In the past, the mirror asymmetry parameter has been proposed as a probing mechanism for the presence of beyond the standard model second-class currents in nuclear beta decay transitions. However, this was hindered by large uncertainties in the required nuclear structure correction terms. Recently, a new calculation of these corrections attempted to, but could not fully, explain the negative mirror asymmetry between the ${}^{28}\mathrm{Al}\left({\beta }^{-}\right){}^{28m}\mathrm{Si}$ and ${}^{28}\mathrm{P}\left({\beta }^{+}\right){}^{28m}\mathrm{Si}$ decays. To put the mirror asymmetry parameter on a more solid footing, the half-life of ${}^{28}\mathrm{Al}$ was measured for the first time using a radioactive ion beam at the Nuclear Science Laboratory of the University of Notre Dame. The new result, $t_{1/2}=134.432\left(34\right)$ s, is consistent with most of the past data except for one highly discrepant measurement. The new mirror asymmetry parameter of –3.5(10)$\%$ still does not agree with nuclear structure calculations.

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• Beta decay
• Electroweak interaction
• Lifetimes & widths
• 20 ≤ A ≤ 38