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.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OGU.10214/3842 |
| Date | 09 August 2012 |
| Creators | Chagnon-Lessard, Sophie |
| Contributors | Garrett, Paul E. |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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