Impact of using the approximation ℱ = ℱ_HE for the calculation of (¹⁰Be/⁹Be)^TOA as a function of the kinetic energy per nucleon. Top panel: calculation from USINE (thin lines) and the analytical model (thick lines) for two different production cross-section sets (associated with different transport parameters and L values, as highlighted in the legend). Bottom panel: relative difference between the approximate calculation and the USINE calculation. The range highlighted in yellow corresponds to the region where the AMS-02 and HELIX experiments should measure ¹⁰Be/⁹Be.