Media type: E-Article Title: Simple model for sequential multiphoton ionization by ultraintense x rays Contributor: Li, Xiang; Boll, Rebecca; Rolles, Daniel; Rudenko, Artem Published: American Physical Society (APS), 2021 Published in: Physical Review A, 104 (2021) 3 Language: English DOI: 10.1103/physreva.104.033115 ISSN: 2469-9926; 2469-9934 Origination: Footnote: