $A$ in the range $228 \lnsim A \lnsim 258$and proton number $Z$ in the range $90\lnsim Z \lnsim 100$. For somewhatlighter systems it has been observed that fission mass distributions areusually symmetric. However, a recent experiment showed that fission of$^{180}$Hg following electron capture on $^{180}$Tl is asymmetric. We calculatepotential-energy surfaces for a typical actinide nucleus and for 12 evenisotopes in the range $^{178}$Hg--$^{200}$Hg, to investigate the similaritiesand differences of actinide compared to mercury potential surfaces and to whatextent fission-fragment properties, in particular shell structure, relate tothe structure of the static potential-energy surfaces. Potential-energysurfaces are calculated in the macroscopic-microscopic approach as functions offiveshape coordinates for more than five million shapes. The structure of thesurfaces are investigated by use of an immersion technique. We determineproperties of minima, saddle points, valleys, and ridges between valleys in the5D shape-coordinate space. Along the mercury isotope chain the barrier heightsand the ridge heights and persistence with elongation vary significantly andshow no obvious connection to possible fragment shell structure, in contrast tothe actinide region, where there is a deep asymmetric valley extending from thesaddle point to scission. The mechanism of asymmetric fission must be verydifferent in the lighter proton-rich mercury isotopes compared to the actinideregion and is apparently unrelated to fragment shell structure. Isotopeslighter than $^{192}$Hg have the saddle point blocked from a deep symmetricvalley by a significant ridge. The ridge vanishes for the heavier Hg isotopes,for which we would expect a qualitatively different asymmetry of the fragments.

The contrasting fission potential-energy structure of actinides and mercury isotopes