Search for two-phonon octupole excitations in 146Gd

J. N. Orce; M. Kumar Raju; N. A. Khumalo; T. S. Dinoko; P. Jones; R. A. Bark; E. A. Lawrie; S. N. T. Majola; L. M. Robledo; B. Rubio; M. Wiedeking; J. Easton; E. A. Khaleel; B. V. Kheswa; N. Kheswa; M. S. Herbert; J. J. Lawrie; P. L. Masiteng; M. R. Nchodu; J. Ndayishimye; D. Negi; S. P. Noncolela; S. S. Ntshangase; P. Papka; D. G. Roux; O. Shirinda; P. S. Sithole; S. W. Yates

doi:10.1140/epja/i2016-16166-2

EPJ

Search for two-phonon octupole excitations in ¹⁴⁶Gd

J. N. Orce¹^*, M. Kumar Raju¹^,2, N. A. Khumalo¹^,2^,3, T. S. Dinoko¹^,2, P. Jones², R. A. Bark², E. A. Lawrie², S. N. T. Majola²^,4, L. M. Robledo⁵, B. Rubio⁶, M. Wiedeking², J. Easton¹^,2, E. A. Khaleel²^,7, B. V. Kheswa²^,7, N. Kheswa²^,1, M. S. Herbert¹, J. J. Lawrie², P. L. Masiteng¹^,2, M. R. Nchodu², J. Ndayishimye²^,7, D. Negi², S. P. Noncolela¹^,2, S. S. Ntshangase³, P. Papka²^,7, D. G. Roux⁸, O. Shirinda¹^,2, P. S. Sithole¹^,2 and S. W. Yates⁹

¹ Department of Physics, University of the Western Cape, P/B X17, 7535, Bellville, South Africa
² iThemba LABS, P.O. Box 722, 7129, Somerset West, South Africa
³ Department of Physics and Engineering, University of Zululand, 3886, KwaDlangezwa, South Africa
⁴ Department of Physics, University of Cape Town, Private Bag, 7701, Rondebosch, South Africa
⁵ Departamento de Física Teórica, Universidad Autónoma de Madrid, E-28049, Madrid, Spain
⁶ Instituto de Física Corpuscular, CSIC-Universidad de Valencia, E-46071, Valencia, Spain
⁷ Department of Physics, University of Stellenbosch, Private Bag X1, 7602, Matieland, South Africa
⁸ Department of Physics and Electronics, Rhodes University, 6410, Grahamstown, South Africa
⁹ Departments of Chemistry and Physics + Astronomy, University of Kentucky, 40506-0055, Lexington, KY, USA

Received: 20 March 2016
Revised: 24 May 2016
Accepted: 24 May 2016
Published online: 24 June 2016

Abstract

The low-spin structure of the nearly spherical nucleus ¹⁴⁶Gd was studied using the ¹⁴⁴Sm(⁴He, 2n) fusion-evaporation reaction. High-statistics $\gamma - \gamma$ coincidence measurements were performed at iThemba LABS with 7× 10⁹ $\gamma$ - $\gamma$ coincidence events recorded. Gated $\gamma$ -ray energy spectra show evidence for the $6^{+}_{2} \rightarrow 3^{-}_{1} \rightarrow 0^{+}_{1}$ cascade of E3 transitions in agreement with recent findings by Caballero and co-workers, but with a smaller branching ratio of $I_{\gamma} = 4.7(10)$ for the $6^{+}_{2} \rightarrow 3^{-}_{1}$ 1905.1 keV $\gamma$ ray. Although these findings may support octupole vibrations in spherical nuclei, sophisticated beyond mean-field calculations including angular-momentum projection are required to interpret in an appropriate way the available data due to the failure of the rotational model assumptions in this nucleus.

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Search for two-phonon octupole excitations in 146Gd

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Search for two-phonon octupole excitations in ¹⁴⁶Gd