7-11 July 2014
Africa/Johannesburg timezone
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Octupole correlations and Collective Couplings in the rare earth nucleus 154Dy

Presented by Mr. George ZIMBA on 8 Jul 2014 from 11:30 to 11:50
Type: Oral Presentation
Session: NPRP
Track: Track B - Nuclear, Particle and Radiation Physics

Abstract

There is currently less information available on the structure of <sup>154</sup>Dy at low spins. The question still remains whether at low spins the structure exhibits permanent octupole deformation [1] or aligned tidal wave octupole phonons [2]. Intermediate spins of the nucleus <sup>154</sup>Dy were populated via the <sup>155</sup>Gd (3He, 4n) <sup>154</sup>Dy reaction at 45 MeV at iThemba LABS using AFRODITE array spectrometer. The even-even nucleus <sup>154</sup>Dy with 6 neutrons and 2 protons outside the closed shell is nearly spherical. The N = 88 isotones have remarkable features; They are at a peak in the |M(E3)| <sup>2</sup> transition strength of 0<sup>+</sup><sub>1</sub> → 3<sup>-</sup><sub>1</sub> transitions for even-even nuclei as a function of neutron number usually called octupole vibration [34]. This was first stated by Chasman theoretically [1] whereby the first excited states in some nuclei have an octupole deformed first excited state with a quadruple deformation in the ground state and shown experimentally for <sup>154</sup>Gd<sub>88</sub> [4]. The strong E3 properties have been described and explained as due to the nearness of &Delta J<sup> &pi</sup>=3<sup> -</sup> shell model orbits to the Fermi surface. They also have very strong E0 transitions from the band built on the 0 <sup>+</sup><sub>2</sub> states to the ground state bands [3, 5]. The measurements we have made on <sup>154</sup>Dy are motivated by the findings from our studies of the isotones <sup>152</sup>Gd and <sup>150</sup>Sm from [6] where we observed octupole correlations between the 0 <sup>+</sup><sub>2</sub> states and the lowest-lying negative parity band, commonly known as the octupole band. References [1] R. R. Chasman, Phys. Rev. Lett. 42, 630 (1979). [2] S. Frauendorf, Phys. Rev. C77, 021304(R) (2008). [3] S. P. Bvumbi et al., Phys. Rev. C 87, 044333 (2013). [4] S P Bvumbi, “Spin and Parity Assignment in 152Gd Investigating Octupole Structures”; MSc thesis, University of Western Cape (2008). [5] S. Frauendorf, Y. Gu, J. Sun, Tidal waves as yrast states in transitional nuclei (2007). [6] S. P. Bvumbi, “Investigation of octupole correlations and collective couplings in the rare earth nucleus 150Sm” PhD thesis, University of Johannesburg, (2013).

Award

yes

Level

MSc

Supervisor

SUZAN PHUMUDZO BVUMBI University of Johannesburg suzan@tlabs.ac.za

Paper

Yes

Place

Room: D Les 101


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