First Measurement of the $B(E2;3/2^{-}\to 1/2^{-})$ Transition Strength in ${}^7$Be: Testing Ab Initio Predictions for $A=7$ Nuclei

Abstract

Electromagnetic observables are able to give insight into collective and emergent features in nuclei, including nuclear clustering. These observables also provide strong constraints for ab initio theory, but comparison of these observables between theory and experiment can be difficult due to the lack of convergence for relevant calculated values, such as $E2$ transition strengths. By comparing the ratios of $E2$ transition strengths for mirror transitions, we find that a wide range of ab initio calculations give robust and consistent predictions for this ratio. To experimentally test the validity of these ab initio predictions, we performed a Coulomb excitation experiment to measure the $B(E2;3/2^{-}\to 1/2^{-})$ transition strength in ${}^7$Be for the first time. A $B(E2;3/2^{-}\to 1/2^{-})$ value of $26(6)(3)e^2{\mathrm{fm}}^4$ was deduced from the measured Coulomb excitation cross section. This result is used with the experimentally known ${}^7$Li $B(E2;3/2^{-}\to 1/2^{-})$ value to provide an experimental ratio to compare with the ab initio predictions. Our experimental value is consistent with the theoretical ratios within $1\sigma$ uncertainty, giving experimental support for the value of these ratios. Further work in both theory and experiment can give insight into the robustness of these ratios and their physical meaning.

9 pages, 7 figures

References in corpus (5)

• Recent developments in no-core shell-model calculations
• Microscopic calculation of the 3He(alpha,gamma)7Be and 3H(alpha,gamma)7Li capture cross sections using realistic interactions
• Benchmark calculations for 3H, 4He, 16O and 40Ca with ab-initio coupled-cluster theory
• Quantum Monte Carlo calculations of electroweak transition matrix elements in A = 6,7 nuclei
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Cited by in corpus (8)

• Emergent Sp(3,R) dynamical symmetry in the nuclear many-body system from an ab initio description
• Ab initio study of the beryllium isotopes ${}^7$Be to ${}^{12}$Be
• Robust ab initio prediction of nuclear electric quadrupole observables by scaling to the charge radius
• Quadrupole moments and proton-neutron structure in p-shell mirror nuclei
• Ab initio estimation of $E2$ strengths in ${}^8$Li and its neighbors by normalization to the measured quadrupole moment
• Ab-initio no-core shell model study of ${}^{18-24}$Ne isotopes
• Robust ab initio predictions for dimensionless ratios of E2 and radius observables. I. Electric quadrupole moments and deformation
• Robust ab initio predictions for dimensionless ratios of E2 and radius observables. II. Estimation of E2 transition strengths by calibration to the charge radius