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arXiv · 1204.4133

Elucidation of the anomalous A = 9 isospin quartet behaviour

M. Brodeur·T. Brunner·S. Ettenauer·A. Lapierre·R. Ringle·B. A. Brown·D. Lunney·J. Dilling
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Abstract

Recent high-precision mass measurements of $^{9}$Li and $^{9}$Be, performed with the TITAN Penning trap at the TRIUMF ISAC facility, are analyzed in light of state-of-the-art shell model calculations. We find an explanation for the anomalous Isobaric Mass Multiplet Equation (IMME) behaviour for the two $A$ = 9 quartets. The presence of a cubic $d$ = 6.3(17) keV term for the $J^{\pi}$ = 3/2$^{-}$ quartet and the vanishing cubic term for the excited $J^{\pi}$ = 1/2$^{-}$ multiplet depend upon the presence of a nearby $T$ = 1/2 state in $^{9}$B and $^{9}$Be that induces isospin mixing. This is contrary to previous hypotheses involving purely Coulomb and charge-dependent effects. $T$ = 1/2 states have been observed near the calculated energy, above the $T$ = 3/2 state. However an experimental confirmation of their $J^{\pi}$ is needed.

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M. Brodeur, T. Brunner, S. Ettenauer, A. Lapierre, R. Ringle, B. A. Brown, D. Lunney, J. Dilling. 2012-04-18. Elucidation of the anomalous A = 9 isospin quartet behaviour. https://doi.org/10.1103/physrevlett.108.212501

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