Data of the Bertozzi experiment show close agreement with special relativity. Kinetic energy of five electron runs: 0.5, 1, 1.5, 4.5, 15 MeV (or 1, 2, 3, 9, 30 in mc²). Speed: 0.752, 0.828, 0.922, 0.974, 1.0 in c² (or 0.867, 0.910, 0.960, 0.987, 1 in c).
an experiment specifically aimed at demonstrating the relativistic effects in a very direct way was conducted by William Bertozzi (1962, 1964). He employed the electron accelerator facility at MIT in order to initiate five electron runs, with electrons of kinetic energies between 0.5 and 15 MeV. These electrons were produced by a Van de Graaff generator and traveled a distance of 8.4 m, until they hit an aluminium disc. First, the time of flight of the electrons was measured in all five runs – the velocity data obtained were in close agreement with the relativistic expectation. However, at this stage the kinetic energy was only indirectly determined by the accelerating fields. Therefore, the heat produced by some electrons hitting the aluminium disc was measured by calorimetry in order to directly obtain their kinetic energy - those results agreed with the expected energy within 10% error margin.