Browsing by Author "Marin-Lambarri, D. J."

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    Second T = 3/2 state in 9B and the isobaric multiplet mass equation
    (American Physical Society, 2018) Mukwevho, N. J.; Rebeiro, B. M.; Marin-Lambarri, D. J.; Triambak, S.; Adsley, P.; Kheswa, N. Y.; Neveling, R.; Pellegri, L.; Pesudo, V.; Smit, F. D.; Akakpo, E. H.; Brümmer, J. W.; Jongile, S.; Kamil, M.; Mabika, P. Z.; Nemulodi, F.; Orce, J. N.; Papka, P.; Steyn, G. F.; Yahia-Cherif, W.
    Recent high-precision mass measurements and shell-model calculations [M. Brodeur et al., Phys. Rev. Lett. 108, 212501 (2012)] have challenged a longstanding explanation for the requirement of a cubic isobaric multiplet mass equation for the lowest A=9 isospin quartet. The conclusions relied upon the choice of the excitation energy for the second T=3/2 state in 9B, which had two conflicting measurements prior to this work. We remeasured the energy of the state using the 9Be(3He,t) reaction and significantly disagree with the most recent measurement. Our result supports the contention that continuum coupling in the most proton-rich member of the quartet is not the predominant reason for the large cubic term required for A=9 nuclei.
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    α clustering in ²⁸Si probed through the identification of high-lying 0⁺ states
    (American Physical Society, 2017) Adsley, P.; Jenkins, D. G.; Cseh, J.; Dimitriova, S. S.; Brummer, J. W.; Li, K. C. W.; Marin-Lambarri, D. J.; Lukyanov, K.; Kheswa, N. Y.; Neveling, R.; Papka, P.; Pellegri, L.; Pesudo, V.; Pool, L. C.; Riczu, G.; Smit, F. D.; Van Zyl, J. J.; Zemlyanaya, E.
    Background: Aspects of the nuclear structure of light α-conjugate nuclei have long been associated with nuclear clustering based on α particles and heavier α-conjugate systems such as ¹²C and ¹⁶O. Such structures are associated with strong deformation corresponding to superdeformed or even hyperdeformed bands. Superdeformed bands have been identified in ⁴⁰Ca and neighboring nuclei and find good description within shell model, mean-field, and α-cluster models. The utility of the α-cluster description may be probed further by extending such studies to more challenging cases comprising lighter α-conjugate nuclei such as ²⁴Mg, ²⁸Si, and ³²S. Purpose: The purpose of this study is to look for the number and energy of isoscalar 0⁺ states in ²⁸Si. These states are the potential bandheads for superdeformed bands in ²⁸Si corresponding to the exotic structures of ²⁸Si. Of particular interest is locating the 0⁺ bandhead of the previously identified superdeformed band in ²⁸Si. Methods: α-particle inelastic scattering from a natSi target at very forward angles including 0∘ has been performed at the iThemba Laboratory for Accelerator-Based Sciences in South Africa. Scattered particles corresponding to the excitation energy region of 6 to 14 MeV were momentum-analysed in the K600 magnetic spectrometer and detected at the focal plane using two multiwire drift chambers and two plastic scintillators. Results: Several 0⁺ states have been identified above 9 MeV in ²⁸Si. A newly identified 9.71 MeV 0⁺ state is a strong candidate for the bandhead of the previously discussed superdeformed band. The multichannel dynamical symmetry of the semimicroscopic algebraic model predicts the spectrum of the excited 0⁺ states. The theoretical prediction is in good agreement with the experimental finding, supporting the assignment of the 9.71-MeV state as the bandhead of a superdeformed band. Conclusion: Excited isoscalar 0⁺ states in ²⁸Si have been identified. The number of states observed in the present experiment shows good agreement with the prediction of the multichannel dynamical symmetry.