Signatures of higher-multipole deformations and non-coplanarity as essential, additional degrees-of-freedom in heavy-ion reactions

Abstract

Eloquent display of signatures of including higher-multipole (octupole and hexadecupole) deformations βλi, i=1,2,λ=2–4, and non-coplanar degrees-of-freedom Φ are shown here for the first time as essential, additional variables in low-energy heavy-ion reactions (HIR), within the dynamical cluster-decay model (DCM) of the collective clusterization process. In other words, a description in terms of quadrupole-deformed, “optimally” oriented coplanar nuclei is not sufficient, which therefore calls for both higher-multipole deformations (β3i and β4i; i=1,2) and non-coplanarity (Φ≠0∘) as the additional degrees-of-freedom. Such a convincing, real result appears in terms of the non-compound-nucleus (nCN) effect, the nCN cross section σnCN-content in σfusion, which is different for different compound nuclei (CN), i.e., CN specific, varying from an almost complete impure to pure CN decay while going successively from (β2i, θ2iopt, Φ=0∘) to (β2i-β4i, “compact” oriented θci, Φ≠0∘), which is further independent of the radioactive or nonradioactive nature of CN formed in different entrance channels, i.e., also independent of entrance channel target-projectile nuclei. This study plus our earlier study of spontaneous C14-cluster radioactivity provide a new set of variables, in terms of higher-multipole deformations and non-coplanarity degrees-of-freedom, to explore the real outcome of any low-energy HIR (plus spontaneous decay), which could in fact be already close to Nature.