In his book 'Deep Space' Colin A Ronan showed (136, Pan, 1983) that when an electron is accelerated in a cathode-ray tube it will be 'pulled downwards' by gravity but that this deviation can be overcome by the application of an electric charge via deflecting plates. This presumably complies with Kaufmann's circa 1901 cathode-ray experiments showing that the mass of an electron is subject to change and that the change depends on its velocity (161, 'Fiction Stranger Than Truth', 1981, Nikolai Rudakov). I understand that gamma factors in excess of 400,000 times a particle's (proton's?) rest mass have been generated by the LHC. My specific question is - how long does it take to accelerate a particle from rest to a velocity whereby its relativistic mass has increased to 400,000 times its rest mass?