Excitation of metastable helium atoms by positron impactLiam Wymer, Sharan Kumar, T. J. Gay, Sean S. Hodgman, Stephen J. Buckman and Joshua R. MachacekEur. Phys. J. D, 80 2 (2026) 12DOI: https://doi.org/10.1140/epjd/s10053-026-01123-0