Properties of low-lying levels of ${}^{14}\mathrm{Be}$

In a simple model, I have calculated energy splittings and wave functions of low-lying states in ${}^{14}\mathrm{Be}$. Data from $2n$ decays of $2^{+}$ states allow estimates of the ($sd$)${}^4$ admixtures in the predominantly ($sd$)${}^2$ states. I demonstrate that the first $2^{+}$ state is predominantly of $ds$ structure, not $dd$ as recently claimed.

Figure 1

For 2n decay of the first 2${}^{+}$ state of ${}^{14}$Be, the calculated dd/ds ratio is plotted vs $A^2$, the amount of (sd)${}^2$ in the decaying state. The horizontal lines represent the experimental result [7]. Calculation and experiment agree for $A^2$ = 0.84(4).

Figure 2

Same as Fig. 1, but for the second 2${}^{+}$ state of ${}^{14}$Be. The calculated dd/ds ratio is plotted (solid curve) vs $A^{\prime 2}$, the amount of (sd)${}^2$ in the decaying state. The dashed horizontal lines represent the experimental ratio, implying $A^{\prime 2}$ ∼ 0.72.