Isotope Effect in Electron-Capture Differential Cross Sections at Intermediate Energies

The isotope dependence in the angular distribution of electron-capture cross sections for protons and deuterons with equal velocity ($E=40\mathrm{}$ keV/u) colliding with atomic hydrogen or deuterium targets is predicted theoretically and observed experimentally. A projectile-dependent effect is observed at small scattering angles. No target dependence was detected in the differential cross sections. A scaling relationship is determined which permits the prediction of differential cross sections for hydrogen-isotope projectiles.