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Title: Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al

Abstract

Elastic scattering of the weakly bound {sup 6}Li on {sup 27}Al was measured at near-barrier energies. The data analysis was performed using a Woods-Saxon shape optical potential and also using the double-folding Sao Paulo potential. The results show the presence of the breakup threshold anomaly (BTA), an anomalous behavior when compared with the scattering of tightly bound nuclei. This behavior is attributed to a repulsive polarization potential produced by the coupling to the continuum breakup states.

Authors:
 [1];  [2]; ; ; ; ; ; ; ; ;  [1]; ; ; ; ;  [3]
  1. Laboratorio TANDAR, Comision Nacional de Energia Atomica, Av. General Paz 1499, 1650 San Martin, Buenos Aires (Argentina)
  2. (Argentina)
  3. Instituto de Fisica, Universidade Federal Fluminense, Av. Litoranea s/n, Gragoata, Niteroi, R.J., 24210-340 (Brazil)
Publication Date:
OSTI Identifier:
20990988
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 1; Other Information: DOI: 10.1103/PhysRevC.75.017602; (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; ALUMINIUM 27; COUPLING; DATA ANALYSIS; ELASTIC SCATTERING; LITHIUM 6; POLARIZATION; SHAPE; WOODS-SAXON POTENTIAL

Citation Formats

Figueira, J. M., Departamento de Fisica, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, 1428 Buenos Aires, Niello, J. O. Fernandez, Abriola, D., Arazi, A., Capurro, O. A., Barbara, E. de, Marti, G. V., Heimann, D. Martinez, Negri, A. E., Pacheco, A. J., Padron, I., Gomes, P. R. S., Lubian, J., Correa, T., and Paes, B. Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.017602.
Figueira, J. M., Departamento de Fisica, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, 1428 Buenos Aires, Niello, J. O. Fernandez, Abriola, D., Arazi, A., Capurro, O. A., Barbara, E. de, Marti, G. V., Heimann, D. Martinez, Negri, A. E., Pacheco, A. J., Padron, I., Gomes, P. R. S., Lubian, J., Correa, T., & Paes, B. Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al. United States. doi:10.1103/PHYSREVC.75.017602.
Figueira, J. M., Departamento de Fisica, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, 1428 Buenos Aires, Niello, J. O. Fernandez, Abriola, D., Arazi, A., Capurro, O. A., Barbara, E. de, Marti, G. V., Heimann, D. Martinez, Negri, A. E., Pacheco, A. J., Padron, I., Gomes, P. R. S., Lubian, J., Correa, T., and Paes, B. Mon . "Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al". United States. doi:10.1103/PHYSREVC.75.017602.
@article{osti_20990988,
title = {Breakup threshold anomaly in the elastic scattering of {sup 6}Li on {sup 27}Al},
author = {Figueira, J. M. and Departamento de Fisica, FCEyN, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon 1, 1428 Buenos Aires and Niello, J. O. Fernandez and Abriola, D. and Arazi, A. and Capurro, O. A. and Barbara, E. de and Marti, G. V. and Heimann, D. Martinez and Negri, A. E. and Pacheco, A. J. and Padron, I. and Gomes, P. R. S. and Lubian, J. and Correa, T. and Paes, B.},
abstractNote = {Elastic scattering of the weakly bound {sup 6}Li on {sup 27}Al was measured at near-barrier energies. The data analysis was performed using a Woods-Saxon shape optical potential and also using the double-folding Sao Paulo potential. The results show the presence of the breakup threshold anomaly (BTA), an anomalous behavior when compared with the scattering of tightly bound nuclei. This behavior is attributed to a repulsive polarization potential produced by the coupling to the continuum breakup states.},
doi = {10.1103/PHYSREVC.75.017602},
journal = {Physical Review. C, Nuclear Physics},
number = 1,
volume = 75,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2007},
month = {Mon Jan 15 00:00:00 EST 2007}
}
  • Measurements of elastic scattering for the {sup 6}Li+{sup 90}Zr system has been performed at various energies, namely, 11, 12, 13, 15, 17, 19, 21, 25, and 30 MeV, to study the energy dependence of the interaction potential. Angular distributions have been measured in a wide angular range to extract the behavior of the potential reliably. The data have been analyzed using the phenomenological Woods-Saxon shaped optical potential and the double folding potential. The potential behavior shows the characteristics of the breakup threshold anomaly, namely, the increase in the imaginary potential near the barrier with a small reduction in the realmore » part. Continuum-discretized-coupled-channel (CDCC) calculations give a good description of the measured elastic scattering data and predict large breakup coupling effects. The polarization potentials extracted from the CDCC calculations have been studied for the present system along with those for the {sup 6}Li+{sup 208}Pb, and {sup 6}Li+{sup 28}Si systems, and a similar energy dependence has been obtained for all the cases considered.« less
  • We have measured the elastic scattering of the weakly bound {sup 6}Li on the {sup 116,112}Sn targets, at energies close to the Coulomb barrier. The energy dependence of the interaction potential has been investigated by two different methods and the presence of the breakup threshold anomaly is observed. We have also derived the total reaction cross sections for the above systems and compared them to those of other systems with halo, weakly bound, and tightly bound projectiles on targets with similar masses. The reaction cross sections are largest for systems with halo nuclei, then the systems with no-halo weakly boundmore » nuclei, and the smallest cross sections are those for tightly bound systems.« less
  • To study the conditions leading to the appearance of the threshold anomaly in systems involving weakly bound projectiles we measured elastic scattering cross sections for the {sup 7}Li+{sup 27}Al system at ten different bombarding energies. The results were exhaustively analyzed using different optical model potentials. The similar behavior observed in all these analyses allows us to conclude that no threshold anomaly is found for the present system.
  • Elastic scattering of the weakly bound {sup 9}Be on {sup 27}Al was measured at near barrier energies. The optical model data analysis with the real and imaginary parts of a global double-folding potential does not show strong evidence of the usual threshold anomaly. The same result was obtained by using a Woods-Saxon shape optical potential and calculating the potential strengths at the strong absorption radius. The reason for this behavior may be explained by the presence of break-up and/or transfer channels at low energies.