A simple determination of the halo size from10Be/9Be data

Abstract

Context.The AMS-02 and HELIX experiments should soon provide10Be/9Be cosmic-ray data of unprecedented precision.Aims.We propose an analytical formula to quickly and accurately determineLfrom these data.Methods.Our formula is validated against the full calculation performed with the propagation codeUSINE. We compare the constraints onLset by Be/B and10Be/9Be, relying on updated sets of production cross-sections.Results.The best-fitLfrom AMS-02 Be/B data is shifted from 5 kpc to 3.8 kpc when using the updated cross-sections. We obtained consistent results from the Be/B analysis withUSINE,L = 3.8−1.6+2.8kpc (data and cross-section uncertainties), and from the analysis of10Be/9Be data with the simplified formula,L = 4.7 ± 0.6 (data uncertainties) ±2 (cross-section uncertainties) kpc. The analytical formula indicates that improvements onLthanks to future data will be limited by production cross-section uncertainties, unless either10Be/9Be measurements are extended up to several tens of GeV/n, or nuclear data for the production of10Be and9Be are improved; new data for the production cross section of16O into Be isotopes above a few GeV/n are especially desired.