A Predictive Theory for Elastic Scattering and Recoil of Protons from   $^4$He
  Low-energy cross sections for elastic scattering and recoil of protons from $^4$He nuclei (also known as $\alpha$ particles) are calculated directly by solving the Schr\"odinger equation for five nucleons interacting through accurate two- and three-nucleon forces derived within the framework of chiral effective field theory. Precise knowledge of these processes at various proton backscattering/recoil angles and energies is needed for the ion-beam analysis of numerous materials, from the surface layers of solids, to thin films, to fusion-reactor materials. Indeed, the same elastic scattering process, in two different kinematic configurations, can be used to probe concentrations and depth profiles of either hydrogen or helium. We compare our results to available experimental data and show that direct calculations with modern nuclear potentials can help to resolve remaining inconsistencies among different data sets and can be used to predict these cross sections when measurements are not available. 
Guillaume Hupin, Sofia Quaglioni and Petr Navr\'atil
nucl-th