Fig. 4: Evolution of the H̅ accumulation rate, 2023 and 2024.

The red curve (circles) shows the non-Be⁺ assisted accumulation first prepared in 2023. The blue curve (squares) shows H̅ accumulation using the initially developed Be⁺ assisted procedure (July 2023). The green curve (triangles) shows the final Be⁺ assisted procedure after several loss-inducing steps had been removed in 2023. The orange curve (diamonds) shows accumulation in 2024 after additional improvements (see text) and a doubling of the p̅ number used for synthesis. Each dataset has been fit with a function that describes a constant rate of H̅ trapping per synthesis cycle and a fixed fractional loss of trapped H̅ per cycle (see text). The average time between individual cycles is four minutes. For the red, blue, green, and yellow curves, the fitted accumulation rates were 12 ± 1, 69 ± 1, 65 ± 1, and 163 ± 1 H̅ per cycle, respectively, and corresponding losses were 0.15 ± 0.12%, 2.7 ± 0.1%, 0.13 ± 0.01%, and 0.10 ± 0.03% of the trapped H̅ per cycle.