Light nuclei were created during big-bang nucleosynthesis (BBN). Standard BBN theory, using rates inferred from accelerator-beam data, cannot explain high levels of 6 Li in low-metallicity stars. Using highenergy-density plasmas we measure the Tð 3 He; γÞ 6 Li reaction rate, a candidate for anomalously high 6 Li production; we find that the rate is too low to explain the observations, and different than values used in common BBN models. This is the first data directly relevant to BBN, and also the first use of laboratory plasmas, at comparable conditions to astrophysical systems, to address a problem in nuclear astrophysics. DOI: 10.1103/PhysRevLett.117.035002 While most light nuclei abundances in primordial material are explained well by big-bang nucleosynthesis (BBN) theory [1][2][3], observations of high levels of 6 Li in low-metallicity stars [4,5] disagree with BBN models by 3 orders of magnitude. During BBN several nuclear reactions could produce excess 6 Li, in particular 4 HeðD; γÞ 6 Li and 3 HeðT; γÞ 6 Li. Recent work has ruled out the first reaction [6], while the latter has been hypothesized as a solution to this problem [7], if the rate is much higher than expected, or in nonstandard production models.The nuclear physics of the 3 HeðT; γÞ 6 Li reaction explaining these astrophysical observations is contentious [8] yet still an open question [3]. This is primarily due to the lack of high-quality data for this reaction, with previous experiments being conducted at high energies and with significant inconsistencies between the reported data sets [9]. Only one data set exists at low energy (E cm ≤ 1 MeV) [9], which is still higher than the range where BBN reactions occurred; the fidelity of this data has also been questioned in the literature [3,7]. This strongly motivates additional experiments to determine if this reaction could explain the observed levels of 6 Li in low-metallicity stars via BBN production.In this Letter we report on novel measurements of the Tð 3 He; γÞ 6 Li reaction using high-energy-density plasmas (HEDPs), which were generated by using the OMEGA laser facility [10], to implode gas-filled thin-glass "exploding pusher" [11] capsules. In these experiments, the laser delivered 17 kJ of energy in a 600 ps duration square pulse, illuminating the outer surface of a glass microballoon 960 μm in diameter and 2.5 μm thick, filled with T 2 and 3 He gas with a total pressure of 20 atm and a 30∶70 atomic mixture. Capsules filled with T 2 , 3 He, or a D 2 þ 3 He mixture were used for background measurements and instrument calibration. Ablation pressures on the order of tens of MBar rapidly developed as the laser energy was absorbed in the glass shell's outer surface, launching a strong spherically converging shock into the gas. When this shock reached the center of the capsule and rebounded, it created a high-temperature and high-density plasma in which nuclear reactions occurred [11]. In these implosions, ion temperatures reached ∼20 keV (2.3 × 10 8 K) while ion number densities were ∼4 × 1...
