The structure of ${}^{34}\mathrm{Si}$ was studied through $\gamma$ spectroscopy separately in the ${\beta }^{-}$ decays of ${}^{34}\mathrm{Mg}$ and ${}^{34}\mathrm{Al}$ at the ISOLDE facility of CERN. Different configurations in ${}^{34}\mathrm{Si}$ were populated independently from the two recently identified $\beta$-decaying states in ${}^{34}\mathrm{Al}$ having spin-parity assignments $J^{\pi }=4^{-}$ dominated by the normal configuration $\pi {\left(d_{5/2}\right)}^{-1}\otimes \nu \left(f_{7/2}\right)$ and $J^{\pi }=1^{+}$ by the intruder configuration $\pi {\left(d_{5/2}\right)}^{-1}\otimes \nu {\left(d_{3/2}\right)}^{-1}{\left(f_{7/2}\right)}^2$. The paper reports on spectroscopic properties of ${}^{34}\mathrm{Si}$ such as an extended level scheme, spin and parity assignments based on $log\left(ft\right)$ values and $\gamma$-ray branching ratios, absolute $\beta$ feeding intensities, and neutron emission probabilities. A total of 11 newly identified levels and 26 transitions were added to the previously known level scheme of ${}^{34}\mathrm{Si}$. Large scale shell-model calculations using the SDPF-U-MIX interaction, able to treat higher order intruder configurations, are compared with the new results and conclusions are drawn concerning the predictive power of SDPF-U-MIX, the $N=20$ shell gap, the level of mixing between normal and intruder configurations for the $0_1^{+}$, $0_2^{+}$, and $2_1^{+}$ states, and the absence of triaxial deformation in ${}^{34}\mathrm{Si}$.

• Received 26 February 2019
• Revised 29 March 2019

DOI:https://doi.org/10.1103/PhysRevC.100.034306

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Published by the American Physical Society