Prediction of lithium isotope fluxes using data-driven production cross sections

TL;DR

This paper improves cosmic ray lithium flux predictions by updating production cross sections with new data, resolving previous discrepancies between models and measurements, and providing more accurate flux estimates.

Contribution

It introduces a data-driven renormalization of production cross sections to enhance cosmic ray lithium flux modeling accuracy.

Findings

Updated cross sections align predictions with AMS-02 measurements

Renormalization reduces overestimation of lithium spectra

Predicted spectra are consistent within uncertainties

Abstract

Galactic cosmic rays (CRs) generally share common propagation features, leading to consistent spectral observations of secondary nuclei such as Li, Be, and B. However, the Li spectrum predicted by the CR diffusion coefficient inferred from B/C is significantly lower than the latest measurement of AMS-02. This anomaly may be attributed to the missing contributions from the heavy nuclei components in cosmic rays. By including these missing contributions the excess of the Li spectrum disappears. However, another inconsistency still exists since the calculated Li spectrum is now overestimated compared to the data. In this work, we update the cross-section model used to calculate the Li production according to more cross-section measurements. We find that the cross sections of these added reactions are systematically overestimated, and should be renormalized to the interpolations of available data. As a result, our prediction of the total Li spectrum is consistent with the measurement without discrepancy, and our prediction of the $\rm^6Li$ and $\rm^7Li$ spectra are consistent with the preliminary measurements of AMS-02 within the cross-section uncertainties.