The German original was published as Bethe, H. 1932. Bremsformel für Elektronen relativistischer Geschwindigkeit. Zeitschrift f. Phys. 76: 293–299.

The current translation is by Klaus Bartschat, Department of Physics and Astronomy, Drake University, Des Moines, Iowa 50311, USA; klaus.bartschat@drake.edu. An attempt has been made to preserve Bethe’s writing style as much as possible, including his use of “Volt” instead of “electron volt”. Even though the term “stopping power” is quite common in present scientific English, we generally use “braking [capability]” rather than “stopping [power]”, in order to emphasize the act [and ability] of slowing down the particle rather than the ultimate result of bringing it to a complete halt. Also, a few typographical errors were kept in the English translation to ensure the translation replicates the original paper. Please, see Section 3 of the annotation to Bethe’s article [Fontes, C.J., Bostock, C.J. and Bartschat, K. 2014. Eur. Phys. J. H, 39: 517-536] for a list. The references were converted to EPJH style, and the footnotes are numbered consecutively.

deceased: (2 December 1906 – 6 March 2005).

This paper was written while Hans Bethe was visiting the Institute of Physics of the Royal University of Rome, under invitation of Enrico Fermi.