Figure 1

Experimental level scheme of ${}^8\mathrm{B}$ and ${}^8\mathrm{Li}$ at excitation energies below 4 MeV. New states are shown in red (2.55 and 1.9). The dashed-dotted line indicates that the state is tentative.Reuse & Permissions

Figure 2

Scatter plot of kinematic coincidence between detected protons and ${}^7\mathrm{Be}$ ions. Regions that correspond to elastic and inelastic scatterings are labeled. The schematic of the experimental setup with a sandwich of three annular silicon strip detectors (S2 design by Micron Semiconductor ltd.) for the light recoils and a single S2 detector for the heavy recoils is shown in the inset.Reuse & Permissions

Figure 3

Excitation functions of ${}^7\mathrm{Be}+p$ elastic (top) and inelastic (bottom) scatterings. Data from three different runs are shown. The open and solid circles correspond to the run at 18.5 MeV of ${}^7\mathrm{Be}$ with $1.5\text{−}\mathrm{mg}/{\mathrm{cm}}^2$ and $2\text{−}\mathrm{mg}/{\mathrm{cm}}^2$ targets, respectively, and the stars are at 22 MeV with a $2.5\text{−}\mathrm{mg}/{\mathrm{cm}}^2$ target. The black solid curve is an $R$-matrix fit with only the known $3^{+}$ and $2^{-}$ states at 2.3 and 3.5 MeV, respectively. The red short-dashed line includes the contribution of the higher-lying $1^{+}$ states assumed at 3.0 MeV. The blue dashed-dotted line shows the $1^{+}$ state shifted to 2.5 MeV, and the green long-dashed line also includes the $1^{-}$ state introduced at 5 MeV. The black dashed-double-dotted curve in the bottom panel shows the excitation function of the ${}^7\mathrm{Be}(p,p^{\prime }){}^7\mathrm{Be}(0.43)$ reaction from the direct mechanism.Reuse & Permissions

Figure 4

Final $R$-matrix fit of the experimental data, with the new $2^{+}$ and $0^{+}$ states. ${}^7\mathrm{Be}+p$ elastic scattering data at three c.m. angles are shown in the top panels (a)–(c), and inelastic data are shown in the bottom panels (d)–(f). The solid blue line is the best fit, the dashed red line is a fit with $1^{+}$ at 1.9 MeV instead of $0^{+}$, and the green dashed-dotted line is a fit without the $0^{+}$. The dashed-double-dotted cyan line in the bottom panel is TDCSM calculations with the known states in ${}^8\mathrm{B}$ and the new $0^{+}$ and $2^{+}$ at 1.9 and 2.55 MeV, respectively.Reuse & Permissions

Figure 5

Comparison of the experimental data to the predictions of the ab initio models. The subset Exp shows experimental data. The new states in ${}^8\mathrm{B}$ observed in this experiment are shown in red [$0^{+}$ (below $3^{+}$) and $2^{+}$ (above $3^{+}$)]. The dashed line is a $1^{+}$ state inferred from the level structure of ${}^8\mathrm{Li}$ based on mirror symmetry. The subset NCSM1 is the result of the most recent no-core shell model (NCSM) calculations with the CD-Bonn 2000 potential [16]. The subset GFMC1 is the earlier Green Function Monte Carlo (GFMC) result [17] with AV18/UIX Hamiltonians (values are for ${}^8\mathrm{Li}$, and excitation energies for the last two states, shown as green dashed-dotted lines, were calculated by using the variational Monte Carlo rather than theGFMC method). The subset GFMC2 is the more recent GFMC prediction [2] with AV18/IL2 Hamiltonians (values are for ${}^8\mathrm{Li}$). The subset NCSM2’ is the earlier NCSM result [3].Reuse & Permissions