Fig. 1 Diagram of first experimental tube. S, radio-active source; W, thin glass window; F, filament; G, grid; R, lead to silvered surface; A, second anode; M, magnetic field; C, copper seals; Y, and Z, zinc sulfide screens.
"He produced a beam of alpha rays from polonium in a vacuum tube. He had a parabolic hot cathode electron emitter with a hole in the middle, and the alpha rays came through it and could be counted by scintillations on a zinc sulfide screen with a microscope over here (Y and Z). The electrons were focused on this plate, so that for a distance there was (p.1) a stream of electrons moving along with the alpha particles. Now you could accelerate the electrons and get them up to the velocity of the alpha particles. To get an electron to move with that velocity takes about 590 volts; so if you put 590 volts here, accelerating the electrons, the electrons would travel along with the alpha particles and the idea of the experiment was that if they moved along together at the same velocity they might recombine so that the alpha particle would lose one of its charges, would pick up an electron, so that instead of being a helium atom with two p! ositive charges it would only have one charge. Well, if an alpha particle with a double charge had one electron, itÂ’s like the Bohr theory of the hydrogen atom, and you know its energy levels. It's just like a hydrogen atom, with a Balmer series, and you can calculate the energy necessary to knock off this electron and so on. "
