skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Signature of shallow potentials in deep sub-barrier fusion reactions.

Abstract

No abstract prepared.

Authors:
; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); OUS
OSTI Identifier:
929220
Report Number(s):
ANL/PHY/JA-56397
Journal ID: ISSN 0556-2813; PRVCAN; TRN: US0804056
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. C; Journal Volume: 75; Journal Issue: Mar. 15, 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; THERMONUCLEAR REACTIONS; POTENTIALS; PATTERN RECOGNITION

Citation Formats

Misicu, S., Esbensen, H., and Physics. Signature of shallow potentials in deep sub-barrier fusion reactions.. United States: N. p., 2007. Web. doi:10.1103/PhysRevC.75.034606.
Misicu, S., Esbensen, H., & Physics. Signature of shallow potentials in deep sub-barrier fusion reactions.. United States. doi:10.1103/PhysRevC.75.034606.
Misicu, S., Esbensen, H., and Physics. Thu . "Signature of shallow potentials in deep sub-barrier fusion reactions.". United States. doi:10.1103/PhysRevC.75.034606.
@article{osti_929220,
title = {Signature of shallow potentials in deep sub-barrier fusion reactions.},
author = {Misicu, S. and Esbensen, H. and Physics},
abstractNote = {No abstract prepared.},
doi = {10.1103/PhysRevC.75.034606},
journal = {Phys. Rev. C},
number = Mar. 15, 2007,
volume = 75,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}
  • We extend a recent study that explained the steep falloff in the fusion cross section at energies far below the Coulomb barrier for the symmetric dinuclear system {sup 64}Ni+{sup 64}Ni to another symmetric system, {sup 58}Ni+{sup 58}Ni, and the asymmetric system {sup 64}Ni+{sup 100}Mo. In this scheme, the very sensitive dependence of the internal part of the nuclear potential on the nuclear equation of state determines a reduction of the classically allowed region for overlapping configurations and consequently a decrease in the fusion cross sections at bombarding energies far below the barrier. Within the coupled-channels method, including couplings to themore » low-lying 2{sup +} and 3{sup -} states in both target and projectile as well as mutual and two-phonon excitations of these states, we calculate and compare with the experimental data the fusion cross sections, S factors, and logarithmic derivatives for the above-mentioned systems and find good agreement with the data even at the lowest energies. We predict, in particular, a distinct double peaking in the S factor for the far sub-barrier fusion of {sup 58}Ni+{sup 58}Ni, which should be tested experimentally.« less
  • We propose a novel extension of the standard coupled-channels framework for heavy-ion reactions in order to analyze fusion reactions at deep-sub-barrier incident energies. This extension simulates a smooth transition between the two-body and the adiabatic one-body states. To this end, we damp gradually the off-diagonal part of the coupling potential, for which the position of the onset of the damping varies for each eigenchannel. We show that this model accounts well for the steep falloff of the fusion cross sections for the {sup 16}O+{sup 208}Pb, {sup 64}Ni+{sup 64}Ni, and {sup 58}Ni+{sup 58}Ni reactions.
  • Elastic scattering angular distributions were measured for the [sup 16]O+[sup 59]Co system, at energies close to the Coulomb barrier. Simultaneous analysis of elastic scattering and fusion cross sections were performed, based on the optical model. The part of the imaginary potential which accounts for the fusion was found to be of long range, with values of [ital r][sub [ital f]] larger than 1.42 fm, leading to the interpretation that fusion is decided at large separations, beyond the Coulomb barrier.
  • Fusion excitation functions have been measured for the first time with rather good accuracy for {sup 32}S+{sup 90}Zr and {sup 32}S+{sup 96}Zr near and below the Coulomb barrier. The sub-barrier cross sections for {sup 32}S+{sup 96}Zr are much larger than for {sup 32}S+{sup 90}Zr. A coupled-channels calculation considering the inelastic excitations is capable of describing sub-barrier enhancement only for {sup 32}S+{sup 90}Zr. The unexplained part for {sup 32}S+{sup 96}Zr is found to be correlated with the positive-Q-value intermediate neutron transfers in this system. The comparison with {sup 40}Ca+{sup 96}Zr suggests that couplings to the positive-Q-value neutron transfer channels may playmore » a role in the sub-barrier fusion enhancement. Multi-neutron transfers are taken into account in Zagrebaev's semiclassical model to explain the discrepancies of the sub-barrier fusion cross sections for {sup 32}S+{sup 96}Zr.« less
  • Near-barrier fusion excitation functions for the 12,14C, 16,18O + 208Pb reactions have been analyzed in the framework of the barrier-passing model using different forms of the nuclear potential and the phenomenology of a fluctuating barrier. The best-fit fusion potentials were used to estimate cluster decay probabilities from the corresponding ground states of Ra and Th, i.e., for the inverse decay process. The analysis supports the 'alpha-decay-like' scenario for carbon and oxygen emission from these nuclei.