of beta particles with a wide range of energies. The earlier measurements by Kaufmann, Bucherer, and others had used flat parallel plate condensers which provided no focusing of the beta particles. Rogers et al. (Fig. 10) instead constructed an electrostatic spectrograph capable of resolving the energy maxima of individual beta particle lines from the radium decay series. The electrostatic spectrograph was constructed of segments of two cylinders and was enclosed in an evacuated iron box. The beta rays were emitted from a fine platinum wire coated with radium active-deposit. The dispersed rays were incident on a slit in front of a Geiger counter. The data from this experiment was combined with previous magnetic spectrometer measurements of Hρ to yield the charge-to-mass ratio, which was subsequently compared with the predictions of Lorentz and Abraham for the ratio of transverse mass and rest mass. The points were all on the curve representing the Lorentz–Einstein formula to within 1% (see Fig. 11). This experiment is seen as being sufficiently precise to distinguish between the theories. Modern tests Since then, many additional experiments concerning the relativistic energy–momentum relation have been conducted, including measurements of the deflection of electrons, all of them confirming special relativity to high precision. Also in modern particle accelerators, the predictions of special relativity are routinely confirmed. See also History of special relativity References Primary sources Secondary sources In English: External links Presentation on Kaufmann experiment (PowerPoint) List of SR tests Tests of special relativity