An expression for the Mott cross section of electrons and positrons on nuclei with Z up to 118

In the present work, an improved numerical solution for determining the ratio, RMott, of the unscreened Mott differential cross section (MDCS) with respect to Rutherford's formula is proposed for the scattering of electrons and positrons on nuclei with 1≤Z≤118. It accounts for incoming lepton energies between 1 keV and 900 MeV. For both electrons and positrons, a fitting formula and a set of fitting coefficients for the ratio RMott on nuclei are also presented. The found average error of the latter practical interpolated expression is typically lower than 1% also at low energy for electrons and lower than 0.05% for positrons for all nuclei over the entire energy range. Both the improved numerical solution and the interpolated practical expression were found in good agreement with the partially available previous calculations.