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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Structure of 152Sm with (d,d') reactions in search of a tetrahedral symmetry signature

Chagnon-Lessard, Sophie 09 August 2012 (has links)
Nuclei near N=90 and Z=64 have recently been suggested to be `tetrahedral-magic'. One of the main signatures for tetrahedral symmetry is a vanishing quadrupole moment in low-lying negative-parity bands, resulting in very weak or even vanishing E2 matrix elements. With N=90 and Z=62, the transitional nucleus 152Sm is a potential candidate for relatively stable tetrahedral symmetry. Its structure was investigated using deuteron inelastic scattering with a 22 MeV polarized beam at the MP tandem Van de Graaff accelerator of the TU/LMU Munich. The scattered deuterons were momentum analyzed using the Q3D spectrometer. The experimental spectra obtained have allowed the extraction of high-quality differential cross-sections and analyzing powers for levels up to 1.8 MeV. The low-lying negative-parity bands are observed to be strongly populated and the angular distributions associated to their levels exhibit several structural features. The overall agreement is relatively good when considering strong intra-band E2 transitions, but further calculations must be performed to allow precise matrix element extraction. In particular, a simple population pathway test on the 1- state has demonstrated that calculations with vanishing E2 transitions in the negative-parity band are also capable of reproducing its experimental angular distributions. Therefore, the presence of tetrahedral symmetry signature in 152Sm is not excluded. / This work has been supported in part by the Natural Sciences and Engineering Research Council of Canada.

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