Comptonionization of hydrogen atom near threshold by photons in the energy range of a few keV: nonrelativistic approachSalim Houamer, Ochbadrakh Chuluunbaatar, Igor P. Volobuev and Yuri V. PopovEur. Phys. J. D, 74 4 (2020) 81DOI: https://doi.org/10.1140/epjd/e2020-100572-1