Potential pockets in the238U+238U system and their possible consequences

Abstract

Within the double-folding model the separation, shape, and orientation dependence of the interaction potential is studied for two heavy ions. An effective nucleon-nucleon interaction (M3Y) derived from G-matrix elements and based upon the Reid soft-core potential is used. Deformed Fermi-type matter densities with static quadrupole and hexadecapole deformations were utilized. The model is applied to the 238U+238U system and shows dramatic dependence on the deformations and orientations.

64Ni+64Nifusion reaction calculated with the density-constrained time-dependent Hartree-Fock formalism

“…Fortunately, test calculations using the double-folding method described in Ref. [18] reveal that the dependence on the Euler angle ∆α is negligible in our case so we put ∆α = 0. In Fig.…”

Heavy-ion interaction potential deduced from density-constrained time-dependent Hartree-Fock calculation

“…While asymptotically such potentials are determined from Coulomb and centrifugal interactions, the short distance behavior strongly depends on the nuclear surface properties and the readjustments of the combined nuclear system, resulting in potential pockets, which determine the characteristics of the compound nuclear system.Among the various approaches for calculating ion-ion potentials are: 1) Phenomenological models such as the Bass model [1,2], the proximity potential [3,4,5,6], and potentials obtained via the double-folding method [7,8,9,10]. Some of these potentials have been fitted to experimental fusion barrier heights and have been remarkably successful in describing scattering data.…”

“…1 are two widely used phenomenological potentials, the standard proximity potential for two spherical nuclei [3,4,5] and the double-folding potential with M3Y effective NN interaction [7,8,9,10]. We evaluate the double-folding integral for the strong nuclear and Coulomb interaction in momentum space [10]. For the charge and matter densities we utilized generalized Fermi distributions whose parameters were determined from electron scattering experiments [25].…”

Systematics of spontaneous positron lines

“…These were proposed to originate from spontaneous positron production [-4, 5] due to the decay of the neutral vacuum to the charged vacuum [-18-20], assuming that a small fraction of the collisions leads to a nuclear reaction with very long delay time. This picture was supported by theoretical evidence [21,22] that in col-lisions of strongly deformed nuclei, like U+U, a pocket in the nuclear scattering potential may exist. When hitting quasibound states in the pocket during a collision close to the Coulomb barrier, a quasimolecular nuclear composite system might be formed, thereby increasing the delay time 1-23-26].…”

“…Such a scenario can be imagined in a nearly central heavy ion collision at a bombarding energy close to the Coulomb barrier where the two nuclei touch each other at almost vanishing kinetic energy. Calculations of heavy ion interaction potentials including the static deformations of the two nuclei [21,22] indicate the existence of a pocket in the scattering potential supporting the formation of a combined molecular-type "giant nucleus". Since the projectile has come almost to a stop, there will be little kinetic energy left for nuclear excitations thus providing for a cold reaction process.…”