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Neutron scattering from 28Si and 32S from 8.0 to 18.9 MeV, dispersive optical model analyses, and ground-state correlations

Publication ,  Journal Article
Al-Ohali, MA; Delaroche, JP; Howell, CR; Nagadi, MM; Naqvi, AA; Tornow, W; Walter, RL; Weisel, GJ
Published in: Physical Review C - Nuclear Physics
September 10, 2012

Background: The nucleon-nucleus dispersive optical model (DOM) has been successful in providing good fits to scattering data and in making valuable predictions for bound-state properties in single- and double-closed shell nuclei. However, the generalizability of the DOM remains an ongoing issue. Purpose: We investigate the DOM in the continuum and bound-state regions of the open-shell, self-conjugate nuclei 28Si and 32S. We collect new differential cross section and analyzing power data for elastic scattering at incident neutron energies between 8.0 and 18.9 MeV. Methods: The measurements were conducted using a pulsed deuteron beam, the 2He(d,n)3He source reaction, and time-of-flight techniques. All data were corrected for finite-geometry effects. Phenomenological DOM potentials were tailored to fit the differential and total cross section data, and then extrapolated to the bound-state regions. The DOM bound-state predictions were then compared to experimental data available for single-particle energies, occupation probabilities, root-mean-square radii, and spectroscopic factors. Results: The DOM bound-state predictions are in only fair agreement with experimental data and with USD shell-model predictions. Similar results are found after converting our neutron DOMs into proton DOMs. We investigate the separate effects of the dispersive surface and volume potential components on occupation probability and find that the volume component leads to a uniform depletion of the hole states, while the surface component acts mainly to deplete the valence orbitals. We compare these results to those of a variational multiparticle multihole configuration mixing (mp-mh CM) calculation using the Gogny D1S effective force. Conclusions: We find that the phenomenological DOM, which was originally designed for spherical nuclei, show certain deficiencies when applied to open-shell nuclei and suggest possible avenues of improvement. We also find that the predictions of occupation probability by the DOM using the dispersive surface component are similar to those by the mp-mh CM. This lends support to the interpretation that the surface absorption in the optical model originates from particle-vibration couplings, that is, long-range correlations. © 2012 American Physical Society.

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Published In

Physical Review C - Nuclear Physics

DOI

EISSN

1089-490X

ISSN

0556-2813

Publication Date

September 10, 2012

Volume

86

Issue

3

Related Subject Headings

  • Nuclear & Particles Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
 

Citation

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Al-Ohali, M. A., Delaroche, J. P., Howell, C. R., Nagadi, M. M., Naqvi, A. A., Tornow, W., … Weisel, G. J. (2012). Neutron scattering from 28Si and 32S from 8.0 to 18.9 MeV, dispersive optical model analyses, and ground-state correlations. Physical Review C - Nuclear Physics, 86(3). https://doi.org/10.1103/PhysRevC.86.034603
Al-Ohali, M. A., J. P. Delaroche, C. R. Howell, M. M. Nagadi, A. A. Naqvi, W. Tornow, R. L. Walter, and G. J. Weisel. “Neutron scattering from 28Si and 32S from 8.0 to 18.9 MeV, dispersive optical model analyses, and ground-state correlations.” Physical Review C - Nuclear Physics 86, no. 3 (September 10, 2012). https://doi.org/10.1103/PhysRevC.86.034603.
Al-Ohali MA, Delaroche JP, Howell CR, Nagadi MM, Naqvi AA, Tornow W, et al. Neutron scattering from 28Si and 32S from 8.0 to 18.9 MeV, dispersive optical model analyses, and ground-state correlations. Physical Review C - Nuclear Physics. 2012 Sep 10;86(3).
Al-Ohali, M. A., et al. “Neutron scattering from 28Si and 32S from 8.0 to 18.9 MeV, dispersive optical model analyses, and ground-state correlations.” Physical Review C - Nuclear Physics, vol. 86, no. 3, Sept. 2012. Scopus, doi:10.1103/PhysRevC.86.034603.
Al-Ohali MA, Delaroche JP, Howell CR, Nagadi MM, Naqvi AA, Tornow W, Walter RL, Weisel GJ. Neutron scattering from 28Si and 32S from 8.0 to 18.9 MeV, dispersive optical model analyses, and ground-state correlations. Physical Review C - Nuclear Physics. 2012 Sep 10;86(3).

Published In

Physical Review C - Nuclear Physics

DOI

EISSN

1089-490X

ISSN

0556-2813

Publication Date

September 10, 2012

Volume

86

Issue

3

Related Subject Headings

  • Nuclear & Particles Physics
  • 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics