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Title: Isotopic dependence of fusion barrier energies in reactions forming heavy elements

Abstract

The systematic dependence of fusion barrier energies on neutron excess can be determined over a broader range using radioactive nuclei. It is shown that precise measurements with a wide range of stable isotopes are necessary for optimum interpretation of radioactive beam measurements. New precision cross-section data for fusion of {sup 32,34,36}S projectiles with Pb isotopes are presented, aiding in a revised interpretation of recent {sup 38}S fusion data, which now appears more likely to follow the same trend as the stable isotopes than to show the unexpected behavior previously inferred.

Authors:
; ; ; ; ;  [1]
  1. Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200 (Australia)
Publication Date:
OSTI Identifier:
20995289
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 5; Other Information: DOI: 10.1103/PhysRevC.75.054603; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; CROSS SECTIONS; HEAVY ION FUSION REACTIONS; LEAD ISOTOPES; MASS NUMBER; NEUTRONS; SULFUR 32; SULFUR 34; SULFUR 36; SULFUR 38

Citation Formats

Hinde, D. J., Dasgupta, M., Herrald, N., Neilson, R. G., Newton, J. O., and Lane, M. A. Isotopic dependence of fusion barrier energies in reactions forming heavy elements. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.054603.
Hinde, D. J., Dasgupta, M., Herrald, N., Neilson, R. G., Newton, J. O., & Lane, M. A. Isotopic dependence of fusion barrier energies in reactions forming heavy elements. United States. doi:10.1103/PHYSREVC.75.054603.
Hinde, D. J., Dasgupta, M., Herrald, N., Neilson, R. G., Newton, J. O., and Lane, M. A. Tue . "Isotopic dependence of fusion barrier energies in reactions forming heavy elements". United States. doi:10.1103/PHYSREVC.75.054603.
@article{osti_20995289,
title = {Isotopic dependence of fusion barrier energies in reactions forming heavy elements},
author = {Hinde, D. J. and Dasgupta, M. and Herrald, N. and Neilson, R. G. and Newton, J. O. and Lane, M. A.},
abstractNote = {The systematic dependence of fusion barrier energies on neutron excess can be determined over a broader range using radioactive nuclei. It is shown that precise measurements with a wide range of stable isotopes are necessary for optimum interpretation of radioactive beam measurements. New precision cross-section data for fusion of {sup 32,34,36}S projectiles with Pb isotopes are presented, aiding in a revised interpretation of recent {sup 38}S fusion data, which now appears more likely to follow the same trend as the stable isotopes than to show the unexpected behavior previously inferred.},
doi = {10.1103/PHYSREVC.75.054603},
journal = {Physical Review. C, Nuclear Physics},
number = 5,
volume = 75,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • The role of higher order coupling of surface vibrations to the relative motion in heavy-ion fusion reactions at near-barrier energies is investigated. The coupled channels equations are solved to all orders and also in the linear and the quadratic coupling approximations. Taking {sup 64}Ni + {sup 92,96}Zr reactions as examples, it is shown that all order couplings lead to considerably improved agreement with the experimentally measured fusion cross sections and average angular momenta of the compound nucleus for such heavy, nearly symmetric systems. The importance of higher order coupling is also examined for asymmetric systems like {sup 16}O + {supmore » 112}Cd, {sup 144}Sm, for which previous calculations of the fusion cross section seemed to indicate that the linear coupling approximation was adequate. It is shown that the shape of the barrier distributions and the energy dependence of the average angular momentum can change significantly when the higher order couplings are included, even for systems where measured fusion cross sections may seem to be well reproduced by the linear coupling approximation. {copyright} {ital 1997} {ital The American Physical Society}« less
  • It is proposed that the transfer of two neutrons explains the relative enhancement in the sub-barrier fusion cross section of /sup 58/Ni + /sup 64/Ni with respect to /sup 58/Ni + /sup 58/Ni. Similar relative enhancements in other cases of low energy heavy-ion fusion reactions are noted.
  • 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.
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