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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

It is well known that most actinides fission into fragments of unequal size.The first attempt to understand this difference suggested that division leadingto one of the fragments being near doubly magic $^{132}$Sn is favored by gainin binding energy. After the Strutinsky shell-correction method was developedan alternative idea that gained popularity was that the fission saddle might belower for mass-asymmetric shapes and that this asymmetry was preserved untilscission. Recently it was observed [Phys. Rev. Lett. {\bf 105} (2010) 252502]that $^{180}$Hg preferentially fissions asymmetrically in contradiction to thefragment-magic-shell expectation which suggested symmetric division peakedaround $^{90}$Zr, with its magic neutron number $N=50$, so it was presented asa "new type of asymmetric fission". However, in a paper [Phys. Lett. 34B (1971)349] a "simple" microscopic mechanism behind the asymmetry of the actinidefission saddle points was proposed to be related the coupling between levels oftype [40$\Lambda\Omega$] and [51$\Lambda\Omega$]. The paper then generalizesthis idea and made the remarkable prediction that analogous features couldexist in other regions. In particular it was proposed that in the rare-earthregion couplings between levels of type [30$\Lambda\Omega$] and[41$\Lambda\Omega$] would favor mass-asymmetric outer saddle shapes. In thispicture the asymmetry of $^{180}$Hg is not a "new type of asymmetric fission"but of analogous origin as the asymmetry of actinide fission. This predictionhas never been cited in the discussion of the recently observed fissionasymmetries in the "new region of asymmetry", in nuclear physics also referredto as the rare-earth region. We show by detailed analysis that the mechanism ofthe saddle asymmetry in the sub-Pb region is indeed the one predicted half acentury ago.

The microscopic mechanism behind the fission-barrier asymmetry (II): The rare-earth region $50 < Z < 82$ and $82 < N < 126$