Precision ground state mass of ${}^{12}\mathrm{Be}$ and an isobaric multiplet mass equation (IMME) extrapolation for $2^{+}$ and $0_2^{+}$ states in the $T=2$, $A=12$ multiplet

We report the mass measurement of the short-lived ${}^{12}\mathrm{Be}$ nuclide ($T_{1/2}=21.5$ ms) performed using the Penning trap mass spectrometer TITAN at TRIUMF. Our mass excess value of $25\hspace{0.5em}078.0(2.1)$ keV is in agreement with previous measurements, but is a factor of 7 more precise than the Atomic Mass Evaluation of 2003. To address an unresolved discussion on the spin assignment of isospin $T=2$ states in ${}^{12}\mathrm{C}$ and ${}^{12}\mathrm{O}$, we reevaluate the isobaric mass multiplet equation for the lowest lying $T=2$ multiplet in the $A=12$ system and use the extracted parameters to extrapolate from the known excited $2^{+}$ and $0^{+}$ states in ${}^{12}\mathrm{Be}$. Though this analysis favors the second known $T=2$ state in ${}^{12}\mathrm{C}$ to be $2^{+}$, $0^{+}$ cannot be excluded.

Figure 1

${}^{12}\mathrm{Be}$${}^{+}$ resonance with excitation time of $T_{\mathrm{rf}}=48$ ms with a fit of the theoretical line shape (solid line).

Figure 2

Previous results [34, 35, 36, 37, 38] for the mass excess (ME) of ${}^{12}\mathrm{Be}$ displayed together with this work. Measurements #1–4 are reaction based and #5 is a direct measurement by MISTRAL. The four most recent results are shown in the inset.

Figure 3

IMME extrapolation based on the IMME parameters of the lowest lying $T=2$ multiplet in $A=12$ and the known $T=2$ excited states in ${}^{12}\mathrm{Be}$.