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Title: Recent developments in quasi-elastic scattering around the Coulomb barrier

Abstract

We discuss two recent topics on heavy-ion quasi-elastic scattering at energies around the Coulomb barrier. The first topic is an application of quasi-elastic scattering at deep-subbarrier energies to extracting the surface diffuseness parameter of the nucleus-nucleus potential. The second topic is a coupled-channels analysis for the quasi-elastic barrier distribution for the 70Zn + 208Pb reaction. We show that the coupled-channels calculations which include the multi-phonon excitations in the colliding nuclei reproduce reasonably well the experimental excitation function for quasi-elastic scattering at backward angles and the barrier distribution for this reaction.

Authors:
 [1]
  1. Department of Physics, Tohoku University, Sendai 980-8578 (Japan)
Publication Date:
OSTI Identifier:
21056784
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 891; Journal Issue: 1; Conference: 6. Symposium on nuclear physics, Tours (France), 5-8 Sep 2006; Other Information: DOI: 10.1063/1.2713503; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; COULOMB FIELD; COUPLED CHANNEL THEORY; DISTRIBUTION; EXCITATION; EXCITATION FUNCTIONS; HEAVY ION FUSION REACTIONS; LEAD 208 TARGET; NUCLEON-NUCLEON POTENTIAL; PHONONS; QUASI-ELASTIC SCATTERING; ZINC 70 REACTIONS

Citation Formats

Hagino, K. Recent developments in quasi-elastic scattering around the Coulomb barrier. United States: N. p., 2007. Web. doi:10.1063/1.2713503.
Hagino, K. Recent developments in quasi-elastic scattering around the Coulomb barrier. United States. doi:10.1063/1.2713503.
Hagino, K. Mon . "Recent developments in quasi-elastic scattering around the Coulomb barrier". United States. doi:10.1063/1.2713503.
@article{osti_21056784,
title = {Recent developments in quasi-elastic scattering around the Coulomb barrier},
author = {Hagino, K.},
abstractNote = {We discuss two recent topics on heavy-ion quasi-elastic scattering at energies around the Coulomb barrier. The first topic is an application of quasi-elastic scattering at deep-subbarrier energies to extracting the surface diffuseness parameter of the nucleus-nucleus potential. The second topic is a coupled-channels analysis for the quasi-elastic barrier distribution for the 70Zn + 208Pb reaction. We show that the coupled-channels calculations which include the multi-phonon excitations in the colliding nuclei reproduce reasonably well the experimental excitation function for quasi-elastic scattering at backward angles and the barrier distribution for this reaction.},
doi = {10.1063/1.2713503},
journal = {AIP Conference Proceedings},
number = 1,
volume = 891,
place = {United States},
year = {Mon Feb 26 00:00:00 EST 2007},
month = {Mon Feb 26 00:00:00 EST 2007}
}
  • We summarize recent theoretical activities on heavy-ion quasi-elastic scattering at energies around the Coulomb barrier. We first introduce a barrier distribution defined in terms of cross sections of large-angle quasi-elastic scattering. We discuss possible advantages for its exploitation, putting a particular emphasis on future experiments with radioactive beams. We then present our recent systematic studies on quasi-elastic scattering at deep-subbarrier energies, that offer an unambiguous way to extract the surface diffuseness parameter of the nucleus-nucleus potential.
  • We invert experimental data for heavy-ion fusion cross sections at energies well below the Coulomb barrier in order to directly determine the internucleus potential between the colliding nuclei. In contrast to the previous applications of the inversion formula, we explicitly take into account the effect of channel couplings on fusion reactions, by assuming that fusion cross sections at deep subbarrier energies are governed by the lowest barrier in the barrier distribution. The surface region of the internuclear potential is determined from quasi-elastic scattering at deep subbarrier energies, while the inner part is determined with the WKB formula. We apply thismore » procedure to the {sup 16}O+{sup 144}Sm and {sup 16}O+{sup 208}Pb reactions, and find that the inverted internucleus potential are much thicker than phenomenological potentials.« less
  • The investigation of nuclear reactions near the Coulomb barrier poses a number of problematic issues which have remained unsolved for a long time: The out-of-phase problem between theoretical predictions and experimental data, the reproduction of the oscillatory structure near the Coulomb barrier, and the consistent description of angular distributions together with the excitation functions data are just some of these issues. To address and overcome them, we examine the elastic scattering of the {sup 12}C + {sup 24}Mg system within the framework of the optical model with two small potentials in addition to the nuclear potential. The experimental data havemore » been analyzed in the laboratory system from 16.0 to 24.0 MeV and excellent agreement between theoretical results and the measured experimental data has been obtained by using this modified optical potential. We show that the presence of the two small additional potentials creates a deepening in the surface region of the nuclear potential, which is very effective for the interference of the internal and barrier waves. This work is important in showing the sensitivity of the cross section to the fine details of the optical potential. It is also argued that the two small additional potentials take into account the coupling effect like that of the coupled channels and as a result reduce the strength of the imaginary potential. In this context, the results of the optical model are compared with that of the coupled channels.« less
  • Collisions induced by {sup 9,10,11}Be on a {sup 64}Zn target at the same c.m. energy were studied. For the first time, strong effects of the {sup 11}Be halo structure on elastic-scattering and reaction mechanisms at energies near the Coulomb barrier are evidenced experimentally. The elastic-scattering cross section of the {sup 11}Be halo nucleus shows unusual behavior in the Coulomb-nuclear interference peak angular region. The extracted total-reaction cross section for the {sup 11}Be collision is more than double the ones measured in the collisions induced by {sup 9,10}Be. It is shown that such a strong enhancement of the total-reaction cross sectionmore » with {sup 11}Be is due to transfer and breakup processes.« less
  • The total reaction cross section {sigma}{sub reac} is a valuable measure for the prediction of {alpha}-induced reaction cross sections within the statistical model and for the comparison of scattering of tightly bound projectiles to weakly bound and exotic projectiles. Here we provide the total reaction cross sections {sigma}{sub reac} derived from our previously published angular distributions of elastic {alpha}-nucleus scattering on {sup 89}Y, {sup 92}Mo, {sup 112,124}Sn, and {sup 144}Sm at energies around the Coulomb barrier.