Precise Electromagnetic Tests of Ab Initio Calculations of Light Nuclei: States in ¹⁰Be

In order to test ab initio calculations of light nuclei, we have remeasured lifetimes in ¹⁰Be using the Doppler shift attenuation method (DSAM) following the ⁷Li(⁷Li,α)¹⁰Be reaction at 8 and 10 MeV. The new experiments significantly reduce systematic uncertainties in the DSAM technique. The J^π=2₁⁺ state at 3.37 MeV has τ=205±(5)_stat±(7)_sys  fs corresponding to a B(E2↓) of 9.2(3)e²  fm⁴ in broad agreement with many calculations. The J^π=2₂⁺ state at 5.96 MeV was found to have a B(E2↓) of 0.11(2)e²  fm⁴ and provides a more discriminating test of nuclear models. New Green’s function Monte Carlo calculations for these states and transitions with a number of Hamiltonians are also reported and compared to experiment.